Tom, Kinda like rebuilding a carburetor on the kitchen table! LOL Bob W4JFA?
And I wonder how many of them, if married, are no longer
with us ??? hahahahaha
Tom Latimer
On 6/9/2024 06:08, Bill (Group Owner)
wrote:
There are some, who put entire chassis in the dishwasher as long
as things like transformers.
From our file department.
K2WH
|
Re: SX-117 noise limiter behavior
Rich ¨C Ignition noise is far from periodic. It may approach that at a constant speed, and may be somewhat predictable in the same vehicle where the receiver is. An SX117 for example and most others are used at home and are subject to numerous noise sources, the combination of which is anything but periodic. 73 ¨C Mike ? ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 908-902-3831 ?
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Show quoted text
From: [email protected] < [email protected]> On Behalf Of Richard Knoppow Sent: Sunday, June 9, 2024 9:16 PM To: [email protected]Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior ? Well, you are speaking of _random_ noise, like natural radio noise
but blankers are intended to work on periodic signals such as ignition
noise.
On 6/9/2024 5:11 PM, Mike Feher wrote: It seems to me, that since noise is neither correlate-able or
stochastic, elimination is not possible. Also the multiple antenna
theory is out the window since RF generated noise travels at the speed
of light. 73 ¨C Mike
Mike B. Feher, N4FS
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: SX-117 noise limiter behavior
True, but a good approximation of the noise in the vicinity of the receiver antenna can be sampled and used to reduce the noise coming in along with the desired signal from the main antenna.? The noise from the secondary system, must, as you point out, be as close as possible to the noise being picked up by the primary antenna.? Cancellation is, of course, incomplete, so elimination is not possible, but quite significant reduction is indeed possible and has been proven in the field.? Needless to say, the noise receiving system must not pick up much of the desired signal.? This can be effected both by operating the two receive systems on dissimilar frequencies, and also by utilizing a receive antenna location that will pick up the closest possible envelope to the noise the primary antenna receives but picks up a minimal amount of the desired signal.
How much improvement is available?? Results vary widely with the nature of the noise and the environment in which the noise is being received.? Still, the reduction is often very, very worthwhile!
As always, your mileage may vary!!
Mike/
K5MGR
_____________________________________________ ? Mike Langner
929 Alameda Road NW
Albuquerque, NM 87114-1901
(505) 898-3212 home/home office
(505) 238-8810 cell
mlangner@...
?
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Show quoted text
From: [email protected] < [email protected]> On Behalf Of Mike Feher Sent: Sunday, June 9, 2024 6:11 PM To: [email protected]Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior ? It seems to me, that since noise is neither correlate-able or stochastic, elimination is not possible. Also the multiple antenna theory is out the window since RF generated noise travels at the speed of light. 73 ¨C Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 908-902-3831 ? ? Another technique for reducing or eliminating noise was to introduce
local noise to the front end of a receiver from a local "noise antenna."
The amplitude and phase of that noise could be adjusted to, hopefully,
cancel the noise received by the signal antenna.
Early BC-342 and BC-312 receivers featured a noise suppression circuit
of this type. War Department TM 11-850 states that the noise antenna
was intended to eliminate ignition noise when the receiver was mounted
in a vehicle.
By the time my BC-342-N was born (1942), the noise antenna and
associated circuitry were omitted, so that circuit may not have worked
well. The September, 1946 revision of the TM notes that spare parts
were no longer available for the noise suppression circuit and
recommends removing it if any of the components fail.
MFJ has featured at least one similar unit, the MFJ-1026, which is now
listed as sold out. There are other such units available but I have no
experience with them.
73,
Maynard
W6PAP
|
Re: SX-117 noise limiter behavior
Well, you are speaking of _random_ noise, like natural radio noise
but blankers are intended to work on periodic signals such as ignition
noise.
toggle quoted message
Show quoted text
On 6/9/2024 5:11 PM, Mike Feher wrote: It seems to me, that since noise is neither correlate-able or
stochastic, elimination is not possible. Also the multiple antenna
theory is out the window since RF generated noise travels at the speed
of light. 73 ¨C Mike
Mike B. Feher, N4FS
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: SX-117 noise limiter behavior
I believe the Collins used this technique for the NB on the 75S and
51S receivers. Should really look. It has the advantage of a very wide
band input. For ignition and other pulse noise the NB listened on some
VHF frequency.
toggle quoted message
Show quoted text
On 6/9/2024 4:30 PM, Maynard Wright, P. E., W6PAP via groups.io wrote: Another technique for reducing or eliminating noise was to introduce
local noise to the front end of a receiver from a local "noise antenna."
The amplitude and phase of that noise could be adjusted to, hopefully,
cancel the noise received by the signal antenna.
Early BC-342 and BC-312 receivers featured a noise suppression circuit
of this type. War Department TM 11-850 states that the noise antenna
was intended to eliminate ignition noise when the receiver was mounted
in a vehicle.
By the time my BC-342-N was born (1942), the noise antenna and
associated circuitry were omitted, so that circuit may not have worked
well. The September, 1946 revision of the TM notes that spare parts
were no longer available for the noise suppression circuit and
recommends removing it if any of the components fail.
MFJ has featured at least one similar unit, the MFJ-1026, which is now
listed as sold out. There are other such units available but I have no
experience with them.
73,
Maynard
W6PAP
|
And I wonder how many of them, if married, are no longer
with us ??? hahahahaha
Tom Latimer
On 6/9/2024 06:08, Bill (Group Owner)
wrote:
toggle quoted message
Show quoted text
There are some, who put entire chassis in the dishwasher as long
as things like transformers.
From our file department.
K2WH
|
Re: SX-117 noise limiter behavior
It seems to me, that since noise is neither correlate-able or stochastic, elimination is not possible. Also the multiple antenna theory is out the window since RF generated noise travels at the speed of light. 73 ¨C Mike ? Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 908-902-3831 ?
toggle quoted message
Show quoted text
From: [email protected] < [email protected]> On Behalf Of Maynard Wright, P. E., W6PAP via groups.io Sent: Sunday, June 9, 2024 7:31 PM To: [email protected]Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior ? Another technique for reducing or eliminating noise was to introduce
local noise to the front end of a receiver from a local "noise antenna."
The amplitude and phase of that noise could be adjusted to, hopefully,
cancel the noise received by the signal antenna.
Early BC-342 and BC-312 receivers featured a noise suppression circuit
of this type. War Department TM 11-850 states that the noise antenna
was intended to eliminate ignition noise when the receiver was mounted
in a vehicle.
By the time my BC-342-N was born (1942), the noise antenna and
associated circuitry were omitted, so that circuit may not have worked
well. The September, 1946 revision of the TM notes that spare parts
were no longer available for the noise suppression circuit and
recommends removing it if any of the components fail.
MFJ has featured at least one similar unit, the MFJ-1026, which is now
listed as sold out. There are other such units available but I have no
experience with them.
73,
Maynard
W6PAP
|
Re: SX-117 noise limiter behavior
Another technique for reducing or eliminating noise was to introduce
local noise to the front end of a receiver from a local "noise antenna."
The amplitude and phase of that noise could be adjusted to, hopefully,
cancel the noise received by the signal antenna.
Early BC-342 and BC-312 receivers featured a noise suppression circuit
of this type. War Department TM 11-850 states that the noise antenna
was intended to eliminate ignition noise when the receiver was mounted
in a vehicle.
By the time my BC-342-N was born (1942), the noise antenna and
associated circuitry were omitted, so that circuit may not have worked
well. The September, 1946 revision of the TM notes that spare parts
were no longer available for the noise suppression circuit and
recommends removing it if any of the components fail.
MFJ has featured at least one similar unit, the MFJ-1026, which is now
listed as sold out. There are other such units available but I have no
experience with them.
73,
Maynard
W6PAP
toggle quoted message
Show quoted text
On 6/8/24 20:22, Richard Knoppow wrote: Can't read the whole book:-) Look at any of the classical receivers,
say a Hallicrafters S-40. That has a series diode noise limiter. I think
the S-20R has a shunt limiter. Series limiters began to appear in the
early 1940s. They were "automatic" in that the clipping level depended
on the carrier strength. For AM signals the carrier would set the
limiter for about 100% modulation, keeping the distortion fairly low
(still had distortion). When there was no carrier, in between stations,
the clipping was lower. When used with a BFO the BFO was the carrier and
might prevent effective noise reduction. Receivers with shunt limiters
often had a front panel adjustment. It could be set to minimize
distortion on AM and to provide fairly deep clipping for CW where audio
distortion was not critical.
There were many variations of noise limiters, for instance see the
schematic for the Hammarlund SP-200 Super-Pro which uses a triode
limiter and the patented limiter in the RCA AR-88. The AR-88 limiter is
pretty effective.
Most limiters work at audio. They limit or clip off the peaks of the
detected audio. This has no effect on noise that gets into the AVC. The
AVC tends to integrate the noise pulses which affect it just as a
carrier would and tend to desensitize the receiver.
A noise blanker, following the idea of J.J.Lamb, works at the IF
frequency. The wider the band where its applied the better. The blanker
sees pulses, like impulse noise from ignition, which are above a pre-set
threshold, and produces DC pulses from them which are applied to a gate
circuit which cuts off the IF channel during the noise. This prevents
the pulses from getting to the AVC detector so they have no effect on
the sensitivity of the receiver. At least that is how its supposed to
work. But, the bandwidth where the pulses are detected must be wide
enough so it does not stretch out the pulses or cause them to be
smeared. If too narrow the muting signal will be too broad and reduced
in amplitude so the muting will become obvious and reduced in
effectiveness. In addition, the bandwidth of the circuit where the
muting pulses are applied must also be wide enough to the "holes"
punched in the signal are not stretched out. Modern noise blankers do
this fairly well but the first attempt at a practical embodiment, namely
the NB in the SX-28, did not work very well. Probably neither Lamb or
the Hallicrafters engineers fully understood the requirements. In fact,
there is a service letter for the SX-28 from Hallicrafters showing how
to competely disable and remove the Lamb noise blanker and replace it
with a conventional series noise limiter.
The arrangement in the SX-117 is not a noise blanker since it
doesn't poke holes in the IF signal. Rather it is a peak limiter working
in the IF rather than for detected audio. It is able to limit the peaks
of the IF signal which is similar to the effect of the noise blanker in
that it prevents large noise pulses from being integrated by the AVC
detector and causing the AVC signal to desensitize the receiver. Of
course it also affects the audio, reducing the audibility of the noise.
However, since it is not seeing detected carrier as it would following
the detector, its clipping level is not controlled by the signal
strength and it can clip modulation peaks unless some method is
available to reduce the input signal to the limiter to a low level where
the modulation peaks are not too much affected. It will have the virtue
of working well for CW and SSB where no carrier appears in the IF. The
effective carrier is the BFO, which is injected at the detector (either
diode or product) at a point after the clipping circuit. Since the
carrier for AM is part of the signal at IF it does affect the level at
the clipping diodes and can be distorted. The instruction book suggests
reducing the RF gain. That reduces the level everywhere the AVC or
manual gain works, including the level at the clipping diodes.
So, since probably the receiver will be used more often for CW and
SSB than for AM this system works quite weil and is much simpler than a
true noise blanker. Perhaps there should also have been a conventional
audio limiter available for AM but it would have cost something to have
it and the necessary switching.
Hallicrafters had a lot of innovative circuits over they years,
some worked well, some, like the Lamb blanker, were not embodied well
and didn't work so well. BTW, Lamb also invented the single crystal IF
filter. I think National was the first to employ it but Hallicrafters
was not far behind. It became universal in better quality receivers.
FWIW the best of the crystal filter circuits is the one patented by
Hammarlund and first used in the HQ-120-X.
I am writing too much. I hope this is of some interest.
On 6/8/2024 7:16 PM, don Root wrote:
Back to noise? stuff only
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
There are some, who put entire chassis in the dishwasher as long as components like transformers and/or coils are removed.
From our file department.
K2WH
|
Re: SX-117 noise limiter behavior
Can't read the whole book:-) Look at any of the classical receivers,
say a Hallicrafters S-40. That has a series diode noise limiter. I think
the S-20R has a shunt limiter. Series limiters began to appear in the
early 1940s. They were "automatic" in that the clipping level depended
on the carrier strength. For AM signals the carrier would set the
limiter for about 100% modulation, keeping the distortion fairly low
(still had distortion). When there was no carrier, in between stations,
the clipping was lower. When used with a BFO the BFO was the carrier and
might prevent effective noise reduction. Receivers with shunt limiters
often had a front panel adjustment. It could be set to minimize
distortion on AM and to provide fairly deep clipping for CW where audio
distortion was not critical.
There were many variations of noise limiters, for instance see the
schematic for the Hammarlund SP-200 Super-Pro which uses a triode
limiter and the patented limiter in the RCA AR-88. The AR-88 limiter is
pretty effective.
Most limiters work at audio. They limit or clip off the peaks of the
detected audio. This has no effect on noise that gets into the AVC. The
AVC tends to integrate the noise pulses which affect it just as a
carrier would and tend to desensitize the receiver.
A noise blanker, following the idea of J.J.Lamb, works at the IF
frequency. The wider the band where its applied the better. The blanker
sees pulses, like impulse noise from ignition, which are above a pre-set
threshold, and produces DC pulses from them which are applied to a gate
circuit which cuts off the IF channel during the noise. This prevents
the pulses from getting to the AVC detector so they have no effect on
the sensitivity of the receiver. At least that is how its supposed to
work. But, the bandwidth where the pulses are detected must be wide
enough so it does not stretch out the pulses or cause them to be
smeared. If too narrow the muting signal will be too broad and reduced
in amplitude so the muting will become obvious and reduced in
effectiveness. In addition, the bandwidth of the circuit where the
muting pulses are applied must also be wide enough to the "holes"
punched in the signal are not stretched out. Modern noise blankers do
this fairly well but the first attempt at a practical embodiment, namely
the NB in the SX-28, did not work very well. Probably neither Lamb or
the Hallicrafters engineers fully understood the requirements. In fact,
there is a service letter for the SX-28 from Hallicrafters showing how
to competely disable and remove the Lamb noise blanker and replace it
with a conventional series noise limiter.
The arrangement in the SX-117 is not a noise blanker since it
doesn't poke holes in the IF signal. Rather it is a peak limiter working
in the IF rather than for detected audio. It is able to limit the peaks
of the IF signal which is similar to the effect of the noise blanker in
that it prevents large noise pulses from being integrated by the AVC
detector and causing the AVC signal to desensitize the receiver. Of
course it also affects the audio, reducing the audibility of the noise.
However, since it is not seeing detected carrier as it would following
the detector, its clipping level is not controlled by the signal
strength and it can clip modulation peaks unless some method is
available to reduce the input signal to the limiter to a low level where
the modulation peaks are not too much affected. It will have the virtue
of working well for CW and SSB where no carrier appears in the IF. The
effective carrier is the BFO, which is injected at the detector (either
diode or product) at a point after the clipping circuit. Since the
carrier for AM is part of the signal at IF it does affect the level at
the clipping diodes and can be distorted. The instruction book suggests
reducing the RF gain. That reduces the level everywhere the AVC or
manual gain works, including the level at the clipping diodes.
So, since probably the receiver will be used more often for CW and
SSB than for AM this system works quite weil and is much simpler than a
true noise blanker. Perhaps there should also have been a conventional
audio limiter available for AM but it would have cost something to have
it and the necessary switching.
Hallicrafters had a lot of innovative circuits over they years,
some worked well, some, like the Lamb blanker, were not embodied well
and didn't work so well. BTW, Lamb also invented the single crystal IF
filter. I think National was the first to employ it but Hallicrafters
was not far behind. It became universal in better quality receivers.
FWIW the best of the crystal filter circuits is the one patented by
Hammarlund and first used in the HQ-120-X.
I am writing too much. I hope this is of some interest.
toggle quoted message
Show quoted text
On 6/8/2024 7:16 PM, don Root wrote: Back to noise? stuff only
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: SX-117 noise limiter behavior
Back to noise? stuff only
Richard you say halli used a ?Noise ?LIMMITER ?, not a blanker? but it is an ¡°unusual noise limiter arrangement¡±
Is there a standard arrangement? And what is it? ???Oh --maybe there is an old book on the topic.. or an ARRL handbook
?
?
see? page pdf? 105?? ----- ? added 9 june??? due to Richard's comment?
can see?? Limiters for halli , national , heath,? hammarlund???? but??? No blankers! ?????
will look for others later.. for a little education¡»å´Ç²Ô
?
From: [email protected] [mailto:[email protected]] On Behalf Of Richard Knoppow
Sent: Saturday, June 8, 2024 4:36 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior
?
Well, that's useful to know. Actually, I have some Kroil, my local
hardware store just began to stock it along with gun cleaning stuff.
I agree that recommendations for cleaning based on experience would
be valuable to the list. I also use Barkeepers Friend and also Zud which
appears to be identical. I also use plain toothpaste for cleaning
delicate items and polishing plastic. It works as well as the expensive
special plastic polishing cleaners.
This problem is interesting because Hallicrafters used an unusual
noise limiter arrangement. It would be interesting to know what other
receivers use it. Namely, a diode clipping limiter in the IF rather than
detected audio. In the SX-117 it serves to keep the noise peaks from
activating the AVC, which is the purpose of the Lamb type noise blanker,
but is much simpler. However, it does not have the advantage of the
"automatic" series noise limiter found in older receivers of minimizing
distortion on AM. It should work better for CW or SSB where the BFO in
the usual set up makes the noise limiter inactive.
Hallicrafters was the first to use the Lamb type blanker (in the
SX-28) but it did not work well there and I suspect they did not quite
understand how it works.
On 6/8/2024 8:00 AM, Jim Whartenby via groups.io wrote:
Richard
I am recommending penetrating oil to clean and lube switches and pots.
Kroil, Deoxit and the like are effective but are also expensive.? Just
trying to point out that there are alternatives to name brand items
which also do a decent job at a very reasonable price.
Perhaps we should share some cleaning tips on the reflector.? I am sure
that there are many products that do a decent job and are less
expensive.? I can recommend Bar Keeper's Friend for general metal
cleaning, it works well for me.? For wood cabinets, waterless hand
cleaner also does a decent job without harming the remining finish.
Regards,
Jim
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998 ?
-- don??? va3drl
|
I didn't believe it, till I used it, but for cleaning radios... chassis
and all - "Scrubbing Bubbles"? works swell.
TriFlo teflon lube is good for breaking loose Pot and Variable Cap
shafts... a tiny bit, and it'll work it's way into the "jam"... keep
workingj it, and when it DOES break loose, it's already lubed.
Tom - W?EAJ
|
Re: SX-117 noise limiter behavior
Well, that's useful to know. Actually, I have some Kroil, my local
hardware store just began to stock it along with gun cleaning stuff.
I agree that recommendations for cleaning based on experience would
be valuable to the list. I also use Barkeepers Friend and also Zud which
appears to be identical. I also use plain toothpaste for cleaning
delicate items and polishing plastic. It works as well as the expensive
special plastic polishing cleaners.
This problem is interesting because Hallicrafters used an unusual
noise limiter arrangement. It would be interesting to know what other
receivers use it. Namely, a diode clipping limiter in the IF rather than
detected audio. In the SX-117 it serves to keep the noise peaks from
activating the AVC, which is the purpose of the Lamb type noise blanker,
but is much simpler. However, it does not have the advantage of the
"automatic" series noise limiter found in older receivers of minimizing
distortion on AM. It should work better for CW or SSB where the BFO in
the usual set up makes the noise limiter inactive.
Hallicrafters was the first to use the Lamb type blanker (in the
SX-28) but it did not work well there and I suspect they did not quite
understand how it works.
toggle quoted message
Show quoted text
On 6/8/2024 8:00 AM, Jim Whartenby via groups.io wrote: Richard
I am recommending penetrating oil to clean and lube switches and pots.
Kroil, Deoxit and the like are effective but are also expensive.? Just
trying to point out that there are alternatives to name brand items
which also do a decent job at a very reasonable price.
Perhaps we should share some cleaning tips on the reflector.? I am sure
that there are many products that do a decent job and are less
expensive.? I can recommend Bar Keeper's Friend for general metal
cleaning, it works well for me.? For wood cabinets, waterless hand
cleaner also does a decent job without harming the remining finish.
Regards,
Jim
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Anyone have an SX series S meter they wish to part with? SX99 I am working with needs one replaced. Plastic face is broken and cracked badly.?
thanks
keith?
|
Re: SX-117 noise limiter behavior
Richard I am recommending penetrating oil to clean and lube switches and pots.? Kroil, Deoxit and the like are effective but are also expensive.? Just trying to point out that there are alternatives to name brand items which also do a decent job at a very reasonable price.
Perhaps we should share some cleaning tips on the reflector.? I am sure that there are many products that do a decent job and are less expensive.? I can recommend Bar Keeper's Friend for general metal cleaning, it works well for me.? For wood cabinets, waterless hand cleaner also does a decent job without harming the remining finish. Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
The noise limiter in the SX117 is somewhat unusual. It is a diode
noise clipper, similar to the conventional limiters found in many
receivers, but works at IF frequency rather than audio. It is NOT a
noise blanker. The comments in the instructions are very similar to
those for a conventional limiter. In CW it works because there is no BFO
present at the point of clipping or limiting. The same for SSB. The
distortion on AM really traces to the same cause. In a conventional
series limiter the detected carrier sets the clipping point. In most
receivers its set at about the 100% modulation level but usually
produces some clipping below that. In conventional receivers the clipper
will be biased by the BFO. Since for CW or SSB the BFO level is usually
higher than the signal the clipping level is usually well above the
signal so the effectiveness of the limiter is, well, limited. Some
receivers use a shunt arrangement where there is a manual limiting
control. This can be set to produce more noise reduction on CW or SSB
but must be set for AM signals to minimize distortion.
Since the limiter is in the 50Khz IF, before the AVC it has somewhat
the advantage of a noise blanker of minimizing desensitizing by
preventing noise from influencing the AVC.
Why it isn't working? Guesswork, something is causing the diodes to
short the IF signal. Bad diode perhaps, there is really not much there.
Its hard to find on the schematic.
I generally use Deoxit for switches and Fader lube for pots, have
had long term good results. I have never tried Kroil for either and am
not certain Jim is recommending it.
On 6/8/2024 12:42 AM, Jim Whartenby via groups.io wrote: Floyd
You originally said: "Haven't dug into this yet, but wonder what other
SX-117 users see when turning on the Noise Limiter in? USB or LSB mode.
On my receiver, it's like disconnecting the antenna - an S9+20 signal
falls to S1."
If you had only read the SX-117 manual first you could have answered
your own question, see page 11, bottom of the second column.? Cutting to
the chase, the noise limiter is most useful in CW, somewhat useful in
SSB and causes distortion in AM.? Backing off of the RF gain control
will reduce some distortion.
You mentioned that the SX-117 had been repaired in the past.? If that
included replacing the HD6225 diodes then I would check to see if they
are now Germanium.? The HD6225 is a silicon diode from the dim past of
silicon diode availability.? I have not found a datasheet for it but I
would suggest using a high conductance, low reverse leakage, diode.? One
sub would be the FD333 which has 1/10 the leakage current of the
1N4148.? I am sure that there are others.? But the 1N4148 or the 1N914
would most likely be just as good.
As for the use of a spray to clean and lubricate switches and pots, I
found the info below at the Kroil site:
<>
*"What to Expect from a Penetrating Oil*
There are several benefits to choosing penetrating oil over other
products on the market. It offers lubrication, noise reduction, cleaning
power, and is corrosion resistant. Each brand will be slightly
different, but we want to share what to expect from most of the
traditional penetrating oils available today.
* *Penetration*?¨C Penetrating oils penetrate rust and corrosion in
threads, spaces, and small openings of frozen or seized metal parts
that might seem impossible to reach. Penetrating oil can work
quickly to help loosen items that you thought were a lost cause.
* *Reduction of Noise*?¨C If you¡¯re dealing with industrial equipment,
or a deafening suspension, penetrating oils are made to help. The
way the oil is created helps cut down on both friction and rust,
which is often responsible for creating these noises.
* *Lubrication*?¨C Penetrating oil contains lubricant, although the
actual amount depends on the brand and ingredient list. Sometimes
the lubrication is temporary, but it can also last for a long time
with the right components in the mix. The product can be used to
lubricate mechanical parts on various items. In addition, it helps
with loosening stuck parts, removing tight nuts and bolts, and
reducing friction.
* *Resistance to Corrosion*?¨C Penetrating oils are made to protect any
kind of metal surface from the issues related to corrosion. This is
huge since corrosion is a common enemy of metal used in the
construction of mechanical components. The formulation of the
penetrant works to displace moisture, which helps fight against rust
and other situations that create corrosion.
* *Cleaning Power*?¨C It¡¯s essential to look at the product information
to be sure, but many types of penetrating oil are made to be used
for cleaning. They are especially useful for removing grease,
adhesive, tar, and rust. The oil acts as a solvent which means that
the items it is placed on will start to soften. This makes it much
easier to remove what is left with a soft cloth or a wipe of some sort."
My go to spray is Dollar Store penetrating oil.? It is cheap and works
very well on switches and pots.? I have had no problems at all for the
last dozen years using this product.? Just as good as anything costing
10 times or more the new going price of $1.50 per can.? Like everything
else in life, moderation is key.
If your go to spray is WD-40 then I would agree that if one used
nothing, that would be far better then using
WD-40.? This junk turns to gum over a short period of time and makes
matters much worse for switches, pots and gears.
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.
Murphy
On Friday, June 7, 2024 at 04:56:42 PM CDT, don Root
<drootofallevil@...> wrote:
So, guys, where is the formal non-partisan definition of..
"noise blanker"
"noise limiter"
Is there a defined difference between them ? and do the terms define? an
intent or a specific circuit?
Sorry to interfere but my poor education did not address this; at least
not that I remember.¡»å´Ç²Ô
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Floyd - K8AC
*Sent:* Friday, June 7, 2024 5:06 PM
*To:* [email protected]
*Subject:* Re: [HallicraftersRadios] SX-117 noise limiter behavior
I had hoped that someone who has actually seen and used an SX-117 would
respond.? I've only been restoring receivers for 40 years or so, but
over that time I've learned that you can save a lot of time by
consulting with someone else who owns the same radio when observing an
odd behavior.? You might be surprised how many times "they all do that"
is the undesirable but true answer.? As I said, I have not dug into this
particular problem yet.? What I do know is that the SX-117 does not have
a "noise blanker" as seen in later or more sophisticated receivers like
the Drake R4C.? It is described as a noise limiter.? This particular
SX-117 has been completely restored with all new tubes and many
capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All
switches in this unit have been carefully cleaned using De-Oxit and Q
tips and tooth picks to apply the cleaner in small amounts where needed. ,_
--
don??? va3drl
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: SX-117 noise limiter behavior
The noise limiter in the SX117 is somewhat unusual. It is a diode
noise clipper, similar to the conventional limiters found in many
receivers, but works at IF frequency rather than audio. It is NOT a
noise blanker. The comments in the instructions are very similar to
those for a conventional limiter. In CW it works because there is no BFO
present at the point of clipping or limiting. The same for SSB. The
distortion on AM really traces to the same cause. In a conventional
series limiter the detected carrier sets the clipping point. In most
receivers its set at about the 100% modulation level but usually
produces some clipping below that. In conventional receivers the clipper
will be biased by the BFO. Since for CW or SSB the BFO level is usually
higher than the signal the clipping level is usually well above the
signal so the effectiveness of the limiter is, well, limited. Some
receivers use a shunt arrangement where there is a manual limiting
control. This can be set to produce more noise reduction on CW or SSB
but must be set for AM signals to minimize distortion.
Since the limiter is in the 50Khz IF, before the AVC it has somewhat
the advantage of a noise blanker of minimizing desensitizing by
preventing noise from influencing the AVC.
Why it isn't working? Guesswork, something is causing the diodes to
short the IF signal. Bad diode perhaps, there is really not much there.
Its hard to find on the schematic.
I generally use Deoxit for switches and Fader lube for pots, have
had long term good results. I have never tried Kroil for either and am
not certain Jim is recommending it.
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On 6/8/2024 12:42 AM, Jim Whartenby via groups.io wrote: Floyd
You originally said: "Haven't dug into this yet, but wonder what other
SX-117 users see when turning on the Noise Limiter in? USB or LSB mode.
On my receiver, it's like disconnecting the antenna - an S9+20 signal
falls to S1."
If you had only read the SX-117 manual first you could have answered
your own question, see page 11, bottom of the second column.? Cutting to
the chase, the noise limiter is most useful in CW, somewhat useful in
SSB and causes distortion in AM.? Backing off of the RF gain control
will reduce some distortion.
You mentioned that the SX-117 had been repaired in the past.? If that
included replacing the HD6225 diodes then I would check to see if they
are now Germanium.? The HD6225 is a silicon diode from the dim past of
silicon diode availability.? I have not found a datasheet for it but I
would suggest using a high conductance, low reverse leakage, diode.? One
sub would be the FD333 which has 1/10 the leakage current of the
1N4148.? I am sure that there are others.? But the 1N4148 or the 1N914
would most likely be just as good.
As for the use of a spray to clean and lubricate switches and pots, I
found the info below at the Kroil site:
<>
*"What to Expect from a Penetrating Oil*
There are several benefits to choosing penetrating oil over other
products on the market. It offers lubrication, noise reduction, cleaning
power, and is corrosion resistant. Each brand will be slightly
different, but we want to share what to expect from most of the
traditional penetrating oils available today.
* *Penetration*?¨C Penetrating oils penetrate rust and corrosion in
threads, spaces, and small openings of frozen or seized metal parts
that might seem impossible to reach. Penetrating oil can work
quickly to help loosen items that you thought were a lost cause.
* *Reduction of Noise*?¨C If you¡¯re dealing with industrial equipment,
or a deafening suspension, penetrating oils are made to help. The
way the oil is created helps cut down on both friction and rust,
which is often responsible for creating these noises.
* *Lubrication*?¨C Penetrating oil contains lubricant, although the
actual amount depends on the brand and ingredient list. Sometimes
the lubrication is temporary, but it can also last for a long time
with the right components in the mix. The product can be used to
lubricate mechanical parts on various items. In addition, it helps
with loosening stuck parts, removing tight nuts and bolts, and
reducing friction.
* *Resistance to Corrosion*?¨C Penetrating oils are made to protect any
kind of metal surface from the issues related to corrosion. This is
huge since corrosion is a common enemy of metal used in the
construction of mechanical components. The formulation of the
penetrant works to displace moisture, which helps fight against rust
and other situations that create corrosion.
* *Cleaning Power*?¨C It¡¯s essential to look at the product information
to be sure, but many types of penetrating oil are made to be used
for cleaning. They are especially useful for removing grease,
adhesive, tar, and rust. The oil acts as a solvent which means that
the items it is placed on will start to soften. This makes it much
easier to remove what is left with a soft cloth or a wipe of some sort."
My go to spray is Dollar Store penetrating oil.? It is cheap and works
very well on switches and pots.? I have had no problems at all for the
last dozen years using this product.? Just as good as anything costing
10 times or more the new going price of $1.50 per can.? Like everything
else in life, moderation is key.
If your go to spray is WD-40 then I would agree that if one used
nothing, that would be far better then using
WD-40.? This junk turns to gum over a short period of time and makes
matters much worse for switches, pots and gears.
Regards,
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.
Murphy
On Friday, June 7, 2024 at 04:56:42 PM CDT, don Root
<drootofallevil@...> wrote:
So, guys, where is the formal non-partisan definition of..
"noise blanker"
"noise limiter"
Is there a defined difference between them ? and do the terms define? an
intent or a specific circuit?
Sorry to interfere but my poor education did not address this; at least
not that I remember.¡»å´Ç²Ô
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Floyd - K8AC
*Sent:* Friday, June 7, 2024 5:06 PM
*To:* [email protected]
*Subject:* Re: [HallicraftersRadios] SX-117 noise limiter behavior
I had hoped that someone who has actually seen and used an SX-117 would
respond.? I've only been restoring receivers for 40 years or so, but
over that time I've learned that you can save a lot of time by
consulting with someone else who owns the same radio when observing an
odd behavior.? You might be surprised how many times "they all do that"
is the undesirable but true answer.? As I said, I have not dug into this
particular problem yet.? What I do know is that the SX-117 does not have
a "noise blanker" as seen in later or more sophisticated receivers like
the Drake R4C.? It is described as a noise limiter.? This particular
SX-117 has been completely restored with all new tubes and many
capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All
switches in this unit have been carefully cleaned using De-Oxit and Q
tips and tooth picks to apply the cleaner in small amounts where needed. ,_
--
don??? va3drl
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: SX-117 noise limiter behavior
Floyd You originally said: "Haven't dug into this yet, but wonder what other SX-117 users see when turning on the Noise Limiter in? USB or LSB mode.? On my receiver, it's like disconnecting the antenna - an S9+20 signal falls to S1."
If you had only read the SX-117 manual first you could have answered your own question, see page 11, bottom of the second column.? Cutting to the chase, the noise limiter is most useful in CW, somewhat useful in SSB and causes distortion in AM.? Backing off of the RF gain control will reduce some distortion.
You mentioned that the SX-117 had been repaired in the past.? If that included replacing the HD6225 diodes then I would check to see if they are now Germanium.? The HD6225 is a silicon diode from the dim past of silicon diode availability.? I have not found a datasheet for it but I would suggest using a high conductance, low reverse leakage, diode.? One sub would be the FD333 which has 1/10 the leakage current of the 1N4148.? I am sure that there are others.? But the 1N4148 or the 1N914 would most likely be just as good.
As for the use of a spray to clean and lubricate switches and pots, I found the info below?at the Kroil site:?
"What to Expect from a Penetrating Oil
There are several benefits to choosing penetrating oil over other products on the market. It offers lubrication, noise reduction, cleaning power, and is corrosion resistant. Each brand will be slightly different, but we want to share what to expect from most of the traditional penetrating oils available today. - Penetration?¨C Penetrating oils penetrate rust and corrosion in threads, spaces, and small openings of frozen or seized metal parts that might seem impossible to reach. Penetrating oil can work quickly to help loosen items that you thought were a lost cause.
- Reduction of Noise?¨C If you¡¯re dealing with industrial equipment, or a deafening suspension, penetrating oils are made to help. The way the oil is created helps cut down on both friction and rust, which is often responsible for creating these noises.
- Lubrication?¨C Penetrating oil contains lubricant, although the actual amount depends on the brand and ingredient list. Sometimes the lubrication is temporary, but it can also last for a long time with the right components in the mix. The product can be used to lubricate mechanical parts on various items. In addition, it helps with loosening stuck parts, removing tight nuts and bolts, and reducing friction.
- Resistance to Corrosion?¨C Penetrating oils are made to protect any kind of metal surface from the issues related to corrosion. This is huge since corrosion is a common enemy of metal used in the construction of mechanical components. The formulation of the penetrant works to displace moisture, which helps fight against rust and other situations that create corrosion.
- Cleaning Power?¨C It¡¯s essential to look at the product information to be sure, but many types of penetrating oil are made to be used for cleaning. They are especially useful for removing grease, adhesive, tar, and rust. The oil acts as a solvent which means that the items it is placed on will start to soften. This makes it much easier to remove what is left with a soft cloth or a wipe of some sort."
My go to spray is Dollar Store penetrating oil.? It is cheap and works very well on switches and pots.? I have had no problems at all for the last dozen years using this product.? Just as good as anything costing 10 times or more the new going price of $1.50 per can.? Like everything else in life, moderation is key.
If your go to spray is WD-40 then I would agree that if one used nothing, that would be far better then using? WD-40.? This junk turns to gum over a short period of time and makes matters much worse for switches, pots and gears. Regards, Jim Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy
So, guys, where is the formal non-partisan definition of.. "noise blanker" "noise limiter" Is there a defined difference between them ? and do the terms define? an intent or a specific circuit? Sorry to interfere but my poor education did not address this; at least not that I remember. ¡»å´Ç²Ô
From: [email protected] [mailto:[email protected]] On Behalf Of Floyd - K8AC
Sent: Friday, June 7, 2024 5:06 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior ? I had hoped that someone who has actually seen and used an SX-117 would respond.? I've only been restoring receivers for 40 years or so, but over that time I've learned that you can save a lot of time by consulting with someone else who owns the same radio when observing an odd behavior.? You might be surprised how many times "they all do that" is the undesirable but true answer.? As I said, I have not dug into this particular problem yet.? What I do know is that the SX-117 does not have a "noise blanker" as seen in later or more sophisticated receivers like the Drake R4C.? It is described as a noise limiter.? This particular SX-117 has been completely restored with all new tubes and many capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All switches in this unit have been carefully cleaned using De-Oxit and Q tips and tooth picks to apply the cleaner in small amounts where needed.?? ?,_
--
don??? va3drl
|
Re: SX-117 noise limiter behavior
A noise limiter (usually a diode or two) clips off audio above the strength that the desired audio wave reaches.? Some observers say it should be called a clipper, not a limiter.? Often the ¡°clipping off the peaks¡± threshold is adjustable.? Set the clipping threshold too high and the limiter is relatively ineffective.? Set too low and the audio peaks become clipped and distorted. ?Years ago, the ¡°Twin Noise Squelch¡± was popular with lots of us who operated ten meter and six meter AM mobile.? It provided both a squelch and a noise limiter in one easy-to-build circuit.? In SSB, the audio level is lots more varying, so James Lamb blankers are more effective.? In AM reception, the AVC level tends to hold the recovered (detected) AM audio envelope¡¯s peak values constant, which is valuable for both kinds of noise reduction, but particularly necessary for simple audio noise limiters.
Also ¨C noise limiters are among the group of noise reduction techniques that really only work well on impulse noise where the peak value is quite high compared to the average value (ignition noise).
Mike/
K5MGR
____________________________ ? Mike Langner
929 Alameda Road NW
Albuquerque, NM 87114-1901
(505) 898-3212 home/home office
(505) 238-8810 cell
mlangner@...
?
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From: [email protected] <[email protected]> On Behalf Of Bob
Sent: Friday, June 7, 2024 4:32 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior? A blanker normally reduces pulse type peaks such as spark plug type pulses. Someone else will need to describe a noise limiter. ? So, guys, where is the formal non-partisan definition of.. "noise blanker" "noise limiter" Is there a defined difference between them ? and do the terms define? an intent or a specific circuit? Sorry to interfere but my poor education did not address this; at least not that I remember. ¡»å´Ç²Ô ? I had hoped that someone who has actually seen and used an SX-117 would respond.? I've only been restoring receivers for 40 years or so, but over that time I've learned that you can save a lot of time by consulting with someone else who owns the same radio when observing an odd behavior.? You might be surprised how many times "they all do that" is the undesirable but true answer.? As I said, I have not dug into this particular problem yet.? What I do know is that the SX-117 does not have a "noise blanker" as seen in later or more sophisticated receivers like the Drake R4C.? It is described as a noise limiter.? This particular SX-117 has been completely restored with all new tubes and many capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All switches in this unit have been carefully cleaned using De-Oxit and Q tips and tooth picks to apply the cleaner in small amounts where needed.?? ?,_
--
don??? va3drl
|
Re: SX-117 noise limiter behavior
A blanker normally reduces pulse type peaks such as spark plug type pulses. Someone else will need to describe a noise limiter. Bob W4JFA?
So, guys, where is the formal non-partisan definition of.. "noise blanker" "noise limiter" Is there a defined difference between them ? and do the terms define? an intent or a specific circuit? Sorry to interfere but my poor education did not address this; at least not that I remember. ¡»å´Ç²Ô ? I had hoped that someone who has actually seen and used an SX-117 would respond.? I've only been restoring receivers for 40 years or so, but over that time I've learned that you can save a lot of time by consulting with someone else who owns the same radio when observing an odd behavior.? You might be surprised how many times "they all do that" is the undesirable but true answer.? As I said, I have not dug into this particular problem yet.? What I do know is that the SX-117 does not have a "noise blanker" as seen in later or more sophisticated receivers like the Drake R4C.? It is described as a noise limiter.? This particular SX-117 has been completely restored with all new tubes and many capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All switches in this unit have been carefully cleaned using De-Oxit and Q tips and tooth picks to apply the cleaner in small amounts where needed.?? ?,_
--
don??? va3drl
|
Re: SX-117 noise limiter behavior
So, guys, where is the formal non-partisan definition of.. "noise blanker" "noise limiter" Is there a defined difference between them ? and do the terms define? an intent or a specific circuit? Sorry to interfere but my poor education did not address this; at least not that I remember. ¡»å´Ç²Ô
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Floyd - K8AC
Sent: Friday, June 7, 2024 5:06 PM
To: [email protected]
Subject: Re: [HallicraftersRadios] SX-117 noise limiter behavior? I had hoped that someone who has actually seen and used an SX-117 would respond.? I've only been restoring receivers for 40 years or so, but over that time I've learned that you can save a lot of time by consulting with someone else who owns the same radio when observing an odd behavior.? You might be surprised how many times "they all do that" is the undesirable but true answer.? As I said, I have not dug into this particular problem yet.? What I do know is that the SX-117 does not have a "noise blanker" as seen in later or more sophisticated receivers like the Drake R4C.? It is described as a noise limiter.? This particular SX-117 has been completely restored with all new tubes and many capacitors replaced, as well as a few out-of-tolerance resistors.
Spraying old switch sections with anything is a really bad idea.? All switches in this unit have been carefully cleaned using De-Oxit and Q tips and tooth picks to apply the cleaner in small amounts where needed.?? ?,_ -- don??? va3drl
|
Bob
Mike Langner
Bill (Group Owner)
don Root
Jim Whartenby