Topband: We need better preamps for 160 because FT8 activity

[Jim Brown]

George's work on this system is first class engineering, and has 
revolutionized TopBand expeditions, allowing simultaneous use of the two 
best small signal modes, CW and FT8, by expeditions transmitting high 
power. He developed the system so that the expedition wouldn't miss the 
one or two "magic" nights during a 2-3 week trip that generated most of 
the QSOs.

But that's a minor achievement in comparison to his Radio In A Box, that 
greatly reduces the difficulty of activating islands and other locations 
with extremely challenging access. Again, engineering at the highest 
possible level. He's been field-testing both systems for contests from 
his island in C6 for years, and is currently sailing through Oceania on 
another field test. Radio in A Box could have turned that recently very 
disappointing trip to a very challenging island into a howling success!

George is one of those geniuses who live among us and have done so much 
to advance the state of the art. I'd like to start a movement to 
nominate him for the greatest award the ARRL and world ham radio has to 
offer for technical achievement!

73, Jim K9YC

On 5/23/2023 11:25 PM, GEORGE WALLNER wrote:
> I have built, for DXpedition use,  a very selective RX front-end for 160 
> m for simultaneously operating CW and FT8 on shared TX and RX antennas 
> with 800 feet of separation. The LC filter had 8 dB loss at 1825 kHz and 
> it was about 10 dB down from that at 1840 kHz (-8dB at 1825 and -18dB at 
> 1840). That is a 10 dB difference, which should be enough to prevent a 
> good preamp from saturating.
> 
> 
> (I also built a XTAL filter that was 40 dB down, but only had a 2.5 kHz 
> bandwidth -- OK for a DXpedition that can nominate its RX frequency.)