[Amps] Bird 1KW+ Load Resistor

[Larry]

Keith Schreiber wrote:
> I'm looking for info and leads on purchasing a replacement resistor, for a Bird oil-filled load.  Bird tells me they no longer have parts for, nor support "this obsolete load" which I believe is from the 1960s.  The model number on mine is 888 and is similar to models 6835, 8813, 8832.  The sticker on the front says 1200W continuous - 1500W for 1/2 hour.

I ran into this problem with a model 883 load. The people at Bird were 
actually pretty nasty about giving me any help at all. They claimed they 
didn't support old models and since they were "inexpensive" I should 
just buy a new one. I asked the clown on the phone why I should but 
something from a company that doesn't support their product. No answer.

I got a different guy on the phone, and asked for the dimensions of the 
resistor in the current equivalent model. He wouldn't give me that 
unless I told him why I wanted it. After some discussion, he finally 
admitted that they probably did have a resistor that would physically 
fit but wouldn't sell it to me because the coolant that goes into the 
load is no longer available. The internal dimension were such that the 
return loss would be adversely affected and they didn't want anything 
with a Bird name tag out in the field with less than factory performance.

I wound up repairing the old resistor with some high tech epoxies. The 
coolant was a problem and that started another learning experience.

The only real requirement for the coolant is that it have no "additive" 
that will corrode or disolve the electrical connections inside. 
Transformer oil is good but is usually only available in 55 gallon 
drums. After a lot of web searching and looking at MSDS sheets to see 
what was in the various oils, I would up using "break-in oil" for 
reciprocating aircraft engines. It is almost straight mineral oil and 
has no "bad" additives like regular motor oil. If you can get 10 weight 
great but my local distributer only had 30 weight so that's what went 
in. It's been in that 1KW load for about 8 years now with no problem. I 
have run 3 KW into it for as long as a half hour at a time. It also has 
decent return loss as high as 144 MHz. didn't need it higher than that, 
so never tested it higher.

Good luck,

73, Larry

Larry - W7IUV
DN07dg - central WA
http://w7iuv.com