[Hallicrafters] HT-37 Selenium Rectifier Replacement

[Al Parker]

Hi Bill,
    You were up late last nite.  I saw both of your notes re: this, this
AM.
    You're only at 130-150v coming into the rectifier, so it doesn't need
to be much - I probably have used a 1N4007, 1amp, 1000piv, 'cuz it was
handy, the same as used in the HV secn, and they don't cost much.  For a
dropping rresistor, you just want to drop the extra voltage that is there
due to the silicon vs. selenium rectifier, probably around 20-25 volts,
maybe less.  My notes don't have what I used, but at abt 5ma draw, that'd
need abt a 5k resistor.  There's already an 18k in there which drops abt
80 volts, so I just used ohms law to get the 5ma & 5k for the additional
series resistance.  It's easy enough to give 5k a try.  If you can't get
the bias adjusted to -49v, then try something bigger or smaller.  Or you
might even get to -49v without the 5k --  give it a try.
73,
Al, W8UT

----- Original Message ----- 
From: "Bill Pancake" <bpancake at mindspring.com>
Subject: [Hallicrafters] HT-37 Selenium Rectifier Replacement


Would appreciate a source (and part number) for a modern-day replacement
for the selenium rectifier used in the power supply section of the HT-37
transmitter.  Thanks, Bill, K0JWP