[Heathkit] refurbishing a HW-101

[k2cby]

I'd be extremely hesitant about pulling components off the pc boards
wholesale.

This is especially true of the coils on the mixer and driver boards. They
are fragile, densely packed, and irreplaceable.

Then there are the boards themselves. They were not exactly mil-spec to
begin with. Too much heat and you are going to delaminate the foil.

What I'd do is:

            Pull the tubes out of their sockets.
Blow the dust off with compressed air.

Take a good look around for charred or bulging resistors and bulging or
leaking capacitors.
Replace any that look suspicious.

Once that's done,
Go to each circuit board and tighten the mounting & grounding screws.
Hit the variable capacitor bearings, the switches and tube sockets with
contact cleaner.
Replace the tubes, connect a speaker and apply power.
Listen to the receiver. If it doesn't work, troubleshoot the receiver
section first.
If - and only if - the receiver works, fire up the transmitter into a dummy
load.

See what works and what doesn't.

The HW-101 specifications are more than a little loose. The rig will work
perfectly fine with parts 10 or even 20% out of whack.

My experience with the HW-101 is that there is quite a bit of RF running
around in small spaces with high impedance circuits.
Do your tune-up with the shields in place and buttoned down. When something
goes awry the first thing I always look for is 
a bad ground - whether on an active component or a shield.

As I recall, the real weak spots of the HW-101 were the carrier nulling
circuit - a cheap pot that had to be replaced - and 
the cage of slug-tuned coils in the mixer plate and IPA driver grid. In the
latter case, I seem to recall stripping the braid off 
a fair amount of RG-174 coax and tacking it down between the vertical pc
boards that hold the coils and the nearest ground.

Good luck.

 

Miles B. Anderson, K2CBY
16 Round Pond Lane
Sag Harbor, NY 11963
Tel.: (631) 725-4400
Fax.: (631) 725-2223
e-mail: k2cby at optonline.net 

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