[AMRadio] FT102 and HDVL for 160

W5OMR/Geoff w5omr at satx.rr.com
Tue Oct 4 13:04:03 EDT 2005

VJB wrote:

> On the HDVL for 160, yeah Geoff, I wouldn't have
> thought they existed, either. Is it printed on thejackbar?

indeed it is!  On both the HDVL Tank coil (big, wide-spaced 4-pin HDVL 
type) says "160HDVL" on it.  The Grid coil says "160BVL" on it.

I felt like Santa Clause and the Blue M&M during the Holiday Season when 
I saw 'em at a Hamfest;   "They DO exist!" 

>Often the stuff they used as a spacer
>between the turns has failed, chemically. Combination
>of the heat in an RF tank, and unstable polymers used
>in plastic of the era.

Got a few of those, but the coils that pretty much are self-supporting 
(40m and up) don't have that problem.  The 75m coils, well.. as 
Otis/K5SWK would say "that's a horse of a different corrall".  I've 
tried using a hot glue gun with limited success, but as one might 
expect, the glue got loose enough to let a turn or two go on the ends, 
but never got pliable enough to drip all over the final... even with the 
heat of a pair of 250TH's in close proximity.

>I'd experiment with alternatives before committing a
>nicely-wound coil to a given material. Some E-Pox-E
>(brand name) seems to conduct at RF, or for some
>reason heats up more than it ought to, which itself
>can lead to problems.

What's the name of the epoxy that dries as clear as glass?  I imagine if 
it was applied properly, it could be made to look a lot like the bars 
that are use in B&W Coil-stock.

>I've had two brands of HDVL, Johnson and B&W, and
>neither of their 80 and 40 meter examples did very
>well 50 years after they were made. 

As previously stated, the 40m coil is pretty much self-supporting.  75m 
is a different story, and the 160m coil...  currently resembles a 'limp 

>To repair, I drilled two rectangular pieces of
>plexiglas to a slightly larger hole than the guage of
>wire, and then used high-temperature glue at the
>bottom and top edges, sandwiching the wire turns at
>the correct spacing and holding them in place. The
>plexiglas is cut to the length of the coil form (two
>halves) on either side of the swinging link.
>Hope helpful.

I'm always appreciative of -any- help ;-)

The spacing on the 160m coil -appears- to be somewhat close to that of a 
250 ~ 350pf air-variable cap.  I could take one of those apart, use the 
rotor plates to 'comb' the 160m coil into place, then secure the coil 
with a couple of thin peices of wood or teflon with felt to hold the 
coil in place, while the clear-drying epoxy (that looks like air-dux 
rails) sets up and hardens.  I just hope that the spacing is close enough. 

The wire was, at one time, enamel coated but most of that is now gone, 
too.  Was thinking of taking the coil, after it's been repaired, and 
then dipping it in liquid rubber (like what they make for hand-tool 
grips) as long as the rubber is non-conductive.

I wonder if plain ol' Testors Model glue would do the job, in place of 
the epoxy?  The coil spacing is kinda tight, on 160m...

just thinking out loud, Paul.

73 = Best Regards,

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