[Heath] SB 100 and SB 102

[Kenneth G. Gordon]

On 18 Apr 2012 at 19:00, Lou wrote:

> Can someone tell me the specific differences between the SB-100 and
> the SB -102..I don't have the manual for the SB 100....

There are quite a few.

For one thing, and the most obvious, all SB-102s used a solid-state LMO.

There are many differences in other parts of the various circuits. 

The AGC is a bit different, 

the "S" meter circuitry is different (in fact, there are at least three different "S" 
meter circuits in the SB-102s alone) 

there are certain differences in the biasing and screen voltages for several 
stages, 

the HP-23 power supply used with the SB-100 has lower B++ than the later 
power supplies, 

the SB-102 used the 6HS6 instead of the earlier rigs' 6AU6 at the receiver 
RF and 1st mixer (so did the later SB-101s and HW-101s), 

the SB-102 has added oscillator for use with crystal control, 

late SB-101s and all SB-102s were setup with a molex connector and special 
switching for use with either an external LMO (the SB-640), or with 
transverters, 

some SB-101s and SB-102s had glass-epoxy rather than phenolic boards for 
the small circuit boards that contains the parts around the bandswitch, 

if I am not mistaken, the SB-102 came stock with the 400 Hz CW filter 
whereas that was optional with the earlier rigs, 

etc.

I modified my first SB-100 to an SB-101 standard shortly after I got it, but 
that was at least 50 years ago, and I cannot now remember all the changes I 
made at the time.

Perhap Bob G3OOU, or Glenn Zook, can fill us in on more details. Both of 
those folks are experts at those rigs.

Heathkit seems to have had particular trouble with making the "S" meter 
stable. They used several different versions in all their SB/HW allbanders.

Ken W7EKB