[Collins] 75S-1, more adventures.

[kiyoinc at attglobal.net]

I had a few moments so I opened up the 75S-1.  

Nice job of soldering and good build technique but not
something that jumped out and shouted, "this is how to build a
radio."

What did impress me is the pre-selector mechanism.  Collins
clearly didn't like variable capacitors.  It makes sense to use
inductors because the brass-spring to rotor joint is a weak
point in a capacitor tuned system.  

I didn't see anything that I would call a "black beauty"
although there were some old plastic Sprague caps under the
deck.

I don't know if I'm up to replacing the main power
electrolytic can.  It's tucked up in a tight place near the
rear. I can't imagine unsoldering the wires without melting
insulation. 

It might be cleaner to cut the wires to the old electrolytic
can using diagonal cutters and not attempt to unsolder them
with a 100 watt gun.

When I took the case off, I popped a nut for the rear foot off.
I pressed it back on with a C-clamp.  It's holding.  I thought
I'd have to use superglue.  

The bottom feet have buckled the case in, looks like about a
quarter inch.  Someone must have put a lot of weight on top of
the case.  I used a larger C-clamp on a rubber pad to bend the
case and inner chassis back. It's not quite flat but is no
longer noticeable.

I put the radio back in the case and listened to 40 meters for
a half hour, mostly LSB but some CW. 

The 75S-1 shifts frequency when I flip from SSB to CW.  I don't
like having to retune the signal.

My Heathkit SB-303 keeps the same pitch for USB and CW, which
is nice.  The problem with the Heath is the CW filter is
positioned too far up in the passband. Neither is perfect. 

I see the gearwork on the main tuning dial. I guess that's the
source of the Collins rattle.  My 75S-1 doesn't rattle.