[Milsurplus] Wanted: BC-610 Tuning Units & Coils

[Robert Kilian]

> Hello, Rob: I don't have any tuning units left here, but I had both an "E" model back in the
> 1960s, and an "I" model later.
>
> I have seen both the TUs and the coils on eBay at irregular intervals.
Definitely watching eBay.   There was a TU for 80 listed several days 
ago, but it was in Italy and the shipping cost was rather steep.   
Mulled over the purchase for a few days and when I went back it was gone.
>
> The "E" model was given to me by AFMARS and was truly a derelict. It was a real mess.
>
> One thing I found is that there is either an RF choke or a resistor (I can't remember which)
> UNDER that phenolic board in the final amp compartment on which the 250TH is mounted.
>
> That was burnt up in my "E" model, apparently from some parasitic which occurs on some
> frequencies.
I'll check that before I apply power. This one sat in a barn and had a 
hefty layer of dust/dirt on every horizontal surface so it's taken lots 
of cleaning to get it into a condition where I believe it's clean enough 
to power up.  Incidentally, I think the dirt acted as a protective layer 
-- the internal surfaces are in pretty good shape.
>
> You might wish to check for that. I found it by accident when I had to change the socket to
> that special one for the 304TL when we could not find any 250THs.
Curious about this conversion. I've read about the challenges of 
conversion away from the 250TH and have heard of successes on that 
front, but  never really came across any details about what the 
successful conversions  entailed.  For now, trying to stockpile 250THs 
and not considering conversion but it would be a good thing to know 
about, just in case.
>
> I and another AFMARS member who had also been given an "E" model by AFMARS
> installed 304TLs and modified our '610s for Class B linear amplifiers and used them very
> effectively for 'phone patching into the SEA area on frequencies above 20 meters.
>
> He drove his with a KWM-2A and I drove mine with a modified Heathkit SB-101.
>
> BTW, the power supplies in both models are very, very robust, but 1) watch for the settings
> of the overload relay. That can be off quite a bit and will cause problems. and 2) you may
> wish to replace the 866 rectifiers with 3B28s, which are far more forgiving of overloads and
> cause far fewer problems than the 866s. Except for the pretty blue glow, I have never liked
> MV rectifiers.
This 610 already has 3B28s installed, but I'll also check out that 
overload relay before powering it up.

Thanks for all of the advice & info!

73 Rob K6RBK
> vy 73 for now,
>
> Ken W7EKB
>
>
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