[hpsdr] ANAN 10 28Mhz tx spectrum and generated birdie

[Helmut]

Hi guys,

 

Please don't complicate a technical discussion with marketing details. As
already reported I measured different boards (produced by TAPR, Apache Labs
and Gerd, DJ8AY). All boards show sufficient harmonic suppression at 500mW
output on 28 MHz: > 50dB at 2f, >38 dB at 3f. And - to disagree completely with
Abhi's opinion - the sole Hermes board and of course all other HPSDR boards
are perfectly suited as driver for transverters using 28 MHz or other IFs in
the 1. Nyquist zone. No additional LPF is needed!

I'm using a 432 MHz transverter with (only) 28 MHz IF of Hermes for small
signal SSB without any issue. Of course the transverter is well designed and
provides an appropriate Helixfilter in the 432 MHz path between the LNA and
a double-balanced 17dBm mixer. Moreover this mixer is well matched on the IF
port!

 

I guess Dom's problem can be reduced to the search of the source of the
birdies.

 

73, Helmut, DC6NY

 

 

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