[Milsurplus] FRR-59 Adventures

[Bruce Gentry]

    I found an FRR-59 about a month ago and began restoration. Thanks to 
parts from others on this group, the lower sideband decoder is now 
working and the 100 KC digit counter is replaced.   I made careful notes 
of the positions of everything with the old counter turned all the way 
counterclockwise, set the replacement the same way and installed it.   
Powered it up, and thought everything was going great. The continuous 
tuning calibration was surprisingly close.  Next, I tried the 500 cycle 
incremental tuning. It worked...for about 10 minutes and quit. It was 
too late to continue so I left it for this morning. I turned it on, and 
the incremental tuning worked great. I quickly switched it off, got a 
note pad and my scope ready, then turned it on and sampled the 
waveforms  in the blocking oscillator stage. As I had expected would 
happen, it quit working- and the waveforms coming out of the blocking 
oscillator were totally whacko. Then I noticed the B+ on the stage was 
jumping by about 20 volts. A check showed the entire 160 volt buss was 
going bonkers. That turned out to be the filter condensor sockets were 
loose. The negative terminals of the condensors were connected to the 
shield rings on the sockets. With the anodized aluminum chassis and 
loose screws, the condensors had a very poor ground. I wired the 
negative pins of the sockets directly  to the negative side of the 
rectifier, remounted the sockets tightly, and the B+ jitters are gone. 
Then, of course, the incremental tuning quit working. The waveform 
coming out of the blocking oscillator was pure hash. The primary of the 
transformer was reading about 200K ohms and going all over the place. 
For grins and giggles, I found a couple small cup cores and made a 
transformer. It works great!  I  left the receiver on to cook all night  
and it is still working fine this morning, the incremental tuning is 
still fine.   If it is still working after a few days, I will tackle the 
alignment of the front end. The lowest band is off by 100KC so the 
harmonic amplifier is misaligned. Even so, the sensitivety and 
selectivety are great. I am going to make a guess  the epoxy 
encapsulation on the pulse transformer corroded the winding or tore a 
connection loose.  I  may drop it into a jar of acetone and see if the 
encapsualation dissolves, see how it failed, and see how far off from 
the original my homebrew transformer is. I am still looking for the 
connection "blister" panel for the back of the converter section cabinet 
and the studs or buttons that secure it. It would be nice to be able to 
put it in the cabinet rather than having the wiring jury rigged on the 
bench.   The saga continues, and is a good warmup for a Russian  R-155 
that is on it's way to me :)

      Keep the soldering irons hot and the suds cold!

       Bruce Gentry KA2IVY