[Johnson] Ranger I problem
Jim Brannigan
jbrannig at optonline.net
Thu Aug 31 17:57:39 EDT 2006
Cal, etal....
Preliminary autopsy:
My Ranger choke input HV supply was modified with two 330MF 450VDC filter
capacitors (in series with appropriate dropping resistors)
This was for better power supply regulation.
The plastic insulation on one of the capacitors wore away and the case was
intermittently shorting to ground.
Naturally, this was the capacitor on the top of the string, so 700VDC was
impressed across a 450VDC capacitor. zzzaaaaap!
I don't know if this is the complete solution, but I can't proceed until it
is replaced.
Two capacitors were ordered today.
Thanks for your input....more to come...
Jim
> Sounds like a decoupling problem. I don't know how to
> pin this down but check your bypass caps and
> decoupling caps. I have had a disc ceramic fail in a
> Valiant II. A good hint is the appearance of those
> caps that like they have a fried/bubbly/burnt look.
> FWIW. Cal.
>
> --- Jim Brannigan <jbrannig at optonline.net> wrote:
>
>> More on my adventures with the Ranger.....
>>
>> I isolated the "talking" to the HV choke, this
>> happens only on AM, not CW.
>> Connecting a scope to HV power supply capacitor I
>> get lots of audio on the
>> HV line.
>> The RF was disabled, so this is audio...
>>
>> any ideas?
>>
>> Thanks,
>> Jim
>>
>>
>> >
>> > My Ranger was completely refurbed and has been
>> working properly.
>> >
>> > I put it on the bench to reset the bias and keyer
>> settings, while it was
>> > on
>> > the bench I finished the PTT wiring (ala Phil
>> Salas and WA1HLR).
>> >
>> >
>> > While testing it, I noticed that one 6L6 metal
>> modulator tube was running
>> > considerably hotter than the other (laser
>> thermometer) Substituting glass
>> > 6L6's showed a slight glow on the plates of the
>> tube in the same position.
>> >
>> > Then, in AM, the Ranger started to "talk" to me
>> and I can't quite isolate
>> > the source.
>> >
>> > Resistance and voltage checks are OK. Before I
>> start to take it all
>> > apart,
>> > any ideas??????
>> >
>> > Tnx in advance,
>> >
>> > Jim
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