Update: Further testing in accordance with manual checkout procedures indicates a possible digital board issue unrelated to the previously identified freq drift problem. Before I take the troubleshooting much farther, I'd like to confirm the correct position of the P107 jumper on the digital board. This jumper apparently is used to accommodate differences between the 7-line radios and 5-line radios; the RV75 can be used with either by setting this jumper correctly. I am unable to find definitive info in my documentation on the correct position of this jumper for the TR7. The photo below illustrates how this jumper was set when I received the RV75. Can anyone confirm this is the correct setting for 7-line radios?? Thanks, Rick K8EZB 
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Re: Drake UV-3 transmit offset issue
Ken
that it does. I get the 1.6mHz offset. Never gave it any thought about 220. The one I¡¯m working on does not have the 220 board. However, the offset board might think it does. Good info
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On Feb 7, 2024, at 10:54 AM, Ken, W8EK < KenW8EK@...> wrote:
Hi Mike,
You are getting a 1.6 MHz offset. ?That is
the offset that is normally used on 220 MHz.
Is it possible that somehow (don't ask me how)
that the crazy thing thinks you are on 220 MHz
and gives you that offset?
Just something to check.
Thanks.
73,
Ken, W8EK
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Re: Drake UV-3 transmit offset issue
Hi Mike,
You are getting a 1.6 MHz offset. That is
the offset that is normally used on 220 MHz.
Is it possible that somehow (don't ask me how)
that the crazy thing thinks you are on 220 MHz
and gives you that offset?
Just something to check.
Thanks.
73,
Ken, W8EK
mike bryce wrote on 2/7/2024 10:41 AM:
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Although I promised myself I¡¯d never work on one of these UV3s again¡ I can¡¯t say that anymore
The one I have on my bench has a weird problem with the transmit offset.
I set the dial to the local repeater, 147.18 and of course that¡¯s +600khz. However when you transmit, the offset is 1 mHz.
I¡¯m expecting to see 147.7800 on TX. Instead, I get 148.7800. Switching to -600kHz, I get the same result, 1 mHz lower than it should be
Simplex works as expected.
Simple things out of the way. YES! I did clean the contacts. Yes, I do have the service manual.
This problem is on the offset board. I have several boards and two work, and two don¡¯t. That also means the control head is working correctly (according to the drake manual)
Of course I checked all the diodes on the offset board, and there are quite a few¡
Frankly, I¡¯m baffled by this problem. The service manual doesn¡¯t go into too much detail on how the offset is generated.
Ideas anyone?
Mike wb8vge
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Drake UV-3 transmit offset issue
Although I promised myself I¡¯d never work on one of these UV3s again¡ I can¡¯t say that anymore
The one I have on my bench has a weird problem with the transmit offset.
I set the dial to the local repeater, 147.18 and of course that¡¯s +600khz. However when you transmit, the offset is 1 mHz.
I¡¯m expecting to see 147.7800 on TX. Instead, I get 148.7800. Switching to -600kHz, I get the same result, 1 mHz lower than it should be
Simplex works as expected.
Simple things out of the way. YES! I did clean the contacts. Yes, I do have the service manual.
This problem is on the offset board. I have several boards and two work, and two don¡¯t. That also means the control head is working correctly (according to the drake manual)
Of course I checked all the diodes on the offset board, and there are quite a few¡
Frankly, I¡¯m baffled by this problem. The service manual doesn¡¯t go into too much detail on how the offset is generated.
Ideas anyone?
Mike wb8vge
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I also recently acquired a loaded TR-7. It came with a German version of a VFO stabilizer, and it keeps the TR-7 within 10Hz from dead cold start. Elcon is making the Elcon 34 frequency stabilizer. I used one on an RV-4C and am very happy with the results.
Dale W4OP
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Hi,
New to the forum here.
I've had a C line for some time but recently have got a TR7.
From switch on, there is a gradual slow drift downwards in frequency of both transmit and receive.
During short QSO's this isn't noticeable, but longer QSO's I end up getting comments from the station I'm working.
Over the first hour or so the frequency goes down by approx. 1.6khz, after this it seems to stabilise.
Is this normal for the the TR7, or is it a sign of something not right?
It surprised me that the drift seems greater than my T4XC/R4C line-up
Any thoughts appreciated
73, Dave G0GKH
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Re: Looking for L75 amp meter replacement.
Sounds great, Rob! ?I didn¡¯t change anything with mine other than the scale. Mine said ¡°200uA FS¡± at the bottom of the scale. I didn¡¯t try calibrating it, as it appears to be showing the expected values.?
My amp is an L7, so that may be the difference. You probably don¡¯t need 1A readings at full scale.?
Glad it worked and glad you got one before they were gone!
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 6, 2024 at 22:15, Roberto - YS1RS via groups.io < ys1rs@...> wrote: Have progress to share here.
Received the meter I bought from eBay.
Perfect fit as it was an 83T as the original.
The last one available. It was a 0-300 DC Amp. meter.
Came with an external resistor which I removed but guess what?
The original meter used by Drake for the L75 was 200 uA full scale.
The one received was 1 mA full scale. Tested it with a small circuit I put together and one amperimeter.
Opened it and couldn't find any internal resistor or anything like that inside the transparent meter.
Saw also a few improvements on the movement when compared with the original used on the Drake L75.
Looks like they corrected the issues that made the 83T model, fail on Drakes.
To make things brief...? the internal wire used on the internal meter coil was different than the one used for the 200 uA version.
As expected, all readings were pretty low, when installed it in the L75..
At the end of the day, I had to re-calculate all the meter section resistor network.
After installing the new resistors, went through the meter calibration process shown in the manual.
Have finished replacing all the resistors and now I have a fully functional meter that is a joy to see it working.
Previously, I was adjusting the Amp only by using an external Wattmeter. Actually, the Wattmeter is an Drake MN-2700.
Now, I can read Plate Voltage, Plate and Grid current and it matches what the manual says.
The Relative Output also matches perfectly.
Have written down on my notes the new values installed in case the XYL sells the Amp in the future LOL.
Anyway, wanted to share with you my experience.
Thank you all who helped me finding a solution to my Drake L75 problem.
Learnt a lot in the process.
73
Rob
YS1RS
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Re: Looking for L75 amp meter replacement.
Have progress to share here.
Received the meter I bought from eBay.
Perfect fit as it was an 83T as the original.
The last one available. It was a 0-300 DC Amp. meter.
Came with an external resistor which I removed but guess what?
The original meter used by Drake for the L75 was 200 uA full scale.
The one received was 1 mA full scale. Tested it with a small circuit I put together and one amperimeter.
Opened it and couldn't find any internal resistor or anything like that inside the transparent meter.
Saw also a few improvements on the movement when compared with the original used on the Drake L75.
Looks like they corrected the issues that made the 83T model, fail on Drakes.
To make things brief...? the internal wire used on the internal meter coil was different than the one used for the 200 uA version.
As expected, all readings were pretty low, when installed it in the L75..
At the end of the day, I had to re-calculate all the meter section resistor network.
After installing the new resistors, went through the meter calibration process shown in the manual.
Have finished replacing all the resistors and now I have a fully functional meter that is a joy to see it working.
Previously, I was adjusting the Amp only by using an external Wattmeter. Actually, the Wattmeter is an Drake MN-2700.
Now, I can read Plate Voltage, Plate and Grid current and it matches what the manual says.
The Relative Output also matches perfectly.
Have written down on my notes the new values installed in case the XYL sells the Amp in the future LOL.
Anyway, wanted to share with you my experience.
Thank you all who helped me finding a solution to my Drake L75 problem.
Learnt a lot in the process.
73
Rob
YS1RS
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On Tue, Feb 6, 2024 at 11:26 AM, Jim Shorney wrote:
For slow drift I would suspect a problem with one of the voltage regulators or maybe the master crystal oscillator.
After further review (of the ckt diag and ToO section of the manual, my first guess is voltage regulation of the VCO or VCXO.Basically eveything works, just some slight drift. I'll change over from soldering iron to scope, VOM, and counter and see what I can find. BTW: I emailed Ron, WB4HFM, to see if he could suggest things to look for or perhaps take a look himself and he replied he no longer works on RV75's. So it looks like I am on my own, but with a distant but able assist from the assembled multitude here! Rick K8EZB
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Thanks Tom.
I chose to log in with google.?
73' Sjaak PA3GHL.
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It is starting to sound like this unit suffered from some sort of high voltage event on the control lines. For slow drift I would suspect a problem with one of the voltage regulators or maybe the master crystal oscillator. Rapid drift and no knob control might mean the PLL is unlocked. Don't overlook connector issues. I recently worked on an old Yaesu rig that (among other problems) had an issue where the clarifier (RIT) moved the frequency in what seemed to be a capacitor charge curve rather than following the control as you turned it. The culprit turned out to be corrosion in the VFO connector. Maybe check the RIT switch and associated circuits. And the other switches as well. Mine seem to have a little crud in them as they don't always make on the first push. Someday I will clean them... 73 -Jim NU0C On Tue, 06 Feb 2024 09:03:47 -0800 "Rick K8EZB" <frboswell@...> wrote: Summary: solid progress but more work to do
Details:
? Replaced all electrolytics with new
? Replaced burned resistor R218 150 ohm in ENABLE line
? Replaced damaged axial lead ceramic capacitor C250 .01 mfd bypass +13v to gnd with .01 mfd disc ceramic
Results:
? On power up appeared to work very briefly, then original axial lead ceramic capacitor C251 .01 mfd bypass +13v to gnd began smoking vigorously
? Powered down and replaced C251 with .01 disc ceramic
? Powered up and no new smoke.
? Now works as a VFO as one might expect except that freq does not lock; drifts lower very slowly
Notes:
? I am guessing that the passage of time may have resulted in degradation of the original ceramic bypass capacitors voltage rating.
? Will now go through the manual setup and troubleshooting procedures to identify the failure to lock.
Rick
K8EZB
-- 73 -Jim NU0C
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Thanks Steve.? I have to repair the T4B first. I miss a few tubes and have to clean it and then testing.
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Show quoted text
Op 6 feb. 2024, om 17:08 heeft Steve Wedge, W1ES/4 via < w1es@...> het volgende geschreven:
Use all the cables except for PTO LAMP and CAR OSC. put a shorting plug in the R-4C PTO LAMP jack. Do the transceive alignment per the T-4B/T-4XB but use the trimmer that is used for the carrier oscillator in the R-4C (can¡¯t remember its designator at the moment).?
If you want to do AM, you may need to tweak that trimmer.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 6, 2024 at 10:48, Sjaak van Meurs < Sjaakvanmeurs1@...> wrote: Hello members,
Ik have a Drake T4B and I like to use it with a Drake R4C, how can I connect these at best?
73¡¯ Sjaak, PA3GHL.
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Yeah, that is really strange. Maybe it wasn't really a cap? 73 -Jim NU0C On Tue, 6 Feb 2024 13:24:49 -0500 "John K5MO" <johnk5mo@...> wrote: Good progress! I'm not used to hearing ceramic caps fail. I wonder if
they're subject to metal migration over time as other caps can be. To
shunt enough current to create smoke, it formed a pretty stout short, and
not just a small dendrite.
Thank you for taking the time to document this for us to share in.
John K5MO
On Tue, Feb 6, 2024 at 12:03?PM Rick K8EZB <frboswell@...> wrote:
Summary: solid progress but more work to do
Details:
? Replaced all electrolytics with new
? Replaced burned resistor R218 150 ohm in ENABLE line
? Replaced damaged axial lead ceramic capacitor C250 .01 mfd bypass +13v
to gnd with .01 mfd disc ceramic
Results:
? On power up appeared to work very briefly, then original axial lead
ceramic capacitor C251 .01 mfd bypass +13v to gnd began smoking vigorously
? Powered down and replaced C251 with .01 disc ceramic
? Powered up and no new smoke.
? Now works as a VFO as one might expect except that freq does not lock;
drifts lower very slowly
Notes:
? I am guessing that the passage of time may have resulted in
degradation of the original ceramic bypass capacitors voltage rating.
? Will now go through the manual setup and troubleshooting procedures to
identify the failure to lock.
Rick
K8EZB
-- 73 -Jim NU0C
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Good progress!?? I'm not used to hearing ceramic caps fail.?? I wonder if they're subject to metal migration over time as other caps can be.? To shunt enough current to create smoke, it formed a pretty stout short, and not just a small dendrite.
Thank you for taking the time to document this for us to share in.
John K5MO
On Tue, Feb 6, 2024 at 12:03?PM Rick K8EZB < frboswell@...> wrote: Summary: solid progress but more work to do
Details:
?? Replaced all electrolytics with new
?? Replaced burned resistor R218 150 ohm in ENABLE line
?? Replaced damaged axial lead ceramic capacitor C250 .01 mfd bypass +13v to gnd with .01 mfd disc ceramic
Results:
?? On power up appeared to work very briefly, then original axial lead ceramic capacitor C251 .01 mfd bypass +13v to gnd began smoking vigorously
?? Powered down and replaced C251 with .01 disc ceramic
?? Powered up and no new smoke.
?? Now works as a VFO as one might expect except that freq does not lock; drifts lower very slowly
Notes:
?? I am guessing that the passage of time may have resulted in degradation of the original ceramic bypass capacitors voltage rating.
?? Will now go through the manual setup and troubleshooting procedures to identify the failure to lock.
Rick
K8EZB
?
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Sjaak,
To reset your Groups.io password:
1. Go to?
2. Enter your email address.
3. Click the link below the password field.
73, Tom AG9X
How can I make a new one, or what can I do the best?
PA3GHL, Sjaak.
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Summary: solid progress but more work to do
Details:
?? Replaced all electrolytics with new
?? Replaced burned resistor R218 150 ohm in ENABLE line
?? Replaced damaged axial lead ceramic capacitor C250 .01 mfd bypass +13v to gnd with .01 mfd disc ceramic
Results:
?? On power up appeared to work very briefly, then original axial lead ceramic capacitor C251 .01 mfd bypass +13v to gnd began smoking vigorously
?? Powered down and replaced C251 with .01 disc ceramic
?? Powered up and no new smoke.
?? Now works as a VFO as one might expect except that freq does not lock; drifts lower very slowly
Notes:
?? I am guessing that the passage of time may have resulted in degradation of the original ceramic bypass capacitors voltage rating.
?? Will now go through the manual setup and troubleshooting procedures to identify the failure to lock.
Rick
K8EZB
?
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How can I make a new one, or what can I do the best?
PA3GHL, Sjaak.
|
Use all the cables except for PTO LAMP and CAR OSC. put a shorting plug in the R-4C PTO LAMP jack. Do the transceive alignment per the T-4B/T-4XB but use the trimmer that is used for the carrier oscillator in the R-4C (can¡¯t remember its designator at the moment).?
If you want to do AM, you may need to tweak that trimmer.?
73,
Steve Wedge, W1ES/4
Time flies like an arrow. Fruit flies like a banana.
On Tue, Feb 6, 2024 at 10:48, Sjaak van Meurs < Sjaakvanmeurs1@...> wrote: Hello members,
Ik have a Drake T4B and I like to use it with a Drake R4C, how can I connect these at best?
73¡¯ Sjaak, PA3GHL.
|
Hello members,
Ik have a Drake T4B and I like to use it with a Drake R4C, how can I connect these at best?
73¡¯ Sjaak, PA3GHL.
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Re: Searching for AUX-7 boards¡
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Roberto - YS1RS
Jim Shorney
Joseph K4JNG