SB102/R202

[Steve and Anne Ray]

R-202 in the SB-102 is different then R-202 in a HW-101.  Why Heath did this
I do not know.  Anyway R-202 in a HW-101 goes from the top of T-102 to pin 2
of V5a.   Where in a SB-102 the resistor labeled R-202 goes from pin 7 of
the V5a to ground.  Removing R-202 from a SB-102 and replacing it with a
wire will eliminate the grid bias on V5a.   You need to put R-202 from V5a
pin 7 back in.

Furthermore there is no resistor in the SB-102 that goes from T102 to pin 2
of the V5a.   So that problem has been solved in the SB-102.  Apparently
Heath played with this resistor in the HW-100/101 and SB-100 series rigs.
Basically if a resistor goes from T-102 to pin 2 of V5a replace it with a
piece of wire.   Sorry for the confusion my article on KB9JJA page may have
caused.

The most important trick in troubleshooting a HW/SB101 etc. type of rig is
to use a VTVM to check the voltages, and check the rf voltages with a rf
probe and a VTVM or scope.  Quite often one will find a 10K resistor that
has gone up in value, especially in the audio stages giving low audio
output.  I have seen several rigs with this problem. Apparently Heath had
some problems from whoever they purchased the resistors from.   I remember
one SB-102 I worked on where the receiver worked fine, but the transmitter
output was low and the problem was in the power supply for the LMO, I cannot
remember which, but either R941 or R939 had changed value.  This resulted in
to low a voltage to the LMO, giving to low output in transmit, but plenty
for receive.
73,

Steve Ray K4JPN ex K1VKW HW-101, HW-8, SWL 30-40,
Pixie II, NC 38S, OHR 100A 30 M and Heath Kit fan
Warner Robins, Georgia

-----Original Message-----
From: Ray A. Allen, Sr. <w2kbr at TOAD.NET>
Date: Friday, February 26, 1999 7:19 PM
Subject: SB102/R202


>Group:
>        Still tble shooting this SB102 for low output, and inconsistant
>readings vs the book...
>
>In any case readin thru notes, I see on 2 occasions, fellow Heath guys/
>gals strongly recommend removal of R202, replace with plain wire
>to increase drive....Assume transmit drive since R202 is pin 7
>of V5...in any case gave it a shot, and Drive and output fell thru
>the floor...like NADA very very low output, MIC/CW pot wide open full CW
>and nada...Now did I do something wrong...or has the removal of R202
>made a bad situation..... worse...  I wonder......
>
>Any thoughts greatly appreciated.. es 73 Ray
>--
>******************************
>Ray A. Allen, Sr., W2KBR/3
>8303 Grainfield Rd.,
>Severn, Maryland, 21144-2331
>******************************
>

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