Switch contacts are OK by visual inspection and by ohmmeter.
73, Larry W6NWS
----- Original Message -----
From: "Vic K2VCO" <vic@rakefet.com>
To: <amps@contesting.com>
Sent: Tuesday, November 16, 2010 9:44 PM
Subject: Re: [Amps] Suggestions - I broke my amp - part 2
> Check that the bandswitch contacts haven't burned off.
>
> On 11/16/2010 5:43 PM, Larry wrote:
>> A number of you offered suggestions a couple of weeks ago and I checked
>> those
>> suggestions a couple of times. I have finally got back to trying to track
>> down what
>> is probably a silly error on my part that has broken my Clipperton-L. The
>> mods were
>> triggered by the destruction of the original parasitic suppressors. The
>> amp was
>> working - just not well in all conditions.
>>
>> I replaced the power supply board (just an upgrade to better supply),
>> replaced the
>> plate RFC to an Ameritron AL-572 RFC along with the parasitic suppressor
>> board,
>> changed the plate bypass cap at the power supply side of the plate RFC to
>> a 0.002uf
>> value, changed the plate blocking cap to 0.002uf, changed the filament
>> RFC to a
>> bigger unit, and changed a couple of doorknobs for 160 (unrelated to the
>> original
>> problem of the parasitic suppressors). I haven't gotten to 160 yet. The
>> current effort
>> is using 40. The current result is still no output
>>
>> 1. There is plate current (as measured by the panel meter) and there is
>> plate voltage.
>>
>> 2. I don't have a HV probe but I could measure at the plate voltage (at
>> the plate caps)
>> as the voltage was dropping after turning off the power switch and it
>> tracked with the
>> panel meter.
>>
>> 3. The idle current seems OK.
>>
>> 4. The plate current follows keying. The plate current changes as it
>> should as the driving
>> power is increased or decreased.
>>
>> 5. Adjusting the output cap controls has no noticeable effect on the
>> plate current (no dip
>> etc).
>>
>> 6. Using an ohmmeter there is continuity (short) from the output network
>> side of the plate
>> blocking cap (on the cap lead) to the output connector. From the other
>> side of the
>> plate blocking cap (on the cap lead) to the power supply there is
>> continuity (short).
>> Thinking perhaps the new blocking cap might be bad I replaced it with a
>> pair of 0.001uf
>> in parallel but still have the same result. (I remeasured the shorts
>> after replacing the
>> blocking cap.)
>>
>> 7. The output relay is switching as it should. None of the wiring to the
>> relay was touched
>> in this mod.
>>
>> It has been a long time since I worked on an amp. I am sure I am
>> overlooking something
>> small and silly. I was hoping one of the gurus here might have a pointer
>> or suggestion of
>> something I might have missed.
>>
>> Thanks
>>
>> 73, Larry W6NWS
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>
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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>
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