[Boatanchors] Interesting AR-88 Issue

[Sandy]

AR-88 is a truly great "general coverage" receiver.  I much preferred it to 
the Hammerlunds and whatever else came along.
Great piece of gear and very stable considering the "general coverage" 
tuning scheme.

73,

Sandy W5TVW

----- Original Message ----- 
From: "Rodger" <wq9e at dtnspeed.net>
To: <Boatanchors at mailman.qth.net>
Sent: Friday, September 12, 2008 3:50 PM
Subject: [Boatanchors] Interesting AR-88 Issue


> Over the last couple of days I started working on an RCA AR-88 that I
> picked up earlier this summer.  Although it looked fairly good it needed
> cleaning and it was sporting an SX-42 S meter instead of anything close
> to the original RCA look.  Once I started working on it I also found
> several of the "bathtub" caps were leaking oil from their seals so I
> replaced all of them.  Upon power up there was no smoke and good results
> except on the two highest ranges and a quick check showed the HFO wasn't
> working on these two ranges.  A few measurements with the ohmmeter
> indicated an interesting reading because it appeared that a large
> capacitor was slowly being charged on these ranges between the coil
> terminals and ground but the oscillator coils are isolated from the rest
> of the circuit by fairly small capacitors so that made no sense.  The
> tubular trimmer capacitors themselves were the problem.  On the AR-88
> the trimmer capacitors are composed of an aluminum tube with a solid
> aluminum bar inside insulated by a ceramic disc and whatever cleaner or
> lubricant that was used by the previous owner got inside the caps on
> these two ranges and turned them into some sort of home made
> electrolytic cap, when I took them apart I found a white pasty substance
> inside.  I didn't bother to measure the capacitance before cleaning them
> up but fortunately a quick disassembly and cleaning restored them to
> normal operation and now the AR-88 is working properly on all ranges.  I
> checked the other trimmer caps in the oscillator section and they were
> fine so apparently only the two highest range caps were attacked by
> cleaning/lubricant guy.
>
> This ends this breaking news story and now back to your regularly
> scheduled program,  "Upgrade Controversy"  :)
>
> Rodger WQ9E
> _______________________________________________


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