>Hi Dan,
>-
>The W6SAI Handbook, the Heathkit Warrior, the
>Collins 30L-1, various ARRL Handbooks and
>QST Mags through the past decades.
>-
>Of course a few of the above mentioned can be
>found on the http://sonic.ucdavis.edu Amateur
>Radio Page.
>-
>I've seen a few of the other amps replies... my
>only other "two cents" are to comment on
>statements made in the Ameritron Mag Ads
>about mounting 811a tubes horizontal.
>-
>There is a recommended axis for horizontal
>811a mounting.
>-
>But the Ameritron Ad states/hints horizontal
>mounting is bad news. At first glance, grid
>sag damage might make sense...
? The problem is not grid-sag, it is filament sag when the filament is
hot. The W-shaped filament sags no matter how it is oriented, but when
the W is vertical, the filament-to-grid spacing is not affected, so there
is no problem.
>but I've
>never heard or seen of an example of an
>811a sag failure.
>-
>Furthermore, I trust the former Collins
>Engineer(s) who designed and sent the
>30L-1 design through to production. My 30
>plus year aged 30L-1 has never had a bit
>of trouble... still 100% original although I do
>slow start the unit for the sake of the filter
>caps.
>-
>I also believe neutralization is not required
>for a typical 811a layout.
? In g-g configuration, the only place where neutralization is needed is
above the grid-resonance freq. However, there is nothing in Eimac's
"Care and Feeding..." on how to achieve this. The Gonset 201 and the
Heath Warrior 811A amplifiers tried to neutralize their g-g 811A
amplifiers, but both gained a reputation for oscillation. Heath never
again produced a "neutralized" g-g amplifier. The first Ameritron
811amplifier that I saw managed to "pop" and shatter the filaments in its
811As while it was being operated by someone who I consider to be a
knowledgeable operator. A post-mortem investigation with a dip-meter
showed a sharp anode resonance dip at c. 95MHz.
>-
>cheers
>skipp
>-
>[snip]
>--------- Forwarded message ----------
>From: "Dan Evans K9ZF" <danlevans@msn.com>
>Hi Folks,
>Can anyone point out any good 811a amp designs on the web, or elsewhere?
>I'm considering building an 811 based amp for a "beginner-amp-builder"
>project. Basically, I'm just looking for something fairly simple, and
>cheap, I can build and learn from. Besides, I probably have most of the
>parts I need in the old junk box.
>I am aware of a couple of designs on the ARRL's web site, but the newest
>one
>there I've found is 40 years old, there is bound to be some newer designs
>out there:-)
>And please, no flames from the anti-CB crowd. I have absolutely no
>interest
>in 11 meters, or any illegal operations.
>Thanks,
>Dan
- R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
www.vcnet.com/measures.
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