104/104A

Tue Sep 4 09:47:14 EDT 2001

Dear Fellow Heath-ites:

I just wanted to expand a bit on what Kees said about the SB-104(A). Heath
offered a simple update kit to improve the receiver sensitivity to all
existing SB-104s out there in 1976. This was free. Heath would also send,
from time-to-time, some additional correspondance along with an update of a
few components, etc., to those valued Heath customers who purchased an
SB-104, depending on the series number of the unit they purchased.

The #830-24 modification kit to update your SB-104 to the SB-104A was never
offered for free; you had to purchase it. In later production lots of the
"A"-version, the TX/TF "C" board was shipped factory built and pre-aligned.
The front end board was always shipped factory built, and this was due to
the difficulty in aligning the 8.395 to 8.895MHz bandpass filter AND the
fallout from the discrete diode-ring mixers used in the first and second
mixers.

Finally to those who feel the SB-104(A) was the most difficult to assemble.
Nonsense. Heath made this kit easy as pie. Don't believe me? Open up an
SB-400 or SB-401 and take a comparison look at the two chassis. Although the
SB-104 had more easy circuit boards, the SB-400/401's chassis was much more
difficult to assemble. Let's not get hung up on the HW-5400.....that was
just in a league by itself. Uh oh.

Regards,

Dave Kechkaylo, W8DLK/9

-----Original Message-----
From: Kees & Sandy [mailto:talen at INETPORT.COM]
Sent: Monday, September 03, 2001 10:03 AM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: Fw: 104/104A

I have a list around here somewhere, but the easiest thing to
do is compare the schematics. There was also a list of fixes
on Dale Wentz's, KB9JJA, Heathkit web site which will give you
an idea of 104 problems vs the 104A ( I made a hardcopy of
the fixes and can provide you a copy at cost if you want). The
major differences were a hotter frontend card which was much
easier to tune up on the 104A, improved tuning on some
frequencies which prevented proper operation on certain bands
on the 104, and incorporating MANY design improvement
changes.

Apparently the 104, which was Heathkit's FIRST major ALL Solid
State HF SSB Transceiver, was rushed to production (probably
over the loud objections of Engineering) to make the Christmas
rush and they paid for it later since the 104A upgrade kit was
offered free to 104 purchasers. Heathkit also started providing
several of the cards/sub-assys "prebuilt" to avoid construction
problems. It was quite a complex kit for the avarage builder
and Heath received many of them back as "unable to get it to
work". Also, if you returned your unit for servicing to Heath, for
whatever reason, the more important fixes were generally
installed for free. Check yours to see if there is a service
sticker ....late service dates are good.

All in all, it's a fine little transceiver, will provide you with lots
of education, is a SSB transceiver YOU can still repair, and
it's definitely a part of Heathkit history.

Check out my Radio Homepage for Heathkit SB-104(A)
repair.

73s Kees K5BCQ
Radio Homepage:  http://www.qsl.net/k5bcq/

----- Original Message -----
From: Martin Tippin <w0akg at AEROSURF.NET>
To: <HEATH at LISTSERV.TEMPE.GOV>
Sent: Monday, September 03, 2001 9:24 AM
Subject: 104/104A

Can any body tell me the main difference between the SB 104 and the 104A ?
Thanks guy's.
Martin L Tippin  W0AKG
140  Monarch Lane
Branson,  MO  65616

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