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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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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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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Cleaning/degreasing Chemicals?? ?
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: Drake R4C myseriously dead
With it switched to ON, there¡¯s no need for the shorting plug but you won¡¯t be able to use the calibrator.
Make sure the passband is somewhere within its range and make sure that you have the filter set to SSB to get the widest filter and the most sound. Someone mentioned the NB. Make sure that it¡¯s plugged in or, if there¡¯s no NB, that the jumper plug is in the socket.
73,
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Tue, Jan 28, 2025 at 5:37 PM, Art Delibert via groups.io < radio75a3@...> wrote:
If, as others have suggested, the Mute jumper is in place on the rear, and the noise blanker (or the jumper) is installed, and the tubes are removed and reseated, and it's still dead, I would use another receiver, tuned to the R4C IF frequencies, to see if you can trace the signal and find out where it seems to fail.? Then you would know where to focus your attention.? Easiest to do this if the R4C is tuned to a known strong signal.? (Be careful, of course, not to touch the antenna input of the other receiver to any DC voltage within the R4C.)
-- Art Delibert, KB3FJO
Hello:
I have a Drake R4C that went through the WB4HFN full service option about 5 years ago. It hasn't been hardly used at all.
Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
I find it hard to believe that this happened just by sitting. It was covered with a dust cover the entire time in a temp-controlled room.
Is there something I can try? I tried FUNCTION ON, and every setting imaginable. All tubes are lit (but not tested recently).
I plugged in the long gray cord on the MS4/AS4 combo but got no sound. Neither did I get sound from the front headphones.
Ideas?
Thanks
Scott N1IA
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Re: Comments/experiences sought
On 2025-01-28 14:52, Steve W1SRD via groups.io wrote: If you want a dedicated AWG, the Uni-T UTG962E is small and cost less
than the un-packaged thing on eBay. *** Does it have an attenuator? My Ebay gen has a built-in 72dB one. Yeah, it's a project, but very high quality. Look at the SA trace on the ebay listing. And it's highly accurate, with an OCXO. I have a Hantek scope/DMM/AWG that works up to 25Mhz. I find it endlessly useful, but the gen part is not comparable to this open frame Ebay gen. - Jerry, KF6VB
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Re: Comments/experiences sought
If you want a dedicated AWG, the Uni-T UTG962E is small and cost less than the un-packaged thing on eBay.
73,
Steve
W1SRD
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Re: Comments/experiences sought
On 2025-01-28 13:50, Lyndon VE7TFX wrote: jerry-KF6VB writes:
There's some really neat little stuff out there now. Right here, I have
a project. It's a signal generator I bought from "AF&CH" in Ukraine on=20
Ebay. Jerry, can you post a link to that? I tried a few different
searches but nothing showed up. - Jerry
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Re: Drake R4C myseriously dead
If, as others have suggested, the Mute jumper is in place on the rear, and the noise blanker (or the jumper) is installed, and the tubes are removed and reseated, and it's still dead, I would use another receiver, tuned to the R4C IF frequencies, to see if
you can trace the signal and find out where it seems to fail.? Then you would know where to focus your attention.? Easiest to do this if the R4C is tuned to a known strong signal.? (Be careful, of course, not to touch the antenna input of the other receiver
to any DC voltage within the R4C.)
-- Art Delibert, KB3FJO
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Hello:
I have a Drake R4C that went through the WB4HFN full service option about 5 years ago. It hasn't been hardly used at all.
Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
I find it hard to believe that this happened just by sitting. It was covered with a dust cover the entire time in a temp-controlled room.
Is there something I can try? I tried FUNCTION ON, and every setting imaginable. All tubes are lit (but not tested recently).
I plugged in the long gray cord on the MS4/AS4 combo but got no sound. Neither did I get sound from the front headphones.
Ideas?
Thanks
Scott N1IA
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Re: Comments/experiences sought
jerry-KF6VB writes: There's some really neat little stuff out there now. Right here, I have
a project. It's a signal generator I bought from "AF&CH" in Ukraine on=20
Ebay. Jerry, can you post a link to that? I tried a few different searches but nothing showed up. --lyndon
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Re: Drake R4C myseriously dead
Does the S meter indicate anything? You need a signal source. The internal calibrator will do but the MUTE connector needs to be shorted for it to work.
The usual advice to clean the switches applies. Switch contacts can oxidize just from non-use.
I am much more familiar with the B than the C but think that checking pin voltages might provide a clue.
There are other general suggestions if you can't find anything definite, clean all connectors, tube base pins, etc. Some circuits go to ground through screws, work the screws back and forth a little to make sure they are making contact with the chassis, this will sometimes fix all sots of obscure problem. If you have to signal trace a scope will be of great value.
Also, lift the front panel maybe an inch and drop it, any reaction?
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On 1/28/2025 12:59 PM, Scott N1IA via groups.io wrote: Hello:
I have a Drake R4C that went through the WB4HFN full service option about 5 years ago. It hasn't been hardly used at all.
Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
I find it hard to believe that this happened just by sitting. It was covered with a dust cover the entire time in a temp-controlled room.
Is there something I can try? I tried FUNCTION ON, and every setting imaginable. All tubes are lit (but not tested recently).
I plugged in the long gray cord on the MS4/AS4 combo but got no sound. Neither did I get sound from the front headphones.
Ideas?
Thanks
Scott N1IA
--
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Re: Drake R4C myseriously dead
Oh, if someone pulled the Noise Blanker it will not work.
? ? ?Frank Krozel ? ? ? ? ? ?KG9H Life Member, ARRL ? ? (630) 924-1600 kg9hfrank@...
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On Jan 28, 2025, at 4:06?PM, kg9hfrank@... via groups.io <kg9hfrank@...> wrote:
Are all the jumpers installed?
? ? ?Frank Krozel ? ? ? ? ? ?KG9H Life Member, ARRL ? ? (630) 924-1600 kg9hfrank@...
On Jan 28, 2025, at 4:05?PM, Craig W8CS via groups.io <craig_severson@...> wrote:
I would go for the simple stuff first.?
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Make sure that none of the tubes are loose. Grab each one and re-seat it with a circular motion to make sure that it's centered and no pins are oxidized.?
?
Past that, it's time to check power supply voltages.?
--
Craig/W8CS
Greenville, SC
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Re: Grounding the grids, L7
Flat brass stock has lower inductance than wire. ?But remember that the grids were originally grounded via an RF choke with thin wire.
To ground the grids. Wire or flat strap? I've seen both. What do you guys say?
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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
Isn't there a shorting circuit via an RCA jack on the back panel that has to be considered?
Hello:
I have a Drake R4C that went through the WB4HFN full service option about 5 years ago. It hasn't been hardly used at all.
Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
I find it hard to believe that this happened just by sitting. It was covered with a dust cover the entire time in a temp-controlled room.
Is there something I can try? I tried FUNCTION ON, and every setting imaginable. All tubes are lit (but not tested recently).
I plugged in the long gray cord on the MS4/AS4 combo but got no sound. Neither did I get sound from the front headphones.
Ideas?
Thanks
Scott N1IA
|
Re: Drake R4C myseriously dead
Are all the jumpers installed?
? ? ?Frank Krozel ? ? ? ? ? ?KG9H Life Member, ARRL ? ? (630) 924-1600 kg9hfrank@...
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Show quoted text
On Jan 28, 2025, at 4:05?PM, Craig W8CS via groups.io <craig_severson@...> wrote:
I would go for the simple stuff first.?
?
Make sure that none of the tubes are loose. Grab each one and re-seat it with a circular motion to make sure that it's centered and no pins are oxidized.?
?
Past that, it's time to check power supply voltages.?
--
Craig/W8CS
Greenville, SC
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Re: Drake R4C myseriously dead
I would go for the simple stuff first.?
?
Make sure that none of the tubes are loose. Grab each one and re-seat it with a circular motion to make sure that it's centered and no pins are oxidized.?
?
Past that, it's time to check power supply voltages.?
--
Craig/W8CS
Greenville, SC
|
Drake R4C myseriously dead
Hello:
I have a Drake R4C that went through the WB4HFN full service option about 5 years ago. It hasn't been hardly used at all.
Now when I powered it up on a variac, I get power but no signals, no audio, no nothing.
I find it hard to believe that this happened just by sitting. It was covered with a dust cover the entire time in a temp-controlled room.
Is there something I can try? I tried FUNCTION ON, and every setting imaginable. All tubes are lit (but not tested recently).
I plugged in the long gray cord on the MS4/AS4 combo but got no sound. Neither did I get sound from the front headphones.
Ideas?
Thanks
Scott N1IA
|
Re: Comments/experiences sought
Of course, it does have a few things parked on top of it.?
Steve Wedge, W1ES
Time flies like an arrow. Fruit flies like a banana.
On Mon, Jan 27, 2025 at 23:14, Gordon, KJ6IKT via groups.io < gfsmith@...> wrote:
I feel your pain Steve. My signal generator is a GenRad 1001-A. 50 lbs of pure electrical engineering.
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73, Gordon KJ6IKT
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On Mon, Jan 27, 2025 at 02:00 PM, Steve Wedge, W1ES/4 wrote:
Man, you guys should see my R&S SMPD. 50 lbs of 500 kHz to 2.7 GHz German-spec signal generator! Yeah it takes up 1/3 of my bench. That's the downside...
Steve Wedge, W1ES
Time flies like an arrow.? Fruit flies like a banana.
Sent with Proton Mail secure email.
On Monday, January 27th, 2025 at 3:27 PM, jerry-KF6VB <jerry@...> wrote:
On 2025-01-27 07:07, NU2W via groups.io wrote:
I will stick with the old way---big heavy sig gens, oscilloscope,
muti-meters....
*** Alas I cannot. Limited bench/storage space and bad back. Back in
my salad days, I put in a few years fixing and maintaining big old heavy
test equipment, so there's a bit of nostalgia about that...
There's some really neat little stuff out there now. Right here, I have
a project. It's a signal generator I bought from "AF&CH" in Ukraine on
Ebay. It's
based on an AD9910 Direct Digital Synthesis chip. It generates nice
sine waves using a 900MHz sample clock.
It can also be goosed up to 1.5gHz, but they recommend fan cooling if
you do that.
For HF frequencies, 900MHz is plenty. Spurious are 50dB down. It has a
built in
attenuator - 1 dB steps from 0dBm down to -72dBm.
It wasn't cheap; I bought it fully assembled, with an OCXO ( Oven
Compensated Crystal Oscillator ).
It's got an Arduino card bolted to it; I plan to program that to
implement a signal generator
with a big tuning knob.
- Jerry, KF6VB
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Jim Shorney
Jay W6CJ
Craig W8CS
Scott N1IA