Needed Info: 100-250 Coil, GD-1B

[Dick Blaney]

Your right, that darn thing does fall out of the box, and everytime I
open it, I have to get down on my hands & knees to find it.  Here are
the dimensions taken from my original coil.
It is, in fact, a 1/2 turn loop.  It is made of brass (I think) tin
plated, 0.1875" (3/16") diameter round stock.  Each end is turned down
to 0.120" (~1/8") by 0.300" long.  Center to center of the enda it is
0.715".  End of pins to top of loop, 0.900".   unturned (full
diameter) portion of loop, 0.600".  There is approximately 1/8" of
straight 3/16" section between the end of the reduced diameter pin and
the start of the arc.  Shouldn';t be too much of a problem to make if
someone had a small metal lathe.  Hope this helps, and if you need
more information, feel free to ask.
73 de
Dick, WB8MHE
wb8mhe at bright.net

-----Original Message-----
From: al winfrey <awinfrey at iquest.net>
To: HEATH at LISTSERV.TEMPE.GOV <HEATH at LISTSERV.TEMPE.GOV>
Date: Saturday, June 26, 1999 4:15 PM
Subject: Re: Needed Info: 100-250 Coil, GD-1B


>Hi Steve,
>
>That coil is the one that always falls out when you open the box. If
I remember right ,
>it is just a "hairpin loop" made from 12 or 14 ga wire and having a
length of maybe 3 cm
>or a little over an inch.  It would be nice if someone else having an
actual coil could
>give you the exact measuerments.  You could adjust the calibration by
squeezing the coil
>a bit.  Hope that helps.
>
>Al - wa9hsl
>....
>
>Steve Harrison wrote:
>
>> Howdy,
>>
>> I've obtained a great-condition GD-1B from a very kind fellow in
>> Connecticut; but it is missing the 100-250 MHz coil and manual. I
probably
>> don't need the manual too badly (there isn't much to a GDO, after
all!);
>> but I would like to try to duplicate the original 100-250 MHz coil
if
>> possible. Also, I'm curious about any alignment instructions that
Heath may
>> have had (so the manual might be useful, after all). And, I found
the
>> original 82-ohm cathode resistor shorted with a jumper for some
reason. I
>> want to get this thing halfway calibrated and working on the
100-250 MHz
>> range in particular to give to a good buddy in Maine so he no
longer has
>> reason to complain "I can't tell if it's oscillating, nor where, if
it is!".
>>
>> SO: can anyone describe to me what the original 100-250 MHz coil
looked like?
>>
>> And, can anyone briefly describe any alignment instructions?
>>
>> And, was shorting that cathode resistor some mod to enable more
consistent
>> oscillation across the V/UHF range, or what?
>>
>> Also, what is the claimed value of the two mica DC blocking
capacitors
>> between the tube grid and plate, and the tuning capacitor??
>>
>> Finally... does the 6AF4 tube have to be in especially-good
condition in
>> order that this GDO operates reliably across the entire range? I
recall the
>> 6AF4 was used extensively as the local oscillator in UHF tuners
some 30-40
>> years ago, pre-Nuvistor days. I'm half-tempted to try a FET since I
don't
>> have any 6AF4s left (got lots of acorns for my own Measurements
Corp.  GDO,
>> though!).
>>
>> TNX Much,
>>
>> Steve K0XP
>>
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