> I am pretty sure that the choke is a National R175A. It has several pie
> sections on it. I think it is 145 micro henries. One catalogue says 225
> but a couple of reference say 145.
The 175A is not a pi-wound choke.
Describe yours a little further, and I'll run it down for you in the National
catalog. I expect you have an R-152 or R-154.
The R-175A should not have resonances in the 160-80-40-20-15-10 meter
bands unless it sits in an unusual environment in the amp.
Most of the old National chokes will not work on some WARC bands, or
some even on 30 meters.
Over the years, construction articles using the R-175A choke had the
builder removing turns due to layout and other resonance problems.
If one of these is picked up used, it is a good idea to see if the form
is full of wire to assure the old factory specs.
(((73)))
Phil, K5PC
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