On Thu, 01 Oct 1998 10:45:41 EDT nospam4me@juno.com (Skip S Isaham)
writes:
>
>Carl,
>Thanks for the 802 info. When I first started building amplifiers,
>the B&W chokes were the benchmark, as with the bands-witching units
>B&W sold. The values worked but were not always optimum for a lot of
>my
>amplifiers.
>The 90uh plate choke was a standard for my projects until I started to
>realize one choke doesn't cover 160 to 10 complete, on one form.
>I have never seen or heard of an 802 and was interested in the values.
The B&W 800 at 90uh was a homebrewers and commercial standard for many
years Skip, even Alpha used them and it was partly responsible for the
poor 160M performance of the 77 series.
The 801 came along at 200uh to improve 160M but pre-WARC.
They developed the 802 for the Viewstar PT-2500 that they purchased and
became the B&W PT-2500A. It covered 160-10 including WARC but it was IMO
still marginal at 160.
Around 1993 or so B&W didnt like paying for their ceramic form and went
to Delrin. It was OK for average amps but melted with others.
I have used a glass filled Teflon form which can be machined and I was
selling 802 clones but my machinist decided to croak.
>As for winding the, I have a complete machine shop to spin a few up.
>I've just got to choose a proper form material. After reading the
>posts here,
>I don't trust delrin around RF as much as I once did.
>I'd be interested in hearing about builders preferences in coil form
>construction materials.
>
>cheers
>skip may wv6f
Fiberglass works well but is often hard to obtain in small quantities and
is rough on tools.
I have gone back to ceramic for my own needs in the shop and have a 188uh
design that works well on the 9 MF/HF bands. Was lucky enough to pick up
a whole case of 6" by 3/4" forms at Dayton for real short money.
73 Carl KM1H
>nospam4me@juno.com
>
>>>Hello,
>>>Can anyone provide me with the data on the B&W 802 choke?
>>>thank you
>>>skip may wv6f
>>
>>110uh @ 1.2A ICAS Wound on a threaded 9tpi 3/4" diameter form. Not
>>easily to duplicate at
>>home.
>>73 Carl KM1H
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