I would like to add one more: Florida RF laboratories.
They make power resistors for high frequency uses, including two terminal
types. They're really intended for use on a heatsink, but at reduced power
they can handle what appears in a suppressor. At least, you can be sure with
them you won't have inductance problems. I didn't check the price on the low
power models.
In any case, a 20W model should handle , without heatsink, whatever a
suppressor can hand to it.
Alex 4Z5KS
-----Original Message-----
From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
Behalf Of mikea
Sent: Thursday, September 03, 2009 6:38 PM
To: 'Amplifier Reflector'
Subject: Re: [Amps] Carbon Resistor Substitution
On Thu, Sep 03, 2009 at 05:51:05PM +0300, alexeban wrote:
> You have to be careful!
> The film resistors are formed by cutting a spiral groove in the metal film
> to lengthen the path and obtain higher resistance. It looks something akin
> to a wire wound resistor actually.
> I think Vishay has a family of non inductive resistors, especially made
for
> RF work but I can't remember the power ratings.
> Alex 4Z5KS
>From the May-July 2007 Mouser catalog:
Vishay/Sfernice thick film power resistors page 527
LTO 30 and LTO 50: 30 and 50 watt TO-220 package
LTO 100: 100 watt TO-247 package
Affordable
Ohmite TAP series heat-sinkable low inductance and capacitance page 526
TAP 600: 600 watts, air or liquid-cooled heatsink
TAP 1000: 1000 watts, requires a liquid-cooled heatsink
Very Pricey
ARCOL thin and thick film non-inductive power resistors page 516
FPA series: 100 and 250 watt
Somewhat pricey
Caddock MP series non-inductive power resistors Page 517
15, 16, 18, 20, 25, 30, 36, 60, and 100 watt
TO-126, -220, and -247 packages
Affordable
Caddock MP725 series non-inductive power resistors, page 518
25W, "D-pack" package.
Affordable
All look interesting. If I had to make a high-power dummy load, I'd look
at putting a number of LTO-100 in series-parallel.
--
Mike Andrews, W5EGO
mikea@mikea.ath.cx
Tired old sysadmin
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