[AMRadio] Filament choke

John Coleman jc at pctechref.com
Thu Apr 30 10:20:54 EDT 2009

This may be an unwarranted alarm but if it were me, I would increase the value of the RFC in the bias line from 100uh to maybe 1mh.  Your resonate frequency with the .02 bypass capacitor is quite low but I suspect a substantial amount of RF current will still be passing through a 100 uh coil and there may be heating especially if the choke is a tightly wound thing on .25 in form.

Good Luck
John, WA5BXO

-----Original Message-----
From: amradio-bounces at mailman.qth.net [mailto:amradio-bounces at mailman.qth.net] On Behalf Of sbjohnston at aol.com
Sent: Thursday, April 30, 2009 8:37 AM
To: glowbugs at piobaire.mines.uidaho.edu
Cc: amradio at mailman.qth.net
Subject: Re: [AMRadio] Filament choke

Here's my schematic so far for the 160m amp:


This one won't be a as pretty as some... I'm going to build it on a
steel chassis that has been used by others for at least four other
projects and is literally swiss-cheesed with useful holes.  (more holes
than steel maybe)

The front panel is 1/8" aluminum sheet also somewhat holey, but
smoothed and now painted nicely with textured gray.  The cabinet looks
like it came from a later-vintage Meissner Signal Shifter with liftable
lid and plenty of ventilation holes.

Steve WD8DAS

sbjohnston at aol.com
Radio is your best entertainment value.

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