>
>Quite a succesful weekend working on my TL922...
>
>I replaced the 470uH L2's with a R 27 Ohm and
>a 1000pF C. There is already a 220pF C in place.
>The Zennerdiode ZX 7,5 was replaced by a 6.8 V
>1 watts type and a MJE 3055 (100V 10A) transistor.
>
>The strange effects on the IP meeter turned out to be
>a few blown resistors around the meeter. The 0,68 O.
>was OK, one 1 O was blown and the 1.5 K near the
>IP meeter also. After replacing them the meeter was
>still kind of missreding (might got a hit also) so we had
>adjust a litle with a other R parralel to the 1.5 K.
>
If you do not have glitch diodes across both meters, you are playing
Lotto with the delicate meter movements.
>We tested Voltages first without tubes and later with
>tubes. One test QSO later went well to.
>
>The baby is back online.
>
>Thanks to all the usefull tip's and hints.
>
>I'll do some of Rich's circuit improvements as the
>next step. The heating Voltage measures 5.51
>Volts ... a bit high.
>
? A new world record!. At such a fil V one would receive 4% of the
normal emissive life. .
>I am quite confident that the L2's were blown by
>a shorted tube on a first incident and did not got
>replaced.
? Although it is possible that a shorted tube could cause the +110v
supply to blow a grid choke during standby, some chokes have apparently
been imploded by the burst of grid-current produced by the parasite. //
The best way to tell if you have had a parasitic-oscillation is to
measure the resistance of the resistors // note -- requires unsoldering
one end.// in the vhf parasitic suppressor. If the resistance has
increased more than 50%, my guess is that there is an intermittent vhf
stability problem.
>After replacing the defective tube the
>TL922 had about 20 hours on duty and the secound
>incident happend on standby. We were not able
>to figure out what happend here .... .
>
? Reducing the gain of the 3-500Z/8008s at 120MHz might help.
tnx for update, Helmut. Congrats on new world record!
>____________________________________________
><A>bort, <R>etry or <I>nfluence with larger hammer !
>
>-----Ursprüngliche Nachricht-----
>Von: Helmut (DF7ZS) <df7zs@gmx.net>
>An: AMPS@contesting.com <AMPS@contesting.com>
>Datum: Donnerstag, 24. Februar 2000 13:37
>Betreff: [AMPS] Blow TL922
>
>
>>
>>Hi there.
>>
>>I have a TL922 by Kenwood and the folowing happend to it:
>>
>>On Standby-Mode (after some minutes operation) I heard
>>a loud "bang" . As I looked on the panel the IP-Meter was
>>showing 500mA. Remember the Amp is set to STANDBY
>>not to operate nor the PTT is hit.
>>
>>My guess was maybe a missreading so I pushed the PTT
>>and sended out a short burst via mike. The Power meter
>>showed that the AMP is delivering about 1000 watts as
>>normal. Back to standby - the IP reading is still 500mA.
>>
>>I turned the thing off.
>>
>>Any Ideas what happend ?
>>Anyone had a simular problem in the past ?
>>I am also seeking for a Service Manual to
>>download or faxpoll.
>>
>>Thanks for any help !!!
>>
>>73sss
>>
>> Helmut (DF7ZS)
>>____________________________________________
>><A>bort, <R>etry or <I>nfluence with larger hammer !
>>
>>
>>
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>>
>
>
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>
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