[Collins] In Need Of ..

[Dr. Gerald N. Johnson]

On Tue, 2007-06-12 at 16:45 -0400, Stuart Martin wrote:
> Thank you Jerry for your response.
> 
> I understood that C206 contained PCBs. Glad to know now that was not the
> case.

Pyranol is one of the PCBs. Not, in my opinion, one of the worst of the
PCBs but all PCBs get the same bad treatment. The provable complaint
about Pyranol today is that it never breaks down when released into the
environment which is exactly what makes it a super capacitor dielectric
and transformer coolant. The fact that other PCBs cause great illness
has caused Pyranol to be treated badly. And major users and makers of
Pyranol and its named competitive products have not treated the
environment well, letting large quantities drain into rivers where it is
in the sediment and the water life.

If the capacitor oil has no odor, its not Pyranol. Pyranol has a
distinctive odor and well sealed Pyranol filled capacitors will have
more odor on days with falling pressure as the higher pressure trapped
in the can pushes some through the seals.
> 
> The leaking was contained with in a week or two. I had inspected the unit
> often during the year and nothing appeared abnormal. Running the 30S-1
> during the refurbishing period resulted in no apparent voltage breakdown or
> arcing.

Any failure in that capacitor would only show up as some heat in the
capacitor and more power supply ripple which may not be evident in SSB
transmissions with the PA in linear mode.
> 
> And yes, I am familiar with the 120Hz resonating circuit. The Plastic
> Capacitor specs I received were based on the specs and schematic I submitted
> (7-15kv, I believe). I measured the Q of the combo at 8.9 which I recall is
> specs for the 2800vdc @3% regulation. PC knew exactly where and how their
> cap would be used.

The variation of choke inductance with load current is great enough to
not justify a high tuned circuit Q. When the choke inductance isn't what
the capacitor was tuned to, the major 120 Hz component isn't suppressed
as well as intended. It may be that leaving that capacitor out won't be
very detectable in using the linear on the air. And the capacitor across
the choke increases the higher frequency component in the current fed to
the filter capacitors. There definitely is a trade off and I suspect
increasing the main filter capacitors may be more effective at good
filtering than tuning the filter choke.

> Had I decided to go with that option, They invited me to
> send along the original Collins part for analysis, but because of a medical
> problem with my internal master clock, I was forced to abandon the entire
> project. All that remains is on the CRA Web site in the Album section under
> Summer 2005. The hundreds of photos taken during the power supply and relay
> chassis removal and rebuild were deleted when I realized that hopes of
> completing my book, "Refurbishing the 30S-1, Part-by-Part," came to an end.
> 
> As an 17 year old at Harrison Radio's NY store in '62 where I first use one,
> to the Navy base in northern Germany in '67 when I used my last, hopes faded
> that I would own one. During the years working with Collins gear my favorite
> of all was the 30S-1. It wasn't until my XYL brought one from a local Ham
> did my dream unfold. As she often said, "...You can always be buried in it."
> So like my dreams of running a 30S-1 died, so did my loving wife Molly. She
> passed away May 24th. 
> 
> 73,
> Stu
> 

-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer