Sunday, October 9, 2011

Heathkit SB-101 makes another QSO!


Heathkit was a significant contributor to the Amateur Radio hobby, their products, in kit form, enabled countless amateurs to explore the hobby in a very important way. Kit building radio equipment was second only to scratch building, but scratch building was a skill that was learned and "progressed towards". The learning's and building enjoyment Heathkit gave us were equaled only by the thrill of operating a radio you could say you understood how it worked.

More information about Heathkit is easily found on the web and you can start at
http://en.wikipedia.org/wiki/Heathkit
http://www.heathkit-museum.com/

Today's radios, are packed full of features in compact spaces, using surface mounted components that are difficult to impossible for the hobbyist to work with in any enjoyable way. Additionally, today's radios are becoming increasingly a product of the software they run and this truly is in the non-enjoyable space.

Even though many Heathkit rigs are more than 40 years old, I think it is easy to understand why these radios are sought after and restored.

SB-101

The SB-101 is a SSB/CW rig manufactured by Heathkit between 1967 to1970. Is is a non solid state (no transistor) tube based radio. The finals are a pair of 6146 tubes and produces about 100 watts PEP output power. The plate voltage in this section in excess of 800 Volts.

SB-101,... at the controls
The controls on the SB-101 are very nice, and when you operate this radio, as with many of this era, you feel engaged and in control. There is something to be said about not "flying by wire".


This radio, that I was able to pick up at a local ham swap meet, was in fine shape. 


SB-101 Inside









The obligatory picture of the innards is to the right. My look inside told me the radio builder paid attention to details and every thing looked in order. The purchase was easy






I did not know it at the time, but I quickly learned that an external supply, the HP-23 is needed to power the radio. Now, I can tell you the sign of a good flea market is one where you can buy a radio on one table and pick up the needed supply at another.
HP-23 Power Supply


I picked up the manual and schematic at http://www.mods.dk/ and started the alignment procedure, the first thing I noticed was the drooping 820V supply. I ordered and installed the HP-23D power supply refurbishment kit from the fine folks at Old Heathkit Parts ( http://www.ultrawebb.com/OHP/index.htm )
 
Below is a picture of the new printed circuit card and components installed in the base of the supply. It replaces all of the electrical parts of the supply except for the mains transformer and choke.
HP-23 Conversion Kit Installed

With this done the 820V supply increased to close to 800V from the 720V previous value. The balance of the alignment was completed and the 40 year old SB-101 easily wallops out a clean 100W on all bands 80M to 10M.

The vintage mic I have is an Astatic "lollipop" D-104 (another flea market item), and once the needed 2pin mic connector was soldered on, and the 9Volt battery was replace, I could see this old radio wanted to get on the air.

Last night I fired out 2 QSO on 40m,...

Amazing! Thanks Heathkit

2 comments:

Hari Sulistiyo said...
This comment has been removed by the author.
Hari Sulistiyo said...

nice vintage transceivers,
73' de yc1rhs.wordpress.com