[Kenwood] Kenwood Digest, Vol 116, Issue 11

[John tf]

Bill ,
Let me see if I can help , at least a little ?
With having the spec.s of that amp , the voltages sound close , with the
tubes amps have a high voltage keying , with similar amps about 110 volts
as I remember .
   In your 2nd paragraph with amp disconnected , are you using the keying
relay still [ not mentioned either way ] ?
And are you still having the pop , having the receiver = Rx  on , but not
connected ?
If you are getting the amp to pop , without the Rx connected and hearing
the pop in the Rx , I suspect the Rx is just picking up RF noise and not
taking a voltage surge in the wiring between , the keyer , depending on the
type should separate the Rx from the amp , and best if the keyer is using
an optical switching device .
Back to the amp , if it is popping into the Rx through RF noise , then turn
off Rx listen closely to the amp [ to hear if you can hear arcing of a open
/ shorted device ] ?
If you can hear , this is dangerous so proceed with " caution "   !!!!
Pull the case off , if there is a safety interlock - close the switch , and
look to see if you can see the arc , from some distance , you may need to
operate amp on its side in order to see most of the components , if you can
not see or hear while doing this , you may want to turn the lights off so
that the arc can show itself easier .
If non of that works , its a matter of checking components with test
equipment .
   I would suspect caps 1st .
And maybe someone else will direct you straight to the issue :)

John
KD0CAC


On Mon, Dec 30, 2013 at 11:00 AM, <kenwood-request at mailman.qth.net> wrote:

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> Today's Topics:
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>    1. TL922A noise (Bill Riches)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 29 Dec 2013 20:45:16 -0500
> From: "Bill Riches" <bill.riches at verizon.net>
> To: <kenwood at mailman.qth.net>
> Subject: [Kenwood] TL922A noise
> Message-ID: <002a01cf0500$cac54ae0$604fe0a0$@riches at verizon.net>
> Content-Type: text/plain;       charset="US-ASCII"
>
> I am using a TL922 an Icom 7600 and I am keying the amp via a keying relay.
> A noise problem just showed up.  When amp is keyed or unkeyed a loud pop is
> heard in the receiver.  It hits 20/9 on the s meter.  Amp is working ok -
> 1kw with 100 watts input. Idle current is 175 ma.
>
>
>
> I disconnected the transceiver from the amp and hooked up the Tek 465 so
> see
> what is coming from the amp input to the 7600.  I see 6 volts ac when keyed
> and I also see a 75 volt pulse when the amp is keyed and then it is
> unkeyed.
> I haven't taken the bottom off of the unit to check out bias relay and the
> bias diode D2 and the 100 mf cap C26 across the diode.  I am going to check
> that out tomorrow.  The amp was bought new in 1986 with the same finals and
> no problems.  When I purchased the amp I put an hour meter on it and only
> have about 1000 hours on the tubes. I don't want to use the amp until this
> problem is resolved as the 7600 does not like strange pulses coming back at
> it!
>
>
>
> Any ideas on what this problem could be?
>
>
>
> 73,
>
>
>
> Bill, WA2DVU
>
> Cape May, NJ
>
>
>
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> End of Kenwood Digest, Vol 116, Issue 11
> ****************************************
>