It's called the audio$fool effect.?
? ? I don't actually know but suspect they are the same. Pillow stuffing
would work OK and is likely cheaper. Anything sold for audio seems to
become expensive.
On 1/2/2025 1:56 PM, Stan Gammons via wrote:
> I've wondered if the Acousta-Stuf? Polyfil is the same as the Poly-Fil
> pillow stuffing one can buy at Walmart?
>
> 73
>
> Stan
> KM4HQE
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
|
Re: Sources for T4XC final tubes?
Oh, shoot!? I meant to add that in.? The joys of using a phone without a real keyboard...
Very important if you're buying these tubes from someone who doesn't know about this (and it's the main reason that 6GJ5's get rejected as a replacement).
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with secure email.
On Friday, January 3rd, 2025 at 2:01 PM, David via groups.io <david.w5xu@...> wrote:
Please note that all 6JB6 tubes are not the same. There are several out there that are about 1/2 inch + longer than those supplied with the radios. These will not allow the top of the EF cage to be used. I am not sure but I think RCA is in that arena. So, while you consider the available alternatives, consider how tall they are. David Assaf III W5XU, VP8RXU
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
On Friday, January 3, 2025 at 12:20:11 PM EST, Jay W6CJ via <lastradioman= [email protected]> wrote:
Group, I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair? (I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73, Jay W6CJ
|
So Dan the Collins is a direct replacement for the Drake?
? ? ?Frank Krozel ? ? ? ? ? ?KG9H Life Member, ARRL ? ? (630) 924-1600 kg9hfrank@...
toggle quoted message
Show quoted text
On Jan 3, 2025, at 2:31?PM, Dan via groups.io <pitfit@...> wrote:
I believe this is the one you mean. You have to scroll way down and it is on the left hand side.
Dan WB4GRA
<image1.jpeg>On Jan 3, 2025, at 3:11?PM, n4buq <n4buq@...> wrote:
? I thought this was in reference to Surplus Sales' (COL) SPKR-4-57 on https://www.surplussales.com/Microphones-Audio/MicroAudio-8.html.? Is that incorrect? 73, Barry - N4BUQ Mark, went to the site, but no speaker comes up with your speaker information.? Wrong part number perhaps?? Joe ¨C W7RKN (Ahhhhhh¡¡just did a search for MS4 speakers¡.sold out!....MS4, RV4, SPR4, C4 5.5 x 10.75 x 12.5 SOLD OUT) From:?[email protected] [mailto:[email protected]]?On Behalf Of?Mark - WB0IQK via groups.io
Subject:?Re: [DRAKE-RADIO] Speaker? ?
I've been replacing my MS-4 speakers with an exact replacement that Surplus Sales sells.? MS-4 SPEAKER REPLACEMENT ( Misco #JC57CD ) Sold as a Collins Replacement:
Surplus Sales of Nebraska, 1218 Nicholas Street, Omaha, NE 68102, Phone: (402)?
346-4750, Part #: (COL) SPKR-4-57,?
Web:?
|
Drake T-4XC, R-4C and other items for sale
I have been helping a non-ham friend sell these items, who inherited them from his dad (Billy Lott, W5TW, Tuscaloosa, AL).
These items have not sold, so he asked me to reduce the cost further.
T-4XC Transmitter / R-4C Receiver / MS-4 Speaker/Power Supply $795
MS-4 Speaker $40 (This is a separate speaker only from the above speaker which contains the power supply)
I previously advertised the following non-Drake items on the reflector, and no one said that was not OK, and have also reduced the price of these items in an effort to sell them.
Ameritron ATR-30 Antenna Tuner in very good condition $200
Sencore FC-45 ?Frequency Counter $50
Sencore DVM-38 $50
Astron RS-35 $40
Kenwood SM-20 Scope with Pan adapter $100
Kenwood SP-31 Speaker $40
Central Electronics Multi Phase RF Analyzer $75?
Microphone $50
I can send additional photos for any item(s) in which you are interested. Prices are asking, offers will be considered.?Items are located in Oviedo, FL (near Orlando)Please send me a message directly to my email (eric.jorgensen@...) for any item(s) you are interested in.
This equipment is in reasonable cosmetic condition, but I cannot test it. ?If desired, a video call can be set up to go over the Drake receiver or transmitter.
I will ship for the exact cost of shipping, using PayPal shipping. ?Or the items can be picked up in Oviedo, FL.
Payment made by PayPal. After purchase, a separate PayPal payment to be made for actual, exact, precise PayPal shipping cost. No PayPal fee.
Kindly do not ask me to calculate shipping cost, as that can only be calculated after the item is packed and the exact dimensions, weight and destination are known. ?I will only charge the exact shipping fee that PayPal charges me.
Thanks,
Eric Jorgensen W1NEJ Boca Raton, FL
|
Joe - W7RKN via groups.io writes: Probably would have helped if the correct URL had been posted:
.surplussales.com/class/brand/drakmusemeqp.html. And if select the "purchasing info" button on that link it leads to a 404 not found error :-( --lyndon
|
Digital readout for Drake
Happy and a Safe New Year to All!
?
Purchased a B line a few years ago and a frequency readout came along with it. It was manufactured by Cobra-Freq Co. Did a search on the Internet and could not locate anything. Has anyone heard or used this particular unit?
john w3khg
|
Probably would have helped if the correct URL had been posted:? . ? Joe - W7RKN ? I thought this was in reference to Surplus Sales' (COL) SPKR-4-57 on https://www.surplussales.com/Microphones-Audio/MicroAudio-8.html.? Is that incorrect? 73, Barry - N4BUQ
toggle quoted message
Show quoted text
Mark, went to the site, but no speaker comes up with your speaker information.? Wrong part number perhaps?? Joe ¨C W7RKN (Ahhhhhh¡¡just did a search for MS4 speakers¡.sold out!....MS4, RV4, SPR4, C4 5.5 x 10.75 x 12.5 SOLD OUT)
|
I believe this is the one you mean. You have to scroll way down and it is on the left hand side.
Dan WB4GRA
toggle quoted message
Show quoted text
On Jan 3, 2025, at 3:11?PM, n4buq <n4buq@...> wrote:
? I thought this was in reference to Surplus Sales' (COL) SPKR-4-57 on https://www.surplussales.com/Microphones-Audio/MicroAudio-8.html.? Is that incorrect? 73, Barry - N4BUQ Mark, went to the site, but no speaker comes up with your speaker information.? Wrong part number perhaps?? Joe ¨C W7RKN (Ahhhhhh¡¡just did a search for MS4 speakers¡.sold out!....MS4, RV4, SPR4, C4 5.5 x 10.75 x 12.5 SOLD OUT) From: [email protected] [mailto:[email protected]] On Behalf Of Mark - WB0IQK via groups.io
Subject: Re: [DRAKE-RADIO] Speaker? ? I've been replacing my MS-4 speakers with an exact replacement that Surplus Sales sells.? MS-4 SPEAKER REPLACEMENT ( Misco #JC57CD ) Sold as a Collins Replacement:
Surplus Sales of Nebraska, 1218 Nicholas Street, Omaha, NE 68102, Phone: (402)?
346-4750, Part #: (COL) SPKR-4-57,?
Web:
|
Re: T-4XC has a "condition"
Dean:
The RF Tune has a "0" at the point when the knob is rotated LEFT (counter-clockwise) just at?the end of the 160 Band mark.? That's not a "0" at the CW end of the dial....it's a "10".? It's on the high side of the line opposite the "10m Band marking".
By asking you to set the TUNE, LOAD, RF Tune, and GAIN controls all CCW....or at zero....they are trying to ensure there is absolutely NO RF getting into the PA tubes?to "bolster" the bias setpoint.? In reality, as long as the GAIN control is all the way CCW...at zero....you are likely OK to set the bias...although maybe not in that rig.....but FWIW....follow the procedure.? Set RF TUNE control CCW to the "0".
I can't experiment with one of my own rigs today or tomorrow, but I'll be able to do that likely on Sunday.? I am now anxious to see if I can duplicate what you are seeing with the RF Tune rotated clockwise into the high end of the 10m band setting.
73...and more?to follow on this in a few days.
Peter VE7PS
Peter,?
Thanks again for the comments. I need to clarify one issue.?
If you look at the RF Tune control knob. Clockwise there is a small 0. Counter clockwise?there i a 0. The instructions to set the bias say to put the pointer on 0. Which 0?
I tried to set the bias both ways. Pointed at the CC 0 I can lower the needle to the tick mark. If I use the CcC 0 I can only lower the current to .300.?
At this point I don¡¯t think it¡¯s the transmitter. I believe the power supply has a bias problem.?
Thoughts?
Dean
Dean....you wrote....
OK guys,
?
Here is an observation. I just cleaned the power connection and decided to check the bias again. All knobs turned to ¡°0¡±. Now, on the RF tune I see a ¡°0¡± in the 10 meter section.
At this point I can get the bias to the tick mark. Now I see another ¡°0¡± in the 160 meter range. The lowest bias setting here is .3 amps
?
With the bias set now the tune procedure is closer to what I see on videos and I get a grid dip. But for normal operation all knobs are fully CW.
?
Dean
Sorry but I am losing you here with some of your statements about the "zero" you are getting at 10m and 160.? What "zero" are you talking about?
Start on 40m. Mode switch in SSB position. Band switch?set on 40m.? Plate Tune about 10 o'clock....Load about 10 o'clock.? RF Tune set at 40m.? RF wattmeter in line on the transmitter
output to a 50 ohm dummy load.? GAIN Control set?AT ZERO - all the way
counter-clockwise!!!!!!
Key up the T-4XC with a microphone?PTT? and no audio.....OR put the Mode switch into TUNE.? ?Adjust?the bias pot on AC-4 power supply to set at 70 ma (the tick mark) on
the T-4XC plate current meter.
If that goes OK, then switch the MODE switch to TUNE and increase the GAIN control until you see the meter rise slightly, then peak that reading with the RF Tune control.?
You should see some output on the wattmeter. Quickly peak the PLATE control for maximum output, which should correspond pretty closely to a dip in the PLATE CURRENT.? Increase the load control from the 10 o'clock position slightly, and increase?GAIN slightly,
then dip the Plate Current again to a minimum with the PLATE control. Increase the GAIN control again and do all that once more.? Keep that process?up until you have about 250-300mA Plate current when the Plate control is dipped and output is at about 120w
or so.? Keep the transmissions?short...allow cooling time if needed...which is likely as a beginner.? This whole process becomes much quicker with practice!
You will find that the LOAD control needs to be at around 10 o'clock?for 80/40m and maybe 12 to 2 o'clock for the higher bands when all tuned up. Same (+/-) for the PLATE
control.
At no time should you see Plate?Current pin to the right!? If so...something is wrong.? Mistuned...gain too high...bad output cable or load etc.
Good luck!? Hope I've spelled this out correctly.? Doing it from memory.? Others are welcome to chime in!
73
Peter
VE7PS
73
Peter
VE7PS
OK guys,
?
Here is an observation. I just cleaned the power connection and decided to check the bias again. All knobs turned to ¡°0¡±. Now, on the RF tune I see a ¡°0¡± in the 10 meter section.
At this point I can get the bias to the tick mark. Now I see another ¡°0¡± in the 160 meter range. The lowest bias setting here is .3 amps
?
With the bias set now the tune procedure is closer to what I see on videos and I get a grid dip. But for normal operation all knobs are fully CW.
?
Dean
?
?
Barry...indeed, check for correct idling current with zero
drive. Adjust it using the bias control on the AC-4 power supply.? You are aiming for about 70 mA (the "tick mark").
Also.....practice tuning up into a known good 50 Ohm load rated at 150w or better with known good cables first.?
Dump the "tuner" for now.? I would put a wattmeter inline to the 50 ohm load if you have one,?rather than trying to use the internal relative output meter.? That way there are fewer buttons to "mess" with until you are comfortable with the tune-up process.
And if you are pinning the ammeter...STOP right away, as something is wrong!? Back off the drive and try again.
?
How have you set your bias. That¡¯s the first step. Pinned to the right is not a condition you want to be in for long so I would suggest not tuning up until you figure it out.? I would verify
that you have appropriate and steady bias current first.
On Thursday, January 2, 2025 at 10:01:40 AM CST, Dean N2TNN via
<n2tnn=[email protected]> wrote:
I have a T-4XC in great condition but is not acting normal. It puts out 110 watts, sounds great on CW and cooperates with my straight key. Unknown about
the SSB side because I never used it.
This is difficult to express because I don't really know what I am talking about so here goes. Tuning the rig on different bands takes forever to get
it right. I have watched videos and it looks easy. I follow the instructions in the manual and it never is the same.
All controls are set CCW. I then turn up the gain control slowly, maybe 1/4 the way and the needle pins to the right. Once it is pinned I can never get
it to dip when I adjust the plate knob.
So what I do next is to fool with the controls to get max power out with the lowest SWR on the tuner. With the load knob adjusted for output the needle
is still pinned. When I push it in the needle moves down to about .300
Also, after tuning up with the "tune" setting I go to CW and when I key down I have to fine tune all the settings again.
I really like this rig and want to use it but something is not right. Any suggestions?
|
Re: Sources for T4XC final tubes?
From what I understand, the same is true (tubes are too tall for the RF cage) with some 6GJ5 tubes if you decide to go that route for a set of emergency spares.
- Steve W7SJT
"Always look for a positive solution then Improvise, Adapt, and Overcome" - U.S. Marine Corp
"There are no rules here!...We're trying to accomplish something!!" - Thomas Edison
"Someone may be born with more talent than you, but there is no excuse for them to work harder than you." - Anonymous
You are braver than you believe, stronger than you seem, and smarter than you think!" - Winnie the Pooh
?
On Friday, January 3, 2025 at 12:01:50 PM MST, David via groups.io <david.w5xu@...> wrote:
Please note that all 6JB6 tubes are not the same.? There are several out there that are about 1/2 inch?+ longer than those supplied with the radios.? These will not allow the top of the EF cage to be used.? I am not sure but I think RCA is in that arena.? So, while you consider the available?alternatives, consider how tall they are. David Assaf III W5XU, VP8RXU ?
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
On Friday, January 3, 2025 at 12:20:11 PM EST, Jay W6CJ via <lastradioman= [email protected]> wrote:
Group, I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73, Jay W6CJ
|
I thought this was in reference to Surplus Sales' (COL) SPKR-4-57 on https://www.surplussales.com/Microphones-Audio/MicroAudio-8.html.? Is that incorrect? 73, Barry - N4BUQ
Mark, went to the site, but no speaker comes up with your speaker information.? Wrong part number perhaps?? Joe ¨C W7RKN (Ahhhhhh¡¡just did a search for MS4 speakers¡.sold out!....MS4, RV4, SPR4, C4 5.5 x 10.75 x 12.5 SOLD OUT) From: [email protected] [mailto:[email protected]] On Behalf Of Mark - WB0IQK via groups.io
Subject: Re: [DRAKE-RADIO] Speaker? ? I've been replacing my MS-4 speakers with an exact replacement that Surplus Sales sells.? MS-4 SPEAKER REPLACEMENT ( Misco #JC57CD ) Sold as a Collins Replacement:
Surplus Sales of Nebraska, 1218 Nicholas Street, Omaha, NE 68102, Phone: (402)?
346-4750, Part #: (COL) SPKR-4-57,?
Web:
|
? ? ? ? ? ? ? ? ? ? ? ? ? Mark, went to the site, but no speaker comes up with your speaker information.? Wrong part number perhaps?? ? Joe ¨C W7RKN ? (Ahhhhhh¡¡just did a search for MS4 speakers¡.sold out!.... MS4, RV4, SPR4, C4 5.5 x 10.75 x 12.5 SOLD OUT) ? From: [email protected] [mailto:[email protected]] On Behalf Of Mark - WB0IQK via groups.io
Subject: Re: [DRAKE-RADIO] Speaker? ? I've been replacing my MS-4 speakers with an exact replacement that Surplus Sales sells.? MS-4 SPEAKER REPLACEMENT ( Misco #JC57CD ) Sold as a Collins Replacement:
Surplus Sales of Nebraska, 1218 Nicholas Street, Omaha, NE 68102, Phone: (402)?
346-4750, Part #: (COL) SPKR-4-57,?
Web:
|
Re: Sources for T4XC final tubes?
Please note that all 6JB6 tubes are not the same.? There are several out there that are about 1/2 inch?+ longer than those supplied with the radios.? These will not allow the top of the EF cage to be used.? I am not sure but I think RCA is in that arena.? So, while you consider the available?alternatives, consider how tall they are. David Assaf III W5XU, VP8RXU ?
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
On Friday, January 3, 2025 at 12:20:11 PM EST, Jay W6CJ via <lastradioman= [email protected]> wrote:
Group, I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73, Jay W6CJ
|
Re: Sources for T4XC final tubes?
I have used GE, Sylvania and RCA tubes with no issues with the 2-tube transmitters. RCA may need additional capacitance to neutralise properly in a TR-4(any)
With so many years behind us since these sets came out, final tubes are getting scarce. I don¡¯t insist on ¡°matched¡± pairs anymore and have found that keeping the ones with the same frame structure together is more important for the purposes of neutralising properly.?
You can see the frame structure from above. Some tubes have rounded ends and others are more angled. Easier to see than to describe.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 3, 2025 at 13:28, Dean N2TNN via groups.io < N2tnn@...> wrote:
Jay,
I¡¯m looking to do the same?thing. A matched pair is recommended. There is also a ¡°A¡± flavor tube. Which one is correct.?
Dean
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
Group,
I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73,
Jay
W6CJ
|
Re: Sources for T4XC final tubes?
Jay,
I¡¯m looking to do the same?thing. A matched pair is recommended. There is also a ¡°A¡± flavor tube. Which one is correct.?
Dean
toggle quoted message
Show quoted text
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
Group,
I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73,
Jay
W6CJ
|
Re: T-4XC has a "condition"
Peter,?
Thanks again for the comments. I need to clarify one issue.?
If you look at the RF Tune control knob. Clockwise there is a small 0. Counter clockwise?there i a 0. The instructions to set the bias say to put the pointer on 0. Which 0?
I tried to set the bias both ways. Pointed at the CC 0 I can lower the needle to the tick mark. If I use the CcC 0 I can only lower the current to .300.?
At this point I don¡¯t think it¡¯s the transmitter. I believe the power supply has a bias problem.?
Thoughts?
Dean
toggle quoted message
Show quoted text
Dean....you wrote....
OK guys,
?
Here is an observation. I just cleaned the power connection and decided to check the bias again. All knobs turned to ¡°0¡±. Now, on the RF tune I see a ¡°0¡± in the 10 meter section.
At this point I can get the bias to the tick mark. Now I see another ¡°0¡± in the 160 meter range. The lowest bias setting here is .3 amps
?
With the bias set now the tune procedure is closer to what I see on videos and I get a grid dip. But for normal operation all knobs are fully CW.
?
Dean
Sorry but I am losing you here with some of your statements about the "zero" you are getting at 10m and 160.? What "zero" are you talking about?
Start on 40m. Mode switch in SSB position. Band switch?set on 40m.? Plate Tune about 10 o'clock....Load about 10 o'clock.? RF Tune set at 40m.? RF wattmeter in line on the transmitter
output to a 50 ohm dummy load.? GAIN Control set?AT ZERO - all the way
counter-clockwise!!!!!!
Key up the T-4XC with a microphone?PTT? and no audio.....OR put the Mode switch into TUNE.? ?Adjust?the bias pot on AC-4 power supply to set at 70 ma (the tick mark) on
the T-4XC plate current meter.
If that goes OK, then switch the MODE switch to TUNE and increase the GAIN control until you see the meter rise slightly, then peak that reading with the RF Tune control.?
You should see some output on the wattmeter. Quickly peak the PLATE control for maximum output, which should correspond pretty closely to a dip in the PLATE CURRENT.? Increase the load control from the 10 o'clock position slightly, and increase?GAIN slightly,
then dip the Plate Current again to a minimum with the PLATE control. Increase the GAIN control again and do all that once more.? Keep that process?up until you have about 250-300mA Plate current when the Plate control is dipped and output is at about 120w
or so.? Keep the transmissions?short...allow cooling time if needed...which is likely as a beginner.? This whole process becomes much quicker with practice!
You will find that the LOAD control needs to be at around 10 o'clock?for 80/40m and maybe 12 to 2 o'clock for the higher bands when all tuned up. Same (+/-) for the PLATE
control.
At no time should you see Plate?Current pin to the right!? If so...something is wrong.? Mistuned...gain too high...bad output cable or load etc.
Good luck!? Hope I've spelled this out correctly.? Doing it from memory.? Others are welcome to chime in!
73
Peter
VE7PS
73
Peter
VE7PS
OK guys,
?
Here is an observation. I just cleaned the power connection and decided to check the bias again. All knobs turned to ¡°0¡±. Now, on the RF tune I see a ¡°0¡± in the 10 meter section.
At this point I can get the bias to the tick mark. Now I see another ¡°0¡± in the 160 meter range. The lowest bias setting here is .3 amps
?
With the bias set now the tune procedure is closer to what I see on videos and I get a grid dip. But for normal operation all knobs are fully CW.
?
Dean
?
?
Barry...indeed, check for correct idling current with zero
drive. Adjust it using the bias control on the AC-4 power supply.? You are aiming for about 70 mA (the "tick mark").
Also.....practice tuning up into a known good 50 Ohm load rated at 150w or better with known good cables first.?
Dump the "tuner" for now.? I would put a wattmeter inline to the 50 ohm load if you have one,?rather than trying to use the internal relative output meter.? That way there are fewer buttons to "mess" with until you are comfortable with the tune-up process.
And if you are pinning the ammeter...STOP right away, as something is wrong!? Back off the drive and try again.
?
How have you set your bias. That¡¯s the first step. Pinned to the right is not a condition you want to be in for long so I would suggest not tuning up until you figure it out.? I would verify
that you have appropriate and steady bias current first.
On Thursday, January 2, 2025 at 10:01:40 AM CST, Dean N2TNN via
<n2tnn=[email protected]> wrote:
I have a T-4XC in great condition but is not acting normal. It puts out 110 watts, sounds great on CW and cooperates with my straight key. Unknown about
the SSB side because I never used it.
This is difficult to express because I don't really know what I am talking about so here goes. Tuning the rig on different bands takes forever to get
it right. I have watched videos and it looks easy. I follow the instructions in the manual and it never is the same.
All controls are set CCW. I then turn up the gain control slowly, maybe 1/4 the way and the needle pins to the right. Once it is pinned I can never get
it to dip when I adjust the plate knob.
So what I do next is to fool with the controls to get max power out with the lowest SWR on the tuner. With the load knob adjusted for output the needle
is still pinned. When I push it in the needle moves down to about .300
Also, after tuning up with the "tune" setting I go to CW and when I key down I have to fine tune all the settings again.
I really like this rig and want to use it but something is not right. Any suggestions?
|
Re: Sources for T4XC final tubes?
Sylvania 6JB6 are the preferred finals due in part because of easier neutralization.
Group, I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73, Jay W6CJ
|
Sources for T4XC final tubes?
Group, I'm looking for reliable vendors of tubes for the T4XC.
I understand the final tubes have to be from the same manufacturer, but do they have to be a matched pair?? ?(I don't have a tube checker).
Which tubes are best? Sylvania? GE?
Thanks & 73, Jay W6CJ
|
Yes. The RFG control isn¡¯t nearly as important on most receivers that were purpose-built for SSB ¡ª i.e., with product detectors.?
I¡¯ll sometimes play with the RFG during contests but rarely otherwise.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Fri, Jan 3, 2025 at 11:46, rls19 via groups.io < rls19@...> wrote:
This technique was developed originally for receivers that did not?have product detectors. Envelope detection is much?more sensitive to the ratio of local oscillator level versus signal level,?so the signal level going into the second mixer had to?be kept low enough?for proper demodulation by "riding" the RF gain control.
73, Bob AD3K
I learned this as a new novice from my mentor, since "Elmer" was out of style. ?It helps to reduce the effects of lightning and QRM.
73,
Evan, ?K9SQG
I've seen instruction manuals where you adjust the AF gain to a 'comfortable' level and use the RF gain as a volume knob.?
I learned to operate this way in my early days and, as I understand, it helps keep the RF noise out-of-the-radio!
?
--
TNX-n-73's fer now....
KF6JS - Tony
|
Yeah he "did not mean it" (some good info in there!) If he likes pies, lets not set a fresh one nearby...lol WB0IQK Mark, has the right idea. I too used a dual cone speaker, I wanted to stay away from other types of boxes in order to keep the system unity complete. I was not aware of that one shown by Surplus Sales and instead used a common "bulk" speaker used in factory car stereo installs. I think it was like (embedded link) yet mine is 8 Ohm. When you use some additional power, you can boost/cut to suit, compensate for cabinet issues too. There is just enough room (barely) to use dynamat throughout. Discard the cardboard inside and use more proper hardwood ply version, and go. I used contact adhesive to glue black speaker cloth to the hardwood, so when assembled it looks beautiful through the metal grill.? It takes some fiddling around, yet worth it. It sounds a bit better than my SP-20 for sure, and that one is excellent. Oh, I used a thin layer of open cell foam on the back of the AC4 also which is cut to allow ventilation also. Make no mistake, a stock MS-4 sounds terrible, yet does work.
On Friday, January 3, 2025 at 10:39:54 AM EST, n4buq <n4buq@...> wrote:
Richard,
The next time you "don't mean" to post something like this, please post it anyway!? I found this very interesting.
Barry - N4BUQ
> I must comment on a couple of things: Hi-Fi? speakers have extended
> range both ways. Hiss comes from extended high end but it may indicate
> the speaker is resonant or peaky there. Not so good.
>? ? What you call "acoustic suspension" was a trade name for speakers
> made by Acoustic Research (AR). The idea being that the restoring force
> on the cone is made by compressing the air in the box. The box and
> speaker are a unit and must be used together. It allows very low cone
> resonance to be achieved with a relatively small box. The down side is
> that the efficiency is necessarily low if the response is to be flat.
> Despite being much maligned AR speakers were actually very good, if used
> right, but take a lot of power.
>? ? A ported enclosure or "Bass Reflex" once a trade name of Jensen, is
> another case where the speaker and box are a unit and must match. A
> properly ported enclosure increases the efficiency of a speaker for a
> given minimum frequency response but the enclosure forms something like
> a lumped constant quarter wave matching network to the back of the cone
> and for flat response and and best reduction of low frequency distortion
> must be matched to the speaker. This is more than simply tuning the box
> to the speaker free=air resonance.? While some small ported boxes have
> been made in general a ported enclosure must be fairly large to perform
> well.
>? ? The Acoustic Labrynth, once a trade name for an enclosure patented
> by Stromberg-Carlson, is another form of making a matching network for
> the back of the cone, in this case a damped physical quarter wave
> transmission line. Its performance is similar to a bass-reflex. The are
> complex and therefore have never been as popular as the very simple
> bass-reflex.
>? ? Direct radiator speakers are not very efficient, the limit is the
> acoustic impedance match between the diaphragm and the air. The
> acoustic? load on a speaker, equivalent to the radiation resistance of
> an antenna, varies with frequency. It is something like a Bessel
> function. The important part is that below a mid frequency,
> approximately that with a wavelength of about equal to the circumference
> of the cone, the radiation resistance falls off quite rapidly. To
> increase the low frequency output the cone resonance is raised to act as
> a sort of equalizer. Low frequency response below cone resonance drops
> like a rock. If the low end resonance is made lower the overall
> efficiency must be reduced it the speaker is to have flat response. So
> you are stuck. By using an acoustic impedance matching network one can
> increase the overall efficiency obtainable for some low frequency
> response cut off. This is the function of a bass-reflex or similar
> enclosure. A horn acts like an acoustic transformer, increasing the
> acoustic load over a fairly wide range of frequencies, at the cost of
> size and complexity. The low range extension of the Acoustic Suspension
> method is a matter of obtaining a low cone resonance in a small box but
> does not improve efficiency, rather lowers it for the reasons stated
> above for low frequency range vs efficiency of any closed box enclosure.
> The Acoustic Suspension has an important advantage in that the
> compressiblity of the air in the small box is more linear than the usual
> "spider" and cone surround, which form the resoring foce in conventional
> speakers.
>? ? The damping factor of the amplifier also comes into it especially
> with the bass reflex enclosure, where it becomes a part of the total
> acoustic impedance of the speaker (electrical to mechanical to acoustic
> inpedance transformation which is accomplished by the speaker includes
> the electrical properties of the amplifier).? Most tube communication
> receives have single ended pentode amplifiers with no feedback having
> poor electrical damping. This can result in peaky low end response from
> bass-reflex boxes. Mostly they do better with totally enclosed boxes
> with some internal damping in the form of acoustical absorbent.
>? ? I didn't mean to post another essay, delete it if you like.
>
> On 1/3/2025 6:39 AM, Floyd - K8AC via groups.io wrote:
>> I'd say that it all depends on how you're using the rig.? If your Drake
>> stuff falls into the "Shelf Queen" category, then the stock MS-4 is the
>> way to go.? My C-line is in daily use along with my other vintage gear
>> and the MS-4 is a loser for several reasons: It sounds terrible, it
>> takes up too much space and the fact that most folks house the AC-4 in
>> it restricts where you can place it on the operating desk.? I've found
>> that speakers designed for home theatre or music use are a far better
>> choice as they tend to sound great for communications use, are far
>> smaller and can be had for a fraction of what you'd pay for any speaker
>> offered for amateur radio use.? A few years back, speaker manufacturers
>> were convinced that everyone would be buying surround sound speaker
>> systems for their TV system, and cranked out zillions of "surround sound
>> speakers" to be used at the rear of the listening area.? These tended to
>> be much smaller than the main speakers, but with very good performance.
>> Today those speakers are sitting on shelves in Goodwill and Salvation
>> Army stores at giveaway prices.
>> I have a number of them with Sony and RCA logos on them, obtained from a
>> large "used stuff" store in Winston-Salem, NC.? A couple of them match
>> the Drake gear perfectly and are the right color and size.? Such
>> speakers are typically either ported or acoustic suspension, so have low
>> end response that produces a good sound for SSB.? ?Another good speaker
>> alternative are the ones made for use with a PC.? ?West Mountain Radio
>> makes a pair of powered speakers labeled "COMspkr".? While those are
>> powered speakers, one of the pair just has an RCA speaker connection.
>> I don't believe that wide range or hi-fi speakers are unsuited for
>> amateur radio use.? If you use them and are hearing unwanted hiss, fix
>> the audio source to eliminate it.? I use an old Timewave DSP-59+ between
>> the receivers and speaker to shape the audio to my liking and eliminate
>> power supply hum and high end hiss.? The LogiKit SCAF-1 filter is
>> another good choice for that purpose.
>> 73, Floyd - K8AC
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> SKCC 19998
>
>
>
>
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John W3KHG
David
Jay W6CJ