[Heathkit] DX-100B

[Glen Zook]

The DX-100B had only one crystal position that was
switched internally instead of the four crystal
positions that were switched externally.  That is what
one of the slide switches was for.  Also, the chassis
was punched for the kit to add the SB-10 capability. 
Then, there was the difference in the cabinet
configuration.

The DX-100 / DX-100B has a much simpler VFO (not as
exact as a PTO in frequency response and no where as
near stable).  Basically the VFO in the DX-100 /
DX-100B is the same as the VF-1 VFO that was sold for
use with the DX-35 / DX-40 transmitters.

The Maurader is an 80 through 10 meter SSB transmitter
and not a linear amplifier.  The HA-10 Warrior using
four 811 type tubes is the most common of the linears
of the late 1950s and Heath also built the Chippewa
which used, if I remember correctly, 4-400.

It sounds like your DX-100B had the kit installed for
the SB-10 (or possibly a home brew equivalent).  The
VFO in the DX-100 / DX-100B was marginal when used on
SSB in terms of stability.  The VFO in the Apache was
much more stable.

There was also one, or two, capacitor(s) in the
pre-driver that was/were changed in value.  However,
this had little, if anything, to do with any
improvement in operation.

Basically, the DX-100B was not much of an improvement
over the DX-100 (if any).  By the way, those DX-100
transmitters that were converted to use the continuous
loading variable capacitors instead of the fixed
capacitors with a 50 pf variable capacitor (Heath had
a conversion kit availabe for this) were unofficially
called DX-100A units.  That is one of the primary
reasons that Heath came out with the DX-100B as the
later version and not the DX-100A.

Also, Heath had a conversion kit available for both
the DX-100 and DX-100B to add a spotting switch to
activate the VFO without putting the transmitter on
the air.  The instructions for this also included the
modifications necessary to improve the keying
characteristics of the transmitters.

Glen, K9STH


--- David Knepper <cra@floodcity.net> wrote:

Here is what I notice in this B model: Two slide
switches next to the right side of the PTO
 
Three coax fittings - I assume to hook up the SB-10
SSB adapter.
 
Can someone tell me what changes were made when
Heathkit went to the B model.

=====
Glen, K9STH

Web sites

http://home.attbi.com/~k9sth
http://home.attbi.com/~zcomco

__________________________________________________
Do You Yahoo!?
Yahoo! - Official partner of 2002 FIFA World Cup
http://fifaworldcup.yahoo.com