I bought this approximately 25 year old
40/20M QRP rig at a hamfest for
$25 and thought I got a good deal until I noticed it had a "rattle"
inside.
Upon opening it up I found the receive mixer board floating inside the
chassis with it's wires cut. The book I got with it was a photocopy of
a photocopy so reconstrucing the rig was largely a process of
elimination.
When I fired it up the VFO didn't work, it's transistor was bad and
there
were a number of grounding and stability issues to deal with. Once the
VFO started up the transmitter came up okay with 1.8W out but the RX
sensitivity was horrible, about 300uV. The mixer FET was either bad, or
an incorrect substitution as it's number didn't match the one on the
schematic.
The one called for I couldn't find, and dual-gate FETs are hard to come
by
these days. I put in the only one I could find, an RCA 40603 from Dan's Small Parts . This brought
the sensitivity up to about 10uV which while nothing to write
home about, is a whole lot better than 300uV. Upon having a QSO with
my friend WB5QYT on 40M CW I officially declared this radio fixed. I
don't plan on using this radio, rather I'll keep it around as a
showpiece
of what radios were like in the "olden days"- drifty, microphonic and
bulky!
