>
>re: parasitic construction.
>-
>Hi Bill,
>-
>I also had problems one of the first times I tried to
>construct and install one of Rich's parasitic kits in
>a floor console model Henry. The resistors got
>really hot and failed.
/\ What mode and which band were you using at the time of R-supp
failure, Skipp?
tnx
>The problem also surfaced on a very cranky SB
>220, I was working through from years of neglect.
>-
>So I did the proper math home work to figure out
>the coil inductance values for my suppressors which
>were right in line with Rich's paperwork. My math
>and testing came up with inductance values about
>85 to 95% of the suppressor kit values.
>-
>Upon construction of my own model suppressors,
>I noticed that very small changes in the physical
>construction added or subtracted from the inductance
>values. Indeed, it's very possible to construct two
>almost exact physical size inductors that differ in
>inductance value a dramatic amount. To much
>inductance is really bad news in a suppressor made
>with low wattage resistors.
>-
>To complete the amplifiers I constructed a batch
>of coils with similar inductance values and ran them
>through my test equipment (HP Network Analyzer
>and a Sencor LC-102) to match up and tweak
>the coils.
>-
>Rich's paper work mentions the resistors do/should
>run warm/hot in operation. Using his values, parts
>and information they do indeed run hot at the high
>end of the HF bands. The tweak is the guy who
>doesn't have lab test equipment to ensure the
>suppressor inductance value is not a significant
>amount over the desired value, else they have a
>potential to fail in certain longer duty cycle conditions.
>-
>My fix was to actually "upgrade" the suppressor resistance
>value to a higher watt rating and use close measured
>and matched coils, being careful to er on the side of
>slightly less than the desired inductance.
>-
>My results then and to this day have been dramatic,
>not one of the many cranky amplifiers I've reworked
>has shown parasitic probablems since my retrofits.
>That includes my very cranky BTI 3-1000 amplifier
>with a really squirly aged tube.
>-
>Rather than argue over any of this, I'll just throw out
>that I prefer to use higher watt MF resistors than the kit
>supplied values and I pay very careful attention to
>the inductance values. In my examples, slightly less
>L might not be enough (for the most part it often is),
>and too much L is almost always bad for the resistors
>when things are running full tilt.
>-
>Your results may vary.. my results are still on the air.
>-
>cheers
>skipp wv6f
>nospam4me@juno.com
>http://sonic.ucdavis.edu I've added all three of the
>vhf arcos amps and some tube data sheets.
>-
>-
>[snip]
>--------- Forwarded message ----------
>From: "bill thomas" <k1xt@hotmail.com>
>To: amps@contesting.com
To: <amps@contesting.com>
>Date: Thu, 19 Jul 2001 13:44:41 -0500
>Subject: [AMPS] Re: Parasitics
>Message-ID: <LAW2-F1202HxYHLBQhE00000f77@hotmail.com>
>
>
>I once had a Henry 2K-3 in which I installed Mr. Measures' suppressor
>kit.
>I thought I was doing a good thing. The first time I put it on 15 meters
>
>several of the resistors exploded much as a shotgun shell would do. I
>promptly went back to the Henry factory suppressors and never had another
>
>problem, nor did I have a problem prior to that. For some stupid reason
>I
>was convinced that that bit of nichrome was going to save me from eminent
>
>disaster. In my 25 years of hamming, never have I experienced a
>parasitic
>with my Henry 2K-3 (2x3-500z's), My AL1200 (3cx1200A7), or my Henry 3K
>Classic X (8877).
>
>This suppressor kit thing reminds me of the travelling salesman selling
>cure
>all elixir out of the back of his wagon. "Guaranteed to cure your gold
>sputtered meatballs...."
>
>Bill Thomas k1xt
>
>_________________________________________________________________
>Get your FREE download of MSN Explorer at
>http://explorer.msn.com/intl.asp
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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