HW100 CXR NULL POT

[Kenneth G. Gordon]

On 22 Feb 2010 at 10:05, Dick KF4NS wrote:

> I recall someone mentioning a while back that a replacement would be a 
> 10 turn 200 ohm pot from Mouser or Newark. After a thorough search of 
> both catalogs, I cannot find such a pot with the same dimensions as 
> the original.

There isn't one. Mr. Goncalves is correct. Use a Bournes 10-turn job. Works 
just fine.

> Nothing had the terminals pointing up in parallel with 
> the adjusting shaft.

You would NOT want to mount it that way anyway!!! The metal case of the 
original pot had to be insulated from the circuit board in order to not short out 
something there. Not a good idea at all, IMHO. I have repeatedly found the 
necessary insulator missing.

Besides, then one had to solder a wire to the metal body and ground it. 
Soldering to the metal body of the original pot can damage the resistance 
element. Again, not the best idea.

> Should I be looking for one with entirely different dimensions and 
> jury rig it to fit?

No jury rig: just poke the legs down through the holes from the top and solder 
on the bottom as you would with any other standard component.

> 
> When I get done with the repair I believe I will have cured a 
> miserable problem that seemed to have no solution, which really is 
> killing my ego as a troubleshooter extraordinaire. Will not say yet, 
> but if this fixes things I will tell the tale.

Good. Keep us informed.

I have used the 10-turn pots in my SB/HW all-banders and it makes nulling 
the carrier amazingly easy, unlike with the original, usually damaged, one-
turn job.

I also routinely replace the diodes in the balanced modulator with new 
Schottky's.

Ken Gordon W7EKB

-----------------------------------------------------------
Products bought, sold or traded here is the responsibility of the
parties involved.  This list and the City of Tempe are not responsible
for losses or misrepresentations of any kind.  Buyer beware!

-----------------------------------------------------------
This list is a public service of the City of Tempe, Arizona
-----------------------------------------------------------

Subscription control - http://www.tempe.gov/lists/control.aspx?list=HEATH
To post - HEATH at LISTS.TEMPE.GOV
Archives - http://lists.tempe.gov/archives/HEATH.html