To: <amps@contesting.com>
> Date: Fri, 15 May 1998 19:10:08 -0500
> I think that's pretty cool! It shows that Rich's supressor idea *DOES*
> indeed work. In a sense you are getting extra resistance out of the
> inductor. And that extra gives you a lower Rp which means lower VHF gain!
Hi Jon,
Can you explain how lower Rp in the suppressor produces less VHF
gain?
If lower Rp means LESS gain, why use a suppressor Jon? What is the Rp
of a dead short?
> Guess those guys in the 1930s who used resistive wire knew a thing or two!
There is a simple reason they used a "shotgun approach" where they
wanted to have lower Q even at the operating frequency.
Back then, tubes were pretty crummy. Even the best state of the
art tubes had VERY long thin leads. External circuits weren't much
better, well shielded enclosures with excellent ground plane
characteristics were virtually unheard of, and some amateur equipment
was simply built on insulated boards.
With circuit layout and components of that era the system needed
high ESR at, and even near, the operating frequency to insure
stability.
It would be my recommendation that anyone using push-pull 304TL's on
a wooden chassis use resistance wire for all element leads, or better
yet insert regular resistors with adequate power dissipation in
series with every lead.
Not only that, the suppressor Rich alludes to was NOT the suppressor
he describes in the kit he sells. It was a clone of an AL-80
suppressor, multi-turn inductor and all. It was not a short hairpin.
I'll certainly be the first to agree that adding series resistance in
the coil path lowers Q and can increase ESR through ALL
frequencies (especially the operating frequency down through dc), but
the bottom line is at VHF it does nothing a small resistance and
turns adjustment doesn't accomplish without all the HF losses.
It isn't the nichrome suppressor won't work, it's just that:
1.) The suppressor tested was NOT the one Rich sells.
2.) Lower Rp is not always a good idea.
73, Tom W8JI
w8ji.tom@MCIONE.com
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