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   Home   Help Search  
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Author Topic: TS-520 lost output  (Read 1862 times)
K3WVR
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Posts: 31




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« on: April 08, 2009, 07:45:43 PM »

One day perfect, the next day no output at all. Bias current @60ma. Plate voltage is 800. No ALC indication regardless of driver adjustment and no indication of output in tune. Screen grd voltage switch is up and on. I suspect possibly a relay. How do I check and clean them? What else should I check?
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WB2WIK
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Posts: 21836




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« Reply #1 on: April 08, 2009, 09:26:54 PM »

60mA isn't bias current, it's ZSAC (zero signal anode current) -- it's actually "plate" current, under idling conditions.  If you have 60mA of it, then obviously the tube heaters are on and plate and screen voltages are okay.

If there's no ALC indication and no grid current indication, I doubt it's a relay.  The T-R relay *follows* the PA, and if it's flaky usually you'll have little or no output power, but lots of drive power showing, and normally a lot of plate current (in TUNE or CW with key closed) also -- because power is generated, it just has no place to go so it all gets dissipated in the tubes.

Sounds like you lost drive.  Could be a bad bandswitch contact (try rocking the bandswitch through all the bands several times); could be a bad L.O. crystal, which normally would affect only ONE band and not all of them; could be a bad 12BY7A driver tube; could be lots of things!

WB2WIK/6
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WA3SKN
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Posts: 6973




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« Reply #2 on: April 09, 2009, 05:20:56 AM »

Welcome to tubes!
I would check the driver tube first, the most probable cause.
Good luck!
73s.

-Mike.
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K3WVR
Member

Posts: 31




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« Reply #3 on: April 09, 2009, 12:34:14 PM »

Would the Driver tube just quit from one day to the next? It does still heat up nicely. I will check it and thank-you.
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K3WVR
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Posts: 31




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« Reply #4 on: April 09, 2009, 12:35:20 PM »

Thank you. I will check and clean bandswitch and check driver tube.
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W4DL
Member

Posts: 182




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« Reply #5 on: April 09, 2009, 12:46:55 PM »

Let us know what you find; it's always interesting to know the cause of various problems.

Thanks and good DX!

Mike
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K3WVR
Member

Posts: 31




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« Reply #6 on: April 09, 2009, 02:08:41 PM »

Band switch cleaned and exercised. Still no output on any band. Nxt step is to replace the driver tube.
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KE4DRN
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Posts: 3746




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« Reply #7 on: April 09, 2009, 05:36:27 PM »

hi James,

can you tell us your HV meter reading ?

should be 850-900 volts when in transmit.

if you're reading 400 then your
HV electrolytic caps need to be replaced,
DigiKey p/n P7453-ND  drop in replacements.

http://groups.yahoo.com/group/TS-520_820_530_830/

manuals in pdf here

http://www.n6wk.com/kenwood/

73 james

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KE4DRN
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Posts: 3746




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« Reply #8 on: April 09, 2009, 05:42:01 PM »

hi,

the 9 pin vfo plug at the rear of the radio,
sometimes you get a poor connection and
no vfo signal.

73 james
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WB2WIK
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Posts: 21836




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« Reply #9 on: April 09, 2009, 05:59:00 PM »

>RE: TS-520 lost output  Reply  
by KE4DRN on April 9, 2009  Mail this to a friend!  
hi,

the 9 pin vfo plug at the rear of the radio,
sometimes you get a poor connection and
no vfo signal.

73 james<

GREAT suggestion!  
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K3WVR
Member

Posts: 31




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« Reply #10 on: April 09, 2009, 08:26:03 PM »

HV is between 800 to 850. Difference is between measuring with a VTVM and reading the HV meter on the 520 itself. Seems OK to me.
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K3WVR
Member

Posts: 31




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« Reply #11 on: April 09, 2009, 08:27:58 PM »

I will pull the 9 pin plug and clean and replace. I will advise the outcome of this. I have ordered a new driver tube. I am awaiting it's arrival.
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K3WVR
Member

Posts: 31




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« Reply #12 on: April 10, 2009, 06:20:25 AM »

Late last night after working switches and cleaning pins on rear VFO plug the rig started to respond normally on trans. Unfortunatly is was short lived and now the Rcvr hears only white noise on all bands but 40 mtr. It was receiving find prior to this. There is only some foreign broadcast signals being heard on 40 with minimal s-meter movement. I hear some static and a few birdies on 80. Nothing else. Trans is back to no output. Discouragment is setting in and the reality that I need to find someone in my area with much more experience than I.
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W5GNB
Member

Posts: 428




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« Reply #13 on: April 10, 2009, 07:04:58 AM »

If the driver tube is not defective, check on the under side of the rig on board # X43-1090-002 and take a look at R5 and R6, see that they have not opened up.

These two resistors sometimes fail and produce the symptoms that you have explained.

73's
Gary - W5GNB


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K3WVR
Member

Posts: 31




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« Reply #14 on: April 10, 2009, 10:22:17 AM »

Found problem. It was the tx/rcv relay located on the bottom rear. This affected both tx and rcv. Thanks to all that took the time to help.
73's Jim
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