Topband: preamps homemade ...

[Tom Rauch]

> I'm surprised that none's mentioned the PRE-1 & 2 preamps that K9AY
> builds.  I tested the PRE-2 in my company's lab and found it has an
> excellent IP3 and very good rejection of BC signals.  I don't have the
> numbers in front of me, but I believe they were 50 dB or better.

50dB is a heap of TOI, so the amplifier must have some very beefy
components.

I haven't found an amp with an TOI of 50dB yet, except some post-mixer amps
I built with VHF power FET transistors or high power stud mount CATV
transistors.

For example, I have a homebrew receiver with a VHF flange-mount 28-volt
power FET that has a TOI of 54dB, but it dissipates over 10 watts in the
transistors!

I'm trying to think of a test valid for BCI. My thought is to select a few
frequencies at the upper end of the BCB and a few at the lower that produce
harmonics and IM products that fall on 1800-1900 kHz, and pick the worse
case results.

Does anyone have any suggestions for a test method to fairly compare BCI?

73 Tom