[BC] Old Farts

[Mark Earle]

jeff at rfproof.com wrote:
> Yesterday a fellow who is going to do contract work for us was inspecting the TX site and planning the job. His son, 11 or 12, was sitting in front of the Continental 816R (he had such excellent taste!) staring in wonder it seemed at the knobs and dancing lights. I began explaining what a transmitter does, and when he continued to be interested I went on. I told him about the exciter generating the FM radio signal and the rest just amplifying that seven watts from the exciter into 19.5 KW exiting the copper pipe at the top. He was even interested in the exciter meter readings, the amps and volts multiplied into watts and the fact that 24 watts in and seven watts out was about 30% efficiency, the rest becoming heat, etc.
>
>   
Last year, my then 20 year old son, EE course of study at UT (KC5SHO) 
assisted me with repairs on an 816R that took a really, really, bad 
lightning strike.

Tubes (all 3), 3 HV rectifiers, 2 scr transformers (in the box no one 
ever services behind the SCR card cage), 3 scr gating cards, 2 scr block 
assemblies.. what else have I forgotten?

We got there at about 3 am, worked through the day with a few breaks, 
had to order parts.. oh yeah, the 2k rectifier for the driver tubes.. 
that came in the next morning, back to work until about 3p. He learned a 
lot, and saw things that only existed as schematics before this. Plus 
for some of it (taking the radio down far enough to get to some of this 
stuff) it was way easier with two persons.

I'm not sure who was more satisfied, when watts started accumulating on 
the meters!

Oh yeah.. after we had it demon-tweaked on the old dud tube (17k out), I 
could not _quite_ get it to tune further. So we shut it down, and took 
the cover off behind the PA cavity to adjust the linkage on the tuning 
servos. We found multiple holes in the harmonic filter and parts of the 
active element melted... so I ajusted the linkage and we backed the 
output down quite a bit.. the filter had to be replaced but that was a 
while later.. the problem was where there were now holes, the metal 
"puddled" and reduced clearance from the active element to ground.. I 
did not want an arc starting.

Expensive hit!

> I think we have a new one coming along!
>
> Jeff.Johnson at rfproof.com,CSRE
> RFPROOF.COM
>   
-- 
mwe

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