[TenTec] 6N2 observations

[Dr. Gerald N. Johnson]

On Sun, 2006-07-09 at 15:19 -0700, Shawn Upton wrote:
> Besides, wouldn't a preamp be best anyhow on 2m and
> up, to help with NF and coax loss?  It's another part,
> yes; but since no coax is lossless and that also
> impacts noise figure, a preamp might as well be used
> if you're going to invest money into a good antenna,
> good feedline and a good radio.
> 
> Shawn KB1CKT

A preamp at the antenna is ideal, however the performance of the 6N2 is
so far from the state of the art that it may take two preamps. The
problem with a preamp at the antenna is it often has insufficient
selectivity before its gain to protect it from APRS, and ham repeaters
and commercial pagers. Then the intermod in the preamp negates any NF
benefits. Then it takes attention to sequencing and preamp switching so
it gets switched out of the circuit before transmit power reaches the
antenna and that often takes a sequencer circuit between the PTT and the
radio that switches the preamp, then the radio. All this adds complexity
that wouldn't be there if the radio had a 2 dB NF instead of 12 dB.


-- 
73, Jerry, K0CQ,
All content copyright Dr. Gerald N. Johnson, electrical engineer