Has anyone checked with Palstar(800-773-7931) for load resistors? They build
some really nice loads and may sell parts???Jim K7RDX..
----- Original Message -----
From: "jeremy-ca" <km1h@jeremy.mv.com>
To: "Bruce Lanning" <belanning@verizon.net>; <Amps@contesting.com>
Sent: Sunday, November 11, 2007 11:27 AM
Subject: Re: [Amps] 50 Ohm Loads
> That was Carl who wrote that.
>
> As you may know, the Carborundums are fragile being not much more than
> powdered carbon granules molded and held together by some bonding agent.
>
> I used a Dremel cut-off disc and started grinding shallow slots and
> measuring after each one. The result was almost nil so then I turned the
> slots into pie cut wedges. The wedges kept expanding until I had a decent
> valley removed and 50 Ohms. Smoothed out the shape with a round file and
> vacuumed well. Then the wound and a bit of the surrounding area was
covered
> with a standard 2 part 3M epoxy resin as used for fiberglassing. Since
> acetone is about the only thing that affects cured resin it was good to go
> into the gallon cans and become pseudo Cantennas for phased verticals and
> general shop use.
>
> Since the value has held I suspect but cant prove that the initial
> manufacturing process caused the resistance to drift soon after production
> and finally stabilized. This may be the reason for a wide range of
> tolerances being offered as well as custom ones at rapidly increasing
cost.
>
> For low frequencies a regular wire wound can be used with a capacitor to
> cancel the inductive reactance. Another use for nichrome (;
>
> Carl
> KM1H
>
>
>
>
> ----- Original Message -----
> From: "Bruce Lanning" <belanning@verizon.net>
> To: <Amps@contesting.com>
> Sent: Sunday, November 11, 2007 12:52 PM
> Subject: [Amps] 50 Ohm Loads
>
>
> > Hi, I note with interest what Larry had to say about filling load
> > resisters.
> >
> > "Bring an Ohmmeter or get a guarantee from a mail order seller as the
> > value
> > can change considerably over time. I have a few that were still sealed
> > when
> > purchased 100W ones that measured 68-70 Ohms. A little bit of file work
> > and
> > sealant returned them to 50 Ohms; they have remained at 50 Ohms for over
> > 10
> > years."
> >
> > Larry I also have filed resisters, but please tell us how you treated a
> > carbarundum resister. I for one would be very interested. I have a Bird
> > Load
> > that measures 55.6 Ohms and I would like it to be 50 Ohms.
> >
> > Bruce
> > W1GBS
> >
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> >
>
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