On 10/4/2010 11:24 PM, k7fm wrote:
> This is in response to Eric, wanting to add an amplifier to his Icom 703+.
>
> Eric, there is a major problem. The Icom 703+ is a qrp rig, with an output
> of 5 or 10 watts. The last I heard, amplifiers sold since about 1980 do not
> operate at the 5 - 10 watt level. That is because the chicken banders were
> using those amplifiers to illegally amplify 11 meter signals.
>
> Most of the amps sold since then require 50 to 100 watts of drive.
>
> So, your options are limited. Some military/commercial amps will drive with
> your 5 - 10 watts, but they are rarer than the ham amps and will require
> understand them. Ten-Tec sold a small amp that operated on their argonaut,
> to boost the signal to 50 watts. But, they are quite rare.
>
> The Central Electronics 600L would work ok - but they are not common.
>
> Although this forum is about amplifiers, much of the discussion is bent
> toward the other end of the power spectrum. For this group, 100 - 200 watts
> is qrp.
>
> At the power level , you may be better off building a 5 - 100 watt solid
> state amplifier - but you will have to learn about solid state circuits and
> building.
Of course a good Tetrode or Pentode amp with a tuned input can run the
legal limit with only a couple watts of drive. Unfortunately I don't
know of many circuits or projects already laid out.
Probably most today would build a small amp that would take your couple
of watts and increase them to a level high enough to drive one of the
simple grounded grid circuits.
Another possibility is to find some of the old EF Johnson Thunderbolt
amps, which again are some what rare and might be a bit pricey.
The ARRL Handbook and Classic Amplifier Handbooks would certainly be
worth studying.
Good Luck and 73
Roger (K8RI)
> 73, Colin K7FM
>
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