I stopped by Dad's last night and picked up my old radio.
A Zenith 6D512. Like I thought the filters where dry.
the couling and bypass caps checked out perfect. When
Dad's friend re-capped it back then he used "orange drop"
caps. I didn't think they where around that long ago.
We had useable caps in the junk bin, so I fixed it over
lunch, and stayed a extra hour to pull a complete
alignment. The speaker cone has a small crack, that I glued
as a temp fix. But when I fired her up I was able to listen
to the BBC on 5.975. I had forgoten that I added a BFO. Crystal
controled no less. My uncle sent me a "matched" pair of mil
crystals and some house numbered Fairchild transistors, some
perfbord and the other parts. I used a 9V battery, but I think
I can steal power from the cathode in the AF output stage.
I even added a manual RF gain control. Again my uncle gave me
the diagram. He was an Air Force radar tech, who went on to become
a EE. I have ordered "proper" caps, filters and coupling/bypass,
because I don't want to burn up a RF/IF transfomer.
And a bigger shock was the KnightKit Wireless Microphone that
I completly forgoten about. A 12AX7 as a mic and phone amp,
a 50C5 as the RF oscillator/power stage, and a 50C5 as the
AF amp/modulator. I even added a seperte level control for the
phone. You where supossed ton only use a 10' antenna. But I had
much more fun with my ~100' long wire!
My wife says she now understands my interest in cryptography.
After looking at my 40 year old scriblings she says that reading
it is a job best left to the NSA.
But an even bigger shock lay in that old box. I had "air tapes"
of my some of my broadcasts. I took them to work and covertly
dubbed them CD. No way I am going to let my coworkers hear how I
sounded at 14. If I hadn't promised my Mom and wife I would have
bulk earsed then burned the old tapes. I remember that I borrowed
a friends "Norelco" open reel to reel. 7.5IPS. How professional.
It is almost funny. My voice hadn't dropped yet, so I sounded a lot
like my sister.
The Knight kit is going to require a complete overhaul. My Dad was
much smarter then I knew. He made an isolation transformer for the
hot chasies KnightKit from two back to back 120V:24V 4 amp
transformers.
I didn't understand why, all I knew is he threatened to take my toys
away
if he ever found out I was not using the transformers for the KnightKit
or the Zenith. Damn that man sure was smart 40 years ago.
I am planing on restoring the Knight to it's former glory, but I don't
think I will try a 100' antenna. While I don't use my ham license all
that much, I would hate to loose it.
Terry