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Author Topic: KENWOOD TS-830 NO RF OUT OF FINALS...BUT GOOD IN NEARBY RECEIVER?  (Read 2862 times)
N6QWP
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« on: May 22, 2019, 06:59:00 PM »

Don't have time to get out test equipment before swap meet this weekend.  TS-830 seems fine to final amplifier section: has HV, hear clear audio in nearby receiver, idle current seems ok, no help by switching SG switch and band switch back and forth multiple times.  ALL tubes light up.  When keyed in Tune or CW or Talking into mic on ssb….no Ic, no rf, no alc.....but can still hear in nearby receiver.

Other than a bad SG switch, any quick "trial and error" attempted "fixes" to get output?  I can't believe (other than possibly driver 12AX7 tube being bad), that the finals wouldn't put out some rf.  Hope it isn't something like bad solder joints, caps or something "mysterious".

This rig just came from an estate sale and is going to the swap meet this weekend.  Just wondering if I am missing something simple that is obvious to Kenwood Hybrid users?  It's been decades since I had a TS-520, memory not so great any longer....and I'd love to check out a mistake I'm overlooking to get it online.

No room on work bench, and test equipment put away....have a van full of rigs=no time to get into this radio by the swap meet.  Just looking for something simple that I am missing in trying to get it to work?  Any suggestions?  Would rather pass it on as a working rig....than another project.
« Last Edit: May 22, 2019, 07:21:44 PM by N6QWP » Logged
K4JJL
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« Reply #1 on: May 23, 2019, 05:32:55 AM »

This site may have some quick tips to check it out.

https://www.k4eaa.com/faq.htm

If you have no ALC, it's probably the driver tube (12BY7A, not 12AX7).
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N6QWP
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« Reply #2 on: May 23, 2019, 07:03:22 AM »

Thanx Jared--Good info there.  Appreciate correction on driver tube....no markings left on mine.  Will be looking for one of those elusive "local" tube testers to check it out.

While the tube does light up and get warm, since there is every indication that signals are making it to the driver, and NO rf is coming out of the finals, I guess that is the most suspect of causes....other than possibly no SG voltage.

Any other causes come to mind?
« Last Edit: May 23, 2019, 07:26:46 AM by N6QWP » Logged
K4JJL
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« Reply #3 on: May 23, 2019, 07:50:43 AM »

Maybe check the bias voltage.  I had an old TS-520 that went crazy.  The tube plates would glow orange after keying down for a few secs.
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N6QWP
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« Reply #4 on: May 23, 2019, 08:00:22 AM »

Doubt that...there is NO current AT ALL being drawn in transmit.  It's like the dam is shut....nothing happening at all....but still do have HV.

I am going to have to find a tube tester.  If not the driver tube, then, in ALL probability, it's a SG voltage problem.  Maybe I'll just keep it for a while so I can get to it when I will have more time.  I hate to not give it a fair chance at working. Thanx again.
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N8YX
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« Reply #5 on: May 23, 2019, 08:13:25 AM »

Did you verify that you have screen grid voltage to the PA tube sockets?

On the 830, the SG switch controls a relay on the Rectifier Board. This relay supplies screen grid voltage to the sockets. The board headers are labeled accordingly.

I'd start at the sockets and work my way backwards.
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N6QWP
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« Reply #6 on: May 23, 2019, 08:19:56 AM »

Thanx Fred--I'll do that when I find the time....have to be after the weekend some time.  That will be something to verify is working (will visually try to check and listen for that relay...and get out the meter).

I'll need to find a hard copy of the manual, if I am going to get into fixing it.

It receives well and has two cw filters in it, so worth the effort.  Speaking of worth, while values fluctuate wildly, a realistic value range would start at what price when working correctly?  Anyone sold...or bought one lately?

And....the dumb question of the day:  Other than just when going to use the 830 as a receiver for a period of time, why would one use the SG switch at all?
« Last Edit: May 23, 2019, 08:43:55 AM by N6QWP » Logged
N8YX
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« Reply #7 on: May 23, 2019, 08:47:36 AM »

Speaking of worth, while values fluctuate wildly, a realistic value range would start at what price when working correctly?  Anyone sold...or bought one lately?
I got ahold of a Gold Label version last year for $400. In excellent shape, though one of the CW filters was missing (since located).

I gold ahold of another Gold Label version last year with neither filter installed, a roughish looking cover set and a VFO that has seen better days for $275. It came with a new set of tubes, uninstalled. Since then I managed to find everything I need to turn it into a TS-830M. That is, AM transceive replaces the CW-N Mode selection. I don't care for the way Kenwood implemented the AM transmission function and yet another mod will address that 'shortcoming'.

Similarly, there's a modified TS-530SP in my lineup. To my knowledge it's the only transverter-capable '530 in existence though others may have since duplicated my work - I documented the mod series extensively on another forum. During this exercise, I became intimately familiar with how the two rigs derive and control their PA screen voltage supplies.

A bonus is that all modifications were done with recycled '830 parts. These are fairly common on the surplus market. One can easily turn a '530's Rectifier Board into that of an '830 with minimal component changes.
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N6QWP
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« Reply #8 on: May 23, 2019, 12:45:28 PM »

Found an old Precision Series 620 tube tester in the garage.  Put in tube....reads O on meter when Test button is pushed....but not sure about this test.  I don't like that meter doesn't register at all.

Just found another older cheap tester, EMC model 215.  It reads good....and I think this tester is more reliable.

Sold off my other better tube tester a while ago, so will still have to go out and find another source of a tester to be sure.

I am now tempted to revert back to the SG problem.  That seems more plausible.  

OOPS!!!  

As I was typing, the meter reading dropped waaaay down into the "Replace" side of the meter?Huh

Turned off tester to cool tube and try testing again.  This time meter only went up about halfway into the replace markings.
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My question now is, if the driver tube is "bad"....but NOT DEAD, can this result in ABSOLUTELY NO RF OUTPUT FROM THE FINAL AMP SECTION?Huh?

I would tend to think that the output would be low, but that SOME would still get through?

I guess I still have to have the tube tested in another tester to verify the condition.  Will be looking for another 12BY7 anyway-hope there is one at the swap meet this weekend.



« Last Edit: May 23, 2019, 12:55:44 PM by N6QWP » Logged
N1CX
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« Reply #9 on: May 23, 2019, 02:15:25 PM »

Did you have the heater switch on for >3 minutes? You will get no rf output if that final doesn't have filaments. You will still hear it locally. The 820 had a jumper on the back also if you didn't have the vfo in place, check this with online manuals and what you have locally. Just pointing out some obvious stuff.
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N6QWP
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« Reply #10 on: May 23, 2019, 02:52:47 PM »

Thanx Scott--The heaters were definitely on for a while.  The VFO was fully engaged and operable.  

I am back to either the tube, or lack of SG voltage.

When I have time to turn over the rig where I can work on it....and get out the meter, I will take readings on the finals to see if there is voltage on the screens.  Right now there is not room where it is to gain access for troubleshooting.
« Last Edit: May 23, 2019, 02:55:33 PM by N6QWP » Logged
N8YX
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« Reply #11 on: May 23, 2019, 02:53:31 PM »

The 820 had a jumper on the back also if you didn't have the vfo in place
The x30 series rigs have a self-jumpering Remote VFO connector.
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K4JJL
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« Reply #12 on: May 24, 2019, 05:25:59 AM »

And....the dumb question of the day:  Other than just when going to use the 830 as a receiver for a period of time, why would one use the SG switch at all?

IIRC, and it has been probably 20 years, I think you turn off the screen voltage when neutralizing the PA tubes.  You can turn off the heater switch when RX only, since the RX portion of the radio is solid state.
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N6QWP
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« Reply #13 on: May 24, 2019, 07:23:25 AM »

Thanx Jared.  I thought it was redundant for receive.  It's been that long since I had a Hybrid, also.  

I'm looking forward to acquiring another 12BY7...just to play with one of these rigs again.

I'm hoping that the ham swap meet scheduled for this weekend won't be rained out, I was counting on it as a source to find one.  Unfortunately, it's looking like the weather will not cooperate.  Will probably have to resort to online shopping.

Anyone have any thoughts about a bad driver tube keeping ALL rf output from making it out of the rf amp section?Huh?  ZERO output, alc, and Ic when rig is in transmit and keyed?  

It does have idle current until keyed.

OR...is this more indicative of no SG voltage?Huh?
« Last Edit: May 24, 2019, 07:45:15 AM by N6QWP » Logged
N6QWP
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« Reply #14 on: May 25, 2019, 12:17:59 PM »

I just found a few moments and turned the radio on its side so I could get some voltage measurements.  The SG relay is working.

On the finals, in receive (with no driver tube in its socket), I get -106 on pin 3 on both.  I also get 273 on pin 5 on both.

While I think that the SG voltage is high(?), this makes me believe, once again, that my problem is in the 12BY7 driver tube.

Anyone care to confirm or comment?  Thanx

Weather forecast for the swap tomorrow is rain....so I probably won't be able to find a replacement until I can order one online.  I am anxious to get the tube and confirm that the radio is working again.  Thanx for riding along as I work this out.
« Last Edit: May 25, 2019, 12:35:20 PM by N6QWP » Logged
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