From: "Lee Bahr" 
Subject: Fw: [drakelist] KA1FAN diode question


73   Bob, KC8YY
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In my estimation, replacing 45 year old electrolytics and poor =
quality=20
paper caps that are 45 years old is not doing shotgun or unreasonable=20
restoration. On the contrary, it is the prudent way.  You are =
not=20
being stupid, lazy, or ignorant.  You are being wise and =
smart.  In=20
fact you have engaged in a lot of extra work up front.  I have =
found very=20
few paper caps that old that don't leak.  Plus electrolytic =
manufacturers=20
back then never designed their caps to last this long.  A leaky cap =
can=20
introduce hum and if and when it shorts, it can take out a lot of =
components=20
hard to come by today. (Look at a government issue R-390A=20
receiver.  It's power supply electrolytics were plug in)! =
 I=20
would rather take preventative measures and use modern fresh and better =
made=20
components to protect my radio and the parts in it which are becoming =
ever so=20
more scarce.  Maybe sometimes you can repair a radio without doing =
the=20
above, but you sure have not restored it and you probably have set in =
motion a=20
ticking time bomb.  Just have your bias supply fail by taking =
the=20
cheap route and see what you think needed to be replaced as a =
precautionary=20
measure once you have the failure.  We are taking about 45 year old =

equipment here.  You don't order parts from the factory anymore for =
these=20
radios.  They are not 5 years old. We are not working,
"on the =

clock",  and trying to figure out how to keep the repair =
charges down=20
to $100 by putting in only $2.00 worth of parts into a repair that takes =
5=20
minutes to accomplish.   Protect your radio by
replacing=20
problematic parts before you have a catastrophic failure.  These =
radios are=20
already taking a pounding by having 123 volts pumped into their =
primaries rather=20
then the designed 110 volts of yester year.  Todays caps are made =
much=20
better, have MUCH better tolerence, are smaller and cost very =
little. =20
Diodes are made better with closer tolerances and of greater current =
capacity=20
and give me much peace of mind knowing at least these parts won't let me =

down.  Even installing a relay circuit to switch on power from the =
small=20
on-off switch thus taking the load off the switch makes sence =
today. =20
Try and find a new switch when this puppy fails!  While we are =
at it,=20
don't forget to replace all the out of tolerance resistors too!  =
(Sometimes=20
with a modern higher wattage unit of equal size).
 
I just had my auto's timing belt replaced at 60,000 miles per the =
mfg=20
maintenance schedule.  The price was $400 but that was much cheaper =
then it=20
would cost me to rebuild my engine if the old belt failed and  I =
neglected=20
to replace it as specified in my manual.  Just think what the =
manufacturer=20
would have in the manual if they knew I would be driving this car 45 =
years later=20
to keep it running reliably!  To each his own, but the chief =
engineer at=20
radio station w0vt plans to keep on taking preventative measures with =
this=20
station's vintage equipment.  If you don't head this advice and =
your radio=20
blows up, let me know, I'd be happy to buy your radio as a parts radio =

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