Re: L4B Chimney size (K7CBR, VE7RF, WB6KBL)
We both used the? EBM-PAPST? (German made)? squirrel cage blower from the Ameritron AL-1500/AL-1200/ AL-82 amplifier.? ? They came in both a 115 and also a 230 vac version.? Ameritron used the? 115 vac version...and used pri xfmr / buck boost taps to get 3 x different speeds from the blower.
Ameritron used to sell the 115 vac blower for $138.00? then the price went up to $168.00? ? ? At Mouser / Digikey, the 115 vac version was almost $200.00? ? ?For whatever reason, the 230 vac version? at Mouser / DK is $102.00 to $112.00 range.? ?I bought the 230 vac versions, since I needed 4 of em? (for 4 x L4B's).? ?Thought here was..... I have never run those amps on 120 vac.?
The mod however does require metal work, since the blower exhaust dimensions are bigger than the drake blower.? ?The new blower has flanges on the exhaust and one of em has to be cut off in my bandsaw.? ?The intake opening is bigger than oem, and slightly offset too.?
I did not have the anemometer, but guesstimated the airflow? on the papst blower to be a bare? minimum of double.? ?My estimate was? between 2.25? and 2.5 X? more airflow.? ?By using a? drop resistor in one leg, any speed can be obtained.? The drop resistor can also be shunted on TX.? ?Then it's quieter on RX....and extended RX.? That's an experiment in progress.?
?
|
Re: L4B Chimney size (K7CBR, VE7RF, WB6KBL)
Hello Clayton,
This was all done so long ago I can't recall, yet that information was posted to the Drake board here. Jim (VE7RF) used a different blower (same housing yet 230VAC) I think. If I had to guess, I order parts mostly from Mouser, DigiKey, and Newark, so likely came from one of those. Know that if you do this, You will need to relocate the inlet, enlarge the discharge port in the horizontal chassis, and make some minor changes to the new blower mounting flange to make it fit properly with the glass chimney. Is it worth the trouble? YES! You only need to do it once. This type of blower (compact air over induction motor) did not exist in this size and style when Drake built this amplifier. I attached photo's from my archive to show you in case you did not see them some years ago. If you have issues locating the part number, I can look inside my L4B this weekend and post the part number here for you. --Joseph
On Monday, December 23, 2024 at 09:29:12 PM EST, Clayton kk4iz via groups.io <kk4iz284@...> wrote:
Joseph Where did you get your fan motor for your Drake L4B? Part numbers and cost?
Merry Chirstmas 73¡±²õ
On Dec 18, 2024, at 11:16?AM, Joseph K7CBR via groups.io <k7cbr@...> wrote:
The new blower moves over twice the air of the factory blower through the same sk406 chimney. I did the direct comparison using a hand held anemometer... held at the same location and distance above the outlet of the SK-406 chimney. I forgot now what the original velocity and CFM values vs. new ones were/are. I measured this to avoid any confirmation bias. It was nice to see Jim (VE7RF) confirming my findings. As I stated a long time ago, it is not enough to have one person just say it/measure it. Even though I was careful to do empirical measurement.
Tuesday, December 10, 2024 at 11:33:34 AM EST, Richard Knoppow via groups.io <1oldlens1@...> wrote:
? ? ? Does changing the idle current affect the distortion? If this is
the grid bias with no drive it is the operating point of the amplifier.
If I understand what you are doing correctly (and I may well not be) the
bias establishes the operating point of the amplifier so increasing bias
toward cut off, i.e. more negative, moves the amplifier toward Class B.
That would certainly reduce dissipation in the absence of drive.
? ? Another thought: Does not the tapering of the chimney at the top
restrict air flow? It should increase velocity at the plate seal but is
a constriction so might reduce overall air flow. Maybe there is
something here I am not getting.
On 12/10/2024 7:46 AM, Jim VE7RF via groups.io wrote:
> On Mon, Dec 9, 2024 at 05:17 PM, Joseph K7CBR wrote:
>
>? ? <Well Senor Jim... I was wondering if you had made the change yet on
>? ? the L4B... .. What was the before and after result? Cooling, noise,
>? ? and so on...
>
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
73¡¯²õ
KK4IZ
Amateur Radio Operator
Warren Bryant?
124 Crestview Dr
Clanton,AL.??35045
Email:?KK4IZ284@...
Cell: 205-389-4170
|
On Tue, Dec 24, 2024 at 01:31 AM, Thomas W9TAB wrote:
<AGC in the Drake amp is developed from the transmitters ¡°input¡± to the tube(s)
<When you key the transmitter it doesn¡¯t see the AGC signal until it goes through the comparison circuit then develops the required negative DC voltage to pull back the RF coming from the transmitter.
<So there is a reoccurring front end RF spike that is pulled back by the AGC circuit each time you key the transmitter as the AGC voltage disappears during receive.
<AGC control process is ¡°Sample, compare, voltage generation, then transmitter output reduction¡± each time you key the transmitter.
<If you set the AGC voltage to cut the transmitters output to 60watts (In the example of my L7) I get 1000watts carrier out.
<Looking at the output on a scope the signal is nice and clean with a two tone audio for a test signal and transmitting into a dummy load.
IOW,? you are closing the barndoor......after the horse has bolted, and every time you trip the VOX on SSB.? ? And the ALC time constant in the amplifier has to match the ALC time constant in the xcvr / tx.? Drake had a tech note out about matching the time constants if using a T4XC with a L7....or using a? TR7? with an L4B.? It was? a cap / resistor change.? ?The mic gain in the T4XC is not a PO control....when using SSB.?? The advantage of using the external, adjustable DCV method is..... the ALC voltage has already been developed, and is sitting there all the time, at a constant level.? ?The drawback is, if whispering into the mic, you won't get desired PO out of the T4XC / XCVR. If an external processor is used, or external audio compressor / gating system used, or a boom headset used,? it's a non issue.? Where you would really get into trbl, is when using a TR7 / T4XC on SSB mode, and try and drive an amp that requires very little drive, like most of the SS amps.? You are putting out 130 watts pep initially from the T4XC, until the derived ALC voltage developed in the SS amplifier, is sent back to the TX / XCVR.? On the Merc-3 SS amp, it has a built in event counter, and will know asap, if you ever applied > 60 watts pep into the amp.....warranty denied. If that 5K @ 7 watt resistor below the chassis in the L4PS / L7PS opens up, you will end up with full B+ on the ALC adjustment pot in the L4B / L7.? In my case, the 7K pot, along with the pair of 50K bleeders was tossed, to reduce heat in the L4PS.? Since the yaesu xcvr already has adjustable PO, it's a non issue.? Still, the external DCV can still be used, if the SS xcvr has the dreaded overshoot / initial spike issue...typ of some of the Icom xcvrs, like local buddy's? ICOM? 775DSP, which puts out a 200 watt spike, regardless of? where the PO is set at....which wreaks havoc when driving his Ameritron AL-80B, single 3-500Z amp.? The ICOM 706MK2 series also put out a 140 watt spike, again regardless of where the PO is set.? ?A few other SS xcvr's have a similar issue, to varying degrees.? On a? sorta related sidenote,? I just ordered a? 40 kv? HV probe.? ?It uses a long, large value resistor, in series with a low value resistor.? Cold end of low value resistor is clipped to the B- of the HV supply...via it's 3' test lead + clip.? ? The V drop across the lower valued resistor is fed to my fluke 87 DVM...via a 2 x conductor cable.....with dual plug assy.? ? ?40 kv dc? will be? 40.0 vdc on the? DVM.? (1000:1 ratio).? 2650 vdc? will be 2.65 vdc on the fluke 87.? IF that return test lead ( that goes to the B- of the supply)? ever opened up / fell off....... the full B+ will then appear on the fluke 87 DVM.? This freaks me out.?
|
Re: Drake L7 10m modification
Roger,
To my knowledge Drake used 3 different schemes to lockout 10/11 meters from the CB crowd. ?The one you have sounds like the one where there is a round head screw with/without a nut, something like a cap screw, possibly with an Allen head. ?The best way to remove it, I've found, is to do it from the bottom. ? However, ?do be careful and stuff some painters tape, or kleenex, ?or something "below" where that screw/nut might fall. ?That way you can capture it before it gets into some known/unknown location that could cause further damage upon power up. ?For me, I've found that needle nose pliers worked well with high illumination.
But let's hear what the experts say.
Best of luck.
73,
Evan, K9SQG
I've looked down in the band switch from the bottom and see a small nut. I can't really see the head. What is the best way to get at it? Top or bottom? What type of tools did you use? Going in from the bottom is extremely tight.?
|
Re: Drake L7 10m modification
I've looked down in the band switch from the bottom and see a small nut. I can't really see the head. What is the best way to get at it? Top or bottom? What type of tools did you use? Going in from the bottom is extremely tight.?
|
Re: L4B Chimney size (K7CBR, VE7RF, WB6KBL)
Joseph Where did you get your fan motor for your Drake L4B? Part numbers and cost?
Merry Chirstmas 73¡±²õ
On Dec 18, 2024, at 11:16?AM, Joseph K7CBR via groups.io <k7cbr@...> wrote:
The new blower moves over twice the air of the factory blower through the same sk406 chimney. I did the direct comparison using a hand held anemometer... held at the same location and distance above the outlet of the SK-406 chimney. I forgot now what the original velocity and CFM values vs. new ones were/are. I measured this to avoid any confirmation bias. It was nice to see Jim (VE7RF) confirming my findings. As I stated a long time ago, it is not enough to have one person just say it/measure it. Even though I was careful to do empirical measurement.
Tuesday, December 10, 2024 at 11:33:34 AM EST, Richard Knoppow via groups.io <1oldlens1@...> wrote:
? ? ? Does changing the idle current affect the distortion? If this is
the grid bias with no drive it is the operating point of the amplifier.
If I understand what you are doing correctly (and I may well not be) the
bias establishes the operating point of the amplifier so increasing bias
toward cut off, i.e. more negative, moves the amplifier toward Class B.
That would certainly reduce dissipation in the absence of drive.
? ? Another thought: Does not the tapering of the chimney at the top
restrict air flow? It should increase velocity at the plate seal but is
a constriction so might reduce overall air flow. Maybe there is
something here I am not getting.
On 12/10/2024 7:46 AM, Jim VE7RF via groups.io wrote:
> On Mon, Dec 9, 2024 at 05:17 PM, Joseph K7CBR wrote:
>
>? ? <Well Senor Jim... I was wondering if you had made the change yet on
>? ? the L4B... .. What was the before and after result? Cooling, noise,
>? ? and so on...
>
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
73¡¯²õ
KK4IZ
Amateur Radio Operator
Warren Bryant?
124 Crestview Dr
Clanton,AL.??35045
Email:?KK4IZ284@...
Cell: 205-389-4170
|
ALC overshoot spikes are minimal if ALC is used as intended. ALC is not a speech processing system nor a hard limiter. It is there to catch those occasional higher peaks. Thus the instruction with the TR7 to adjust mic gain so the ALC LED only flashes on occasional peaks. In bench testing a TR7 some years back with a peak reading Wattmeter I had to hit it pretty hard to generate significant overshoot peaks. The conclusion was that if you are seeing significant overshoot then you are overdriving your audio. I have been using amp ALC for years with L4B, L7, NCL-2000, and now an Alpha 76 and it works as desired if used as intended. 73 -Jim NU0C On Tue, 24 Dec 2024 00:31:05 +0000 "Thomas W9TAB via groups.io" <electron@...> wrote: AGC in the Drake amp is developed from the transmitters ¡°input¡± to the tube(s)
When you key the transmitter it doesn¡¯t see the AGC signal until it goes through the comparison circuit then develops the required negative DC voltage to pull back the RF coming from the transmitter.
So there is a reoccurring front end RF spike that is pulled back by the AGC circuit each time you key the transmitter as the AGC voltage disappears during receive.
AGC control process is ¡°Sample, compare, voltage generation, then transmitter output reduction¡± each time you key the transmitter.
If you set the AGC voltage to cut the transmitters output to 60watts (In the example of my L7) I get 1000watts carrier out.
Looking at the output on a scope the signal is nice and clean with a two tone audio for a test signal and transmitting into a dummy load.
Tom W9TAB
On Dec 23, 2024, at 2:04?PM, Tony N5DIM <tony@...> wrote:
?Thank you everybody for the info. I will definitely check and use the information in the manual. Also scored the speech processor today also. Merry Christmas and 73. Tony N5DIM
On Dec 23, 2024, at 9:34?AM, Jim Shorney via groups.io <jimNU0C@...> wrote:
?
I don't see an advantage to that. Adjustable ALC is right there in the amp and you are adjusting it to what is happening at the amp, not to an arbitrary value.
On Mon, 23 Dec 2024 16:47:22 +0000
"Thomas W9TAB via groups.io" <electron@...> wrote:
You can also ditch the ALC in the amp and use an adjustable negative low voltage source to the radio.
Several simple circuits are out there, some using a 9vdc battery and a potentiometer and others using a Walwart.
The amps ALC setting not only varies with band selection but also changes when you switch from CW to SSB
Tom W9TAB -- 73 -Jim NU0C
|
AGC in the Drake amp is developed from the transmitters ¡°input¡± to the tube(s)
When you key the transmitter it doesn¡¯t see the AGC signal until it goes through the comparison circuit then develops the required negative DC voltage to pull back the RF coming from the transmitter.
So there is a reoccurring front end RF spike that is pulled back by the AGC circuit each time you key the transmitter as the AGC voltage disappears during receive.
AGC control process is ¡°Sample, compare, voltage generation, then transmitter output reduction¡± each time you key the transmitter.
If you set the AGC voltage to cut the transmitters output to 60watts (In the example of my L7) I get 1000watts carrier out.
Looking at the output on a scope the signal is nice and clean with a two tone audio for a test signal and transmitting into a dummy load.
Tom W9TAB
toggle quoted message
Show quoted text
On Dec 23, 2024, at 2:04?PM, Tony N5DIM <tony@...> wrote:
?Thank you everybody for the info. I will definitely check and use the information in the manual. Also scored the speech processor today also. Merry Christmas and 73. Tony N5DIM
On Dec 23, 2024, at 9:34?AM, Jim Shorney via groups.io <jimNU0C@...> wrote:
?
I don't see an advantage to that. Adjustable ALC is right there in the amp and you are adjusting it to what is happening at the amp, not to an arbitrary value.
On Mon, 23 Dec 2024 16:47:22 +0000
"Thomas W9TAB via groups.io" <electron@...> wrote:
You can also ditch the ALC in the amp and use an adjustable negative low voltage source to the radio.
Several simple circuits are out there, some using a 9vdc battery and a potentiometer and others using a Walwart.
The amps ALC setting not only varies with band selection but also changes when you switch from CW to SSB
Tom W9TAB
--
73
-Jim
NU0C
|
Nice catch. The 7805 is normally very reliable but they do fail occasionally especially in older gear. I trust you checked for a short on the output. I would think you would still have output power without bias. It would be operating Class B with lots of crossover distortion. More like a tad into Class C. On Mon, 23 Dec 2024 14:24:13 -0800 "Craig W8CS via groups.io" <craig_severson@...> wrote: I think I found the issue.
There is a switched +13.6V line from the T/R relay which goes to a 7805 regulator on the power amp board. I get switched +13.6V in from the relay to the input of that regulator, and nothing out.
I think that this switched 5V supply runs the final amp bias circuit.
I'll order some 7805's and let you guys know if that's the culprit next week.
--
Craig/W8CS
Greenville, SC -- 73 -Jim NU0C
|
I think I found the issue.?
?
There is a switched +13.6V line from the T/R relay which goes to a 7805 regulator on the power amp board. I get switched +13.6V in from the relay to the input of that regulator, and nothing out.?
?
I think that this switched 5V supply runs the final amp bias circuit.?
?
I'll order some 7805's and let you guys know if that's the culprit next week.?
--
Craig/W8CS
Greenville, SC
|
Thank you everybody for the info. I will definitely check and use the information in the manual. Also scored the speech processor today also. Merry Christmas and 73. Tony N5DIM
toggle quoted message
Show quoted text
On Dec 23, 2024, at 9:34?AM, Jim Shorney via groups.io <jimNU0C@...> wrote:
?
I don't see an advantage to that. Adjustable ALC is right there in the amp and you are adjusting it to what is happening at the amp, not to an arbitrary value.
On Mon, 23 Dec 2024 16:47:22 +0000
"Thomas W9TAB via groups.io" <electron@...> wrote:
You can also ditch the ALC in the amp and use an adjustable negative low voltage source to the radio.
Several simple circuits are out there, some using a 9vdc battery and a potentiometer and others using a Walwart.
The amps ALC setting not only varies with band selection but also changes when you switch from CW to SSB
Tom W9TAB
--
73
-Jim
NU0C
|
Jim Thanks for that tip as I found that the 5 volt 7805 regulator was dead on the side wall by the power supply.. Installed a new one and things are working now even the receiver hears signals. I don't have an antenna up right now as I am putting up a tower as I only managed to get the bottom section and in concrete. Display works and so does the receiver. Having trouble with the relay on the back left side not working well to go from receive to transmit. So that will be my next job on it. Thanks to all for the help as I really appreciate it.
73, Jim VE1RB
toggle quoted message
Show quoted text
On 2024-12-20 22:41, Jim Shorney via groups.io wrote: Check all voltages. You have two 5 volt regulators on the sidewall. One powers the counter and one powers the LED display. They are fed from the 4 pin Molex near the right edge of the board. R9092 ( 5 Ohm 5W ) is another suspect. Side note, there is no "backwards" for the four pin Molex. Drake cleverly wired it so it will work either way.
On Fri, 20 Dec 2024 20:34:46 -0400
"Jim Harris via groups.io" <radiove1rb@...> wrote:
Thanks Mike for the reply. I have checked a lot of the IC's and they do
have 5 volts VCC on them but will check them all. Maybe one does not. The
NORM/EXT switch on the back does not do anything. they display is black and
it stays that way. I will let you know what I find out.
73, Jim VE1RB
|
Re: Wanted: 1500 Hz filter (Noble FILTERS)
Some fair points in your statements. Yes all filters will eventually fail, yet many will be doing this outside of the current life expectancy of the users. Mechanical filters fail, crystal filters fail, and no the sky is not falling... I mentioned this as something to look out for and if there is any due diligence on this subject? It would be much better to start with new. Drake ran these filters in equipment that held a high ambient temperature, so this can accelerate aging in these devices. Perhaps everyone is so used to discussing things in terms of it's "black" or "white" that assumptions are made as such. In the last 30 years, I have had two mechanical filters fail and three crystal filters fail. Failure modes vary from excess loss, to excess ripple, passband shift or distortion, a DC blocking failure, it makes no difference. We still need a replacement.
On Monday, December 23, 2024 at 12:11:08 PM EST, Jeff AC0C <keepwalking188@...> wrote:
I don't want to pick nits here but the statement that all filters
will fail, and it "could be now" is just not setting the
expectations properly.? I agree that some filters do fail over
time for a variety of reasons, but my experience is that most
filters will live longer than the gear remains operational
otherwise.? And when gear breaks, from a "things that will likely
die first in old gear" - a crystal filter is not remotely near the
top of that list by a long shot.??
Casual readers on the reflector may get the impression from this
claim that filter failures occur more than it does simply because
this reflector has a much higher concentration of guys doing
restoration work.? That does not comprehend the far greater number
of guys with a Drake (or other older radio) sitting on their desk
that has given great service over the years and continues to work
today.?
Maybe some of the old hands at Drake gear may have a specific
exception to this.? Here I'm reminded of the Yaesu bias applied to
the old Murata filters which did lead to many of them dying over
time - not a filter fault per se, but rather a failure by Yaesu to
DC isolate the filter, as an example.
73/jeff/ac0c
alpha-charlie-zero-charlie
On 12/23/2024 7:55 AM, Steve Wedge,
W1ES/4 via groups.io wrote:
I
don't need one at the moment but I'd be willing to get a new 600
Hz filter for my TR-4cW RIT.? I actually had one in another rig
fail and I was fortunate enough to be able to take it apart and
fix it using the baking method but these do fail? Are there any
other TR-4cW owners who would be willing to do this?
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Monday, December 23rd, 2024 at
8:17 AM, Joseph K7CBR via groups.io
<k7cbr@...> wrote:
Hello,
He can make almost any
filter, however there needs to be enough demand to allow
him to acquire materials and put some profit margin into
the task!
For one two or three
units? It wont happen. It is important for everyone to
recognize that at some point, crystal filters are going to
fail. Could be now, or years from now. Many times small
changes can be compensated for in the alignment process,
yet there is a limit. I have had a couple failed filters
in my Drake equipment over the years. For filters
available through Noble Radio? They are decent! I can't
say enough good about them. Consider that there is nowhere
else to go if you need one. Installing a "used" filter
puts you right back where you started in the quartz
oscillator/capacitor aging process.
If enough people need
filters, lets sign up, get some quantity demand going,
perhaps commit with a 50% deposit, and see if Frank can
make something. I would be willing, as I know where this
is heading in the next few years.
Thanks,
Joseph
On Saturday, December 21, 2024 at 09:10:11 PM EST,
Bob Loving <bob.loving@...> wrote:
Makes me wonder if Frank could
produce a new 48.050-MHz filter for the TR7.?
Bob K9JU
On Saturday, December 21, 2024 at 07:54:23
PM EST, Floyd - K8AC via groups.io
<floydsense@...> wrote:
Frank made up a 1500 Hz filter for me
and just received it today.? Works
perfectly.? I highly recommend Noble
Radio for filters.
?
73, Floyd - K8AC
|
Welcome back! Your first check should be the high current 13.6V pin on the PS7 4-pin connector. It powers the PA deck and if there is a problem there you will have no output. Otherwise, a rig that has been idle that long may have some "Molexia". Grab a cup of coffee and see: /g/DRAKE-RADIO/search?p=recentpostdate%2Fsticky%2C%2C%2C20%2C2%2C0%2C0&q=molexiaOn Mon, 23 Dec 2024 10:10:59 -0800 "Craig W8CS via groups.io" <craig_severson@...> wrote: Hello all, new to the group. Getting back on the air after a twenty-year hiatus starting a business and raising a family.
First order of business is to get the TR-7A back on the air. Remarkably the PS-7 is still fine and voltage output looks good.
The unit receives fine and everything appears to work with the exception of no transmit power. I can hear a transmit signal (CW or SSB) in my R-4C but no output indicated on the meter, and the green ALC LED does not light up.
I do have the service manual. I'm about to start the process of breaking this problem down, but thought I would query the group for advice and common issues first. -- 73 -Jim NU0C
|
Noble is pretty good at answering email and explaining specs. I ordered the set for my "new" R4C...(AM,? 3 CW,? SSB)? still learning and haven't installed the SSB filter yet, but glad I got the CW filters going. Cost is much better than the stock Drake filters on E-pay. 73? Jay W6CJ
I have finally gotten my R4-c working and I am considering the IF filter upgrade that Rob used to provide. Is Noble the best source for it and if so do they have the specs for it. If not, can someone pass them on to me?
Thanks,
Bill N0CU
--
Bill N0CU
|
Hello all, new to the group. Getting back on the air after a twenty-year hiatus starting a business and raising a family.?
?
First order of business is to get the TR-7A back on the air. Remarkably the PS-7 is still fine and voltage output looks good.?
?
The unit receives fine and everything appears to work with the exception of no transmit power. I can hear a transmit signal (CW or SSB) in my R-4C but no output indicated on the meter, and the green ALC LED does not light up.?
?
I do have the service manual. I'm about to start the process of breaking this problem down, but thought I would query the group for advice and common issues first.?
?
Thanks in advance....?
--
Craig/W8CS
Greenville, SC
|
I don't see an advantage to that. Adjustable ALC is right there in the amp and you are adjusting it to what is happening at the amp, not to an arbitrary value. On Mon, 23 Dec 2024 16:47:22 +0000 "Thomas W9TAB via groups.io" <electron@...> wrote: You can also ditch the ALC in the amp and use an adjustable negative low voltage source to the radio.
Several simple circuits are out there, some using a 9vdc battery and a potentiometer and others using a Walwart.
The amps ALC setting not only varies with band selection but also changes when you switch from CW to SSB
Tom W9TAB -- 73 -Jim NU0C
|
I have finally gotten my R4-c working and I am considering the IF filter upgrade that Rob used to provide. Is Noble the best source for it and if so do they have the specs for it. If not, can someone pass them on to me?
Thanks,
Bill N0CU
--
Bill N0CU
|
Re: Wanted: 1500 Hz filter (Noble FILTERS)
I don't want to pick nits here but the statement that all filters
will fail, and it "could be now" is just not setting the
expectations properly.? I agree that some filters do fail over
time for a variety of reasons, but my experience is that most
filters will live longer than the gear remains operational
otherwise.? And when gear breaks, from a "things that will likely
die first in old gear" - a crystal filter is not remotely near the
top of that list by a long shot.??
Casual readers on the reflector may get the impression from this
claim that filter failures occur more than it does simply because
this reflector has a much higher concentration of guys doing
restoration work.? That does not comprehend the far greater number
of guys with a Drake (or other older radio) sitting on their desk
that has given great service over the years and continues to work
today.?
Maybe some of the old hands at Drake gear may have a specific
exception to this.? Here I'm reminded of the Yaesu bias applied to
the old Murata filters which did lead to many of them dying over
time - not a filter fault per se, but rather a failure by Yaesu to
DC isolate the filter, as an example.
73/jeff/ac0c
alpha-charlie-zero-charlie
On 12/23/2024 7:55 AM, Steve Wedge,
W1ES/4 via groups.io wrote:
toggle quoted message
Show quoted text
I
don't need one at the moment but I'd be willing to get a new 600
Hz filter for my TR-4cW RIT.? I actually had one in another rig
fail and I was fortunate enough to be able to take it apart and
fix it using the baking method but these do fail? Are there any
other TR-4cW owners who would be willing to do this?
73,
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Monday, December 23rd, 2024 at
8:17 AM, Joseph K7CBR via groups.io
<k7cbr@...> wrote:
Hello,
He can make almost any
filter, however there needs to be enough demand to allow
him to acquire materials and put some profit margin into
the task!
For one two or three
units? It wont happen. It is important for everyone to
recognize that at some point, crystal filters are going to
fail. Could be now, or years from now. Many times small
changes can be compensated for in the alignment process,
yet there is a limit. I have had a couple failed filters
in my Drake equipment over the years. For filters
available through Noble Radio? They are decent! I can't
say enough good about them. Consider that there is nowhere
else to go if you need one. Installing a "used" filter
puts you right back where you started in the quartz
oscillator/capacitor aging process.
If enough people need
filters, lets sign up, get some quantity demand going,
perhaps commit with a 50% deposit, and see if Frank can
make something. I would be willing, as I know where this
is heading in the next few years.
Thanks,
Joseph
On Saturday, December 21, 2024 at 09:10:11 PM EST,
Bob Loving <bob.loving@...> wrote:
Makes me wonder if Frank could
produce a new 48.050-MHz filter for the TR7.?
Bob K9JU
On Saturday, December 21, 2024 at 07:54:23
PM EST, Floyd - K8AC via groups.io
<floydsense@...> wrote:
Frank made up a 1500 Hz filter for me
and just received it today.? Works
perfectly.? I highly recommend Noble
Radio for filters.
?
73, Floyd - K8AC
|
You can also ditch the ALC in the amp and use an adjustable negative low voltage source to the radio.
Several simple circuits are out there, some using a 9vdc battery and a potentiometer and others using a Walwart.?
The amps ALC setting not only varies with band selection but also changes when you switch from CW to SSB?
Tom W9TAB?
toggle quoted message
Show quoted text
On Dec 23, 2024, at 10:16?AM, Evan via groups.io <k9sqg@...> wrote:
?
As a side note, the ALC on the L75 is similar to the L7 and L4B in that it is frequency sensitive. ?Adjusting it for 10-15 meters, for example, will result in overdrive if switching to 80 or 160 without re-adjusting it. ?The
circuits in these amps are not identical but the function is the same.
Tony,
The manual for the L-75 provides all of the information you should need for connecting and operating the TR-7 with the L-75.? Refer to connection diagrams and section on "SSB Tuning and Operation."? As Jim pointed out, the L75 has amplifier ALC, which is adjusted
by a front panel control labeled "AGC."
Enjoy the new amp.
Jerry, N4JL
-----Original Message-----
From:
[email protected] < [email protected]> On Behalf Of Jim Shorney via groups.io
Sent: Monday, December 23, 2024 2:13 AM
To:
[email protected]
Subject: Re: [DRAKE-RADIO] L75 amplifier /TR-7
Use amplifier ALC and your mic gain to control the drive.
On Sun, 22 Dec 2024 21:53:35 -0800
"Tony N5DIM via groups.io" <tony@...> wrote:
> Hello everyone. I¡¯m picking up a L75 tomorrow. My TR7 is running around 120-140 PEP. If I need to reduce drive power to amplifier is the only way the WB4HFN mod to alc?? When the amplifier spec¡¯s a 50-80 watt drive is that average watts or PEP? Thanks for
any answers. Tony N5DIM
--
73
-Jim
NU0C
|
Jim Shorney
Thomas W9TAB
Craig W8CS
Jay W6CJ