SB401 Problem

[mike bryce]

ron...

I would check the power supply first.

try this...

put the transmitter out of tune. in other words, put the transmitter out of
adjustment and the the finals should draw all kinds of current. i.e. 400 +
ma .. don't key the rig down too long when you do this test.

if they don't check the supply for correct voltage.

if they do draw excessive current in a non resonate state, then look for low
drive from the driver. You may need to peak and tweak the driver coils
between the last transmitter mixer and first driver.

also check the bias voltage it may be out of wack. with the drive control
turned all the way down, key the transmitter. the plate current should be
about 60 ma or so.. i recall the meter has a triangle mark that shows
resting bias on the meter face

but check that supply out first.

Mike Bryce WB8VGE
SunLight Energy Systems

http://www.seslogic.com
http://www.theheathkitshop.com

"Electricity at the speed of light"

> From: The Pollacks <rinkies at CTS.COM>
> Reply-To: The Pollacks <rinkies at CTS.COM>
> Date: Sat, 29 Dec 2001 17:16:49 -0800
> To: HEATH at LISTSERV.TEMPE.GOV
> Subject: SB401 Problem
>
> I am putting my old SB401/303 back on the air after several years of
> storage.  Got the RX going great, but the 401 has some problems:  Mostly,
> the output is very weak (100 ma plate current) and unstable.  I cleaned the
> switch contacts and relay contacts with tuner cleaner, but no help.  Could
> the finals be weak, or ???
>
> Any ideas appreciated.
>
> Thanks
>
> Ron K2RP
> Rinkies at cts.com
>
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