Re: Relative Power on TR-4C
Barry:
D9 on the relay board is likely the culprit, but I'd check D11 and D12, also on the same board,.
The usual cause is a dirty switch though, so make sure it is clean and working properly?first.
And I'd recommend purchasing a TR-4C Service Manual from the K4OAH (now SK) website at .? It makes finding these parts a piece of cake.
73 Peter VE7PS
The relative power function on my TR-4C does not work when I push in the load knob.? The switch seems to be functional.? Plate current meter works correctly.? There's a diode in that circuit that I suspect to be the problem but for the life of me I can't find its physical location so I can test it.? I've traced wires from the switch mounted on the load control shaft back to a PCB that the K1 relay is mounted on.? Found the two resistors there and even swapped the 2ohm resistor which had aged high.? This corrected the inaccurate plate meter.? But there are no diodes on that board that I can see without removing the relay.? Can I get some guidance on where those diodes are located?
?
Thanks,
Barry
KJ5GQM
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Did you verify that Q multiplier is wired for the Drake's IF? ?
On 01/29/2025 9:52 AM EST Paul N5NEN via groups.io <n5nen@...> wrote:
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?
 I have never seen a 2-AQ. But I see how the plug is wired. What I want to do is adapt the wiring of the heath QF1 to the Drake cinch plug. I see where the wires are connected but t want to know what type of coax or multi-wire cable Drake used. ?
? Of course I could just tie the two heath cables to the Drake Plug. I will do that if there is no special cable?
thanks?
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The relative power function on my TR-4C does not work when I push in the load knob.? The switch seems to be functional.? Plate current meter works correctly.? There's a diode in that circuit that I suspect to be the problem but for the life of me I can't find its physical location so I can test it.? I've traced wires from the switch mounted on the load control shaft back to a PCB that the K1 relay is mounted on.? Found the two resistors there and even swapped the 2ohm resistor which had aged high.? This corrected the inaccurate plate meter.? But there are no diodes on that board that I can see without removing the relay.? Can I get some guidance on where those diodes are located?
?
Thanks,
Barry
KJ5GQM
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Re: Cleaning/degreasing Chemicals?? ?
Thanks Steve- I may need to do that. Wish I knew what Ron used to clean my radios....I like the smell of warm tubes but not this cloying smell. ? I'll need to operate the twins from my garage a few weeks more, until the smell subsides. 73 Jay
For the chassis, I use mostly Simple Grewn. Others have reported success with Scrubbing Bubbles but I have found that SB can remove ink on the chassis, so be careful.?
For knobs and the window, I use dish detergent. The meter face gets Windex.?
You need to get in there with parts-cleaning brushes. The kitchen sink or bathtub/shower are good places. Rinse with hot tap water and then post-rinse with about a half gallon of distilled water. I then bring the chassis to the shop and blow out most of the water with about 35 psi air. Into a 120¡ãF oven (higher is okay if yours doesn¡¯t go down that far ¡ª my oven has a ¡°dehydrate¡± setting).? Heat soak in the oven for a few hours.?
Clean tubes with soap and water. If you want to preserve the ink on the tubes, you¡¯ll have to be careful washing them as the ink comes off easily (the tube number etching won¡¯t normally come off).?
I can knock one of these out with a couple hours of work. Of course, the meter, knobs, front panel, crystals are removed prior to washing.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 28, 2025 at 19:41, Jay W6CJ via < lastradioman@...> wrote:
Group,
What degreasing/cleaning chemical brands are used by Ron Baker and other repairers?? ?I did not see a response from Ron after I emailed him with this question.? I'm noticing a sweet chemical scent when I fire up my recently serviced R4C and T4XC.??
Thanks & 73
Jay
W6CJ
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Re: TR4310 HF Transceiver
Well, as Leonard Cohen often said, "Hallelujah!"
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VRTO Digital Board is all fixed and now, every range, whether selected using RANGE (band switch) in conjunction with the up/down buttons, or directly using AUX PROGRAM (Aux-7 board / modules) control, works fine! Seven segment display is all good, including the '2' 10s MHz digit, making its first appearance since I bought this radio late last year:-)
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The two PROM (U32021 & U32018) were thankfully both OK, so I never got to experience the joy of working out their contents and substituting them.
?
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It came as no surprise to find that the muddy deposits that have been a plague on the correct operation of the many functions of this board had affected the logic IC associated with handling the up/down buttons badly. Every IC I changed in this area gave an incremental improvement in functionality. I started with U3028, a monostable that wouldn't, as it's pin 2 timing capacitor input was stuck at half rail (capacitor should charge up to full rail). Then replaced U32026 and U32027, the up/down button flip flops, as they had outputs which were illogical wrt their inputs.
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I was hoping that would suffice but, on test, pressing the up/down buttons many times would cause the range up/down counters (U32024/5) to produce invalid (no-man's land!) outputs, rather than bump nicely against the limits enforced normally by U32021 PROM. So, I replaced both counters.
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Some limits on some ranges now worked correctly, but attempts to select ranges > 20 MHz (using RANGE, or AUX PROGRAM), saw data fed to the Translator Board spinning off into no-man's land again, with the 10s and 1s MHz digits on the seven-segment display blanked, or in some cases showing 1x-type MHz.
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The only remaining logic in the range data chain out to the Translator was U32022/3, not even logic really, just a pair of humble data buffers. Out they came, replaced with Texas CD equivalents of comparatively modern vintage.
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Turning on the radio, I heard a fanfare sound and the room shone gold! I had never seen 21, or 28 MHz previously. What I thought a while back might be a fault with the upper bands VCO, turned out to be nothing of the kind - just the Translator being fed with 'junk' data on the upper ranges.
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Final score for the VRTO Digital Board: Out of a total 28 IC, only 7 remain the original parts that left the Drake factory. Just ludicrous!
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I'm going to do the ALC board mod to improve the talk power, then screw the covers down and enjoy the results. After that, I will move it off the top of the TR7 and get back to finishing that.
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Regards,
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Mark, G4FPH.
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Re: TR-4C Problems with 28.0 and 28.5 bands
I think what you are referring to is the calibrator antenna. It connects to that resistor on one end and goes through the partition and to the band switch. It¡¯s supposed to be open on that end.
On Wednesday, January 29, 2025 at 09:18:59 AM CST, Dave KD5FX via groups.io <land.dave@...> wrote:
UPDATE! I found a white wire not connected to section 4 (starting from the front of the radio). It runs over to a 330K resistor. Picture below. It's the white wire right in the middle of the picture and it runs over to the end of my grey tweeker tool, that's where the 330K resistor is. Can someone with a TR4C check to see where that is supposed to be connected???
Thanks, Dave KD5FX
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Re: TR-4C Problems with 28.0 and 28.5 bands
UPDATE! I found a white wire not connected to section 4 (starting from the front of the radio). It runs over to a 330K resistor. Picture below. It's the white wire right in the middle of the picture and it runs over to the end of my grey tweeker tool, that's where the 330K resistor is. Can someone with a TR4C check to see where that is supposed to be connected???
Thanks, Dave KD5FX
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 I have never seen a 2-AQ. But I see how the plug is wired. What I want to do is adapt the wiring of the heath QF1 to the Drake cinch plug. I see where the wires are connected but t want to know what type of coax or multi-wire cable Drake used. ? ? Of course I could just tie the two heath cables to the Drake Plug. I will do that if there is no special cable?
thanks?
|
The cable of the 2-AQ and 2-BQ is hard-wired in the Q multiplier end.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 28, 2025 at 22:38, Paul N5NEN via groups.io < n5nen@...> wrote:
I am adapting a Heath Q mult to my 2A. I have the cinch plug but I wonder if a special cable was used between the q multiplier snd the receiver. Heath used ?separate cables for the IF and the power , I see from schematics that Drake seems to have used just one? ? ?Any answers? ?Thanks?
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Re: CW with the R4C & T4XC
Yep. An additional benefit of the C Line is that you don¡¯t have to adjust the carrier oscillator on the receiver because they are locked together with the CAR OSC cable. That was a major improvement.?
That beat note is on the low side but I¡¯ve found that I can do the same thing and most ops will take it in stride. I also prefer my note to be around 400-450 Hz bit try and live with a higher one on the Drakes.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 28, 2025 at 19:51, Jay W6CJ via groups.io < lastradioman@...> wrote:
I've been working CW with the R4C and T4XC as 'separates' until now.??
Today, tried something different:? Letting the R4C control both radios.. I found that I can spot the other station at around 550 Hz (haven't measured yet) and we're both dead-on.... no chasing each other up or down the band.? 500-550 may be low for some ears but worked for me.
You OTs already knew this.
73
Jay
W6CJ
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Re: Cleaning/degreasing Chemicals?? ?
For the chassis, I use mostly Simple Grewn. Others have reported success with Scrubbing Bubbles but I have found that SB can remove ink on the chassis, so be careful.?
For knobs and the window, I use dish detergent. The meter face gets Windex.?
You need to get in there with parts-cleaning brushes. The kitchen sink or bathtub/shower are good places. Rinse with hot tap water and then post-rinse with about a half gallon of distilled water. I then bring the chassis to the shop and blow out most of the water with about 35 psi air. Into a 120¡ãF oven (higher is okay if yours doesn¡¯t go down that far ¡ª my oven has a ¡°dehydrate¡± setting). ?Heat soak in the oven for a few hours.?
Clean tubes with soap and water. If you want to preserve the ink on the tubes, you¡¯ll have to be careful washing them as the ink comes off easily (the tube number etching won¡¯t normally come off).?
I can knock one of these out with a couple hours of work. Of course, the meter, knobs, front panel, crystals are removed prior to washing.?
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 28, 2025 at 19:41, Jay W6CJ via groups.io < lastradioman@...> wrote:
Group,
What degreasing/cleaning chemical brands are used by Ron Baker and other repairers?? ?I did not see a response from Ron after I emailed him with this question.? I'm noticing a sweet chemical scent when I fire up my recently serviced R4C and T4XC.??
Thanks & 73
Jay
W6CJ
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Re: Grounding the grids, L7
On my L7 I used copper strap and silver plated it, worked great for me.?
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Show quoted text
On Jan 28, 2025, at 3:09?PM, Roger KW4EMF <rogerlhill@...> wrote:
?
To ground the grids. Wire or flat strap? I've seen both. What do you guys say?
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Re: Drake R4C myseriously dead
If completely?dead, start with the AC cord.? Make sure you are getting an input source?of energy.? Do the tubes light up?? Wiggle them in their sockets.? Regardless of the history?of the radio:? Check that the tubes that are there are in the correct sockets.? You would be surprised here. If you safely can and have power to the radio: Check the power supply voltages.? There are a few of them.? Be careful. Check any and all interconnecting cables between speakers, other radios. READ THE MANUAL.? Place all controls in the expected ranges.??
It is rare that you have nothing going on: at first hand this points to a elementary issue (No AC, No power supply, No tube action).? Once you get action from something (a hum, a hiss, something...) then rotate controls to see if what you here changes.? That MAY indicate that at least the control circuitry that exhibited a change?is at least functional.
Do not be comforted?by thinking the radio worked years ago.? Time changes?things.? Start with the very basics.
Patience and be safe. David Assaf III W5XU, VP8RXU ?
Check all power supply voltages.
On Tue, 28 Jan 2025 12:59:01 -0800
"Scott N1IA via " <soakland5=[email protected]> wrote:
> Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
--
73
-Jim
NU0C
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Re: TR-4C Problems with 28.0 and 28.5 bands
Have you verified that your plate amp meter is accurate? ?If your bias is very low you are going to get some strange behavior from the radio. The meter calibration is determined by a couple of resistors, a 2ohm and a second that is selected during assembly. That 2ohm resistor is critical. At 10% tolerance the max should be 2.2ohms. Mine had aged up to 2.7. ?The other one is a little high too but my meter is way more accurate now. ?These resistors on my TR-4C are on the pcb next to the K1 relay.
You could test the low bias theory by moving your idle current up meter some and see if your 10m output jumps up to something closer to expected output.
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Re: Grounding the grids, L7
On Tue, Jan 28, 2025 at 10:11 PM, Evan wrote:
>Flat brass stock has lower inductance than wire. ?But remember that the grids were originally grounded via an RF choke with thin wire.
The grids were RF grounded with the 3 x grid caps per socket.? ?Grid caps won't pass DC grid current, hence the RF choke on each socket. Stan has done it correctly, using wide copper strap.? ?And do not bond to those machine screws used to recess the sockets below the chassis.? The wide copper strap, being short, has virtually zero inductance.? Save the grid chokes.? They have extremely low DCR, and can be used for other applications.?
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I am adapting a Heath Q mult to my 2A. I have the cinch plug but I wonder if a special cable was used between the q multiplier snd the receiver. Heath used ?separate cables for the IF and the power , I see from schematics that Drake seems to have used just one? ? ?Any answers? ?Thanks?
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Re: Grounding the grids, L7
This is the way I grounded the grids on my L-4B.? Not exactly my
greatest soldering but it's worked for about 10 years...
73
Stan
KM4HQE
On 1/28/25 15:09, Roger KW4EMF wrote:
toggle quoted message
Show quoted text
To ground the grids. Wire or flat strap? I've seen both. What
do you guys say?
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Re: Drake R4C myseriously dead
Check all power supply voltages. On Tue, 28 Jan 2025 12:59:01 -0800 "Scott N1IA via groups.io" <soakland5@...> wrote: Now when I powered it up on a variac, I get power but no signals, no audio, no nothing. -- 73 -Jim NU0C
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Re: TR-4C Problems with 28.0 and 28.5 bands
The loose plate choke connections were obviously not all that bad in terms of electrical resistance or the other bands would not have worked as well as they did.
You have a drive issue, I think.
It was not uncommon for these old radios to present drive drop-off at the higher bands. The radios were designed to account for this by having enough overall gain at the higher frequencies to produce full output. The drive adjust then acted to limit overdrive on the lower bands. Thus, the ability to deliver near full rated power on the low bands becomes less of an indicator of problems unless you need everything full out maximum to get that rated power.
How high up do you need to set the drive level potentiometer to get full output on the lower bands? It should NOT be ¡°full up¡± clockwise! Also, on any given band, the output should level off (saturate) as you increase the drive, and this should occur at something less than fully clockwise. If this saturation phenomenon is not the case, you are lacking drive in earlier stages. If you do get this response, then your low power issue likely lies in the driver stage or final amplifier.
How much plate current do you get on the low bands at full drive vs the high bands? What is your idle plate current with no drive (which should, of course, be invariant over all bands)?
Gary
W0DVN
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Show quoted text
On Jan 28, 2025, at 7:20?PM, Dave KD5FX via groups.io <land.dave@...> wrote:
Latest news on my TR4C. I decided to pull the tubes and test them, when I opened the cage (and shorted out the plate with a screwdriver, power off of course) the plate chokes came loose! TWO OF THEM! Like they were not soldered to the circuit! Ah Ha! That must be the problem! But no, I tested all 3 tubes and they all tested good with the same output value on the tester. No shorts, no grid emissions. So I put them back in and re-soldered the chokes. Turned it on, let it warm up and same result. VERY LITTLE power on 10, like 5 watts or so and about 10 on 15. 20 to 80 is OK.?
So... I'll do ANOTHER check of all the band switch fingers to make sure those are all working and check the various components that get switched in on 15 and 10 meters. Does anyone have a LARGE PRINT SCHEMATIC? The copy I found online is terrible!
73, Dave KD5FX
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Re: TR-4C Problems with 28.0 and 28.5 bands
Latest news on my TR4C. I decided to pull the tubes and test them, when I opened the cage (and shorted out the plate with a screwdriver, power off of course) the plate chokes came loose! TWO OF THEM! Like they were not soldered to the circuit! Ah Ha! That must be the problem! But no, I tested all 3 tubes and they all tested good with the same output value on the tester. No shorts, no grid emissions. So I put them back in and re-soldered the chokes. Turned it on, let it warm up and same result. VERY LITTLE power on 10, like 5 watts or so and about 10 on 15. 20 to 80 is OK.?
So... I'll do ANOTHER check of all the band switch fingers to make sure those are all working and check the various components that get switched in on 15 and 10 meters. Does anyone have a LARGE PRINT SCHEMATIC? The copy I found online is terrible!
73, Dave KD5FX
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Jay W6CJ
Thomas W9TAB
David
Jim Shorney