I built an HF amplifier kit a couple of years ago. The HF Packer amplifier.
It was around $125. All the parts were there and some things have to be
done by the builder that normally are "pre fabbed". Drilling and tapping
holes, placing parts in enclosures accurately.
The amplifier is fairly small and uses two low priced MOS Power FET
transistors. With about 2-3 watts of drive it will produce 35-40 watts of
output. Very nice filtering arrangement on the output, switchable froom
160-10 meters. Has an RF actuated changeover relay system and it is linear
for SSB use. My K1 drives it easily and quite well.
73,
Sandy W5TVW
Google "HF packer" for website and details.
----- Original Message -----
From: "David Wilburn" <[EMAIL PROTECTED]>
To: "Elecraft Reflector" <elecraft@mailman.qth.net>
Sent: Thursday, April 05, 2007 4:57 PM
Subject: Re: [Elecraft] HF amp kits
Just working from memory here, but wasn't there also a limit that the
amateur could only build one such amp a year?
David Wilburn
[EMAIL PROTECTED]
K4DGW
K2 #5982
Jim Wiley wrote:
The 15 db rule applies only to manufactured for sale amplifiers. It does
not apply to amplifiers that an individual ham builds for him or herself,
particularly when a a kit is not involved.. Section 97.317 of the rules,
which is where the 15 db rule appears, applies to the certification of
external RF power amplifiers that a manufacturer offers for sale.
Home-made amplifiers do not require certification. They must still meet
some standards, such as those involving purity of emissions (harmonics,
for example) and of course must not be operated above 1500 watts PEP, but
that's pretty much it.
I am unsure of how the rule applies to kits, but I think they would be
considered a "manufactured product" if all the parts needed to complete
the amplifier are contained, in the kit. If, however, a "kit" contained
only some of the parts, and could not in itself be assembled into a
working amplifier without adding extra parts, then the certification rule
probably would not apply.
It would be perfectly legal for a ham to build a home-brew grid-driven
amplifier that could take the 10 watt signal from his K2 and boost it
to 1500 watts output. Such an amplifier would have (roughly) 22 db of
gain. A pair of 4CX800 tubes could accomplish this, I think. Remember
also that the old Johnson Thunderbolt could be operated in grid-driven
mode, and it had (still has, if you can find one) similar performance,
using a pair of 4-400 tubes.
- Jim, KL7CC
Chris Kantarjiev wrote:
The Linear Amp kits seem to need a fair amount of drive. I've been
idly thinking about a linear that would allow me to drive it with
my barefoot K2 and get 600-800 watts out for CW.
The limit is 15 dB and is still in the requirements despite the recent
loosening of Part 97. That should give something over 400 watts when
driven by a K2. I don't recall whether the "easily- modifiable" rule is
still there, so it may be possible to have an amp with an attenuator on
the front-end (I heard that one of the Tokyo High Power amps does this,
but haven't verified that).
73, Bob N7XY
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