[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: [linrad] A simple front end

Hello again Roger
I note that the R2Pro site prices the modules individually.
LNA (specify band) $12
Down converter $52
Analog processor $38
1 kHz filter $15
3 kHz filter $14
Audio amp $16

All together for $115- pretty good value it seems to me

Boards only $25

Thank you Leif for the tip about a cheaper way to get the +/- 45 degree phase shifts. I calculated the relevant component values for 14 MHz as I want to try the DC design for the first time.

Hi, Leif!

Welcome back!

Yes, your "?????" and what you say [excerpted below] is really the point I was
To make a longer note to explain what I was saying in the original email:

The R2Pro consists of, in order of signal transit:

Low Noise Amplifier Board

DownConverter Board: TUF3's in quadrature followed by diplexer, etc.

Analog Signal Processor Board

Audio Filters

Audio Amplifier Board

The DownConverter Board has its diplexers just after the TUF-3's, and they roll off
quickly [4000 Hz?].

So you are I believe using only the RF amplifier board and the TUF-3's and throwing
away everything else if you use the R2Pro for Linrad. This makes this route a
relatively financially inefficient way to go and wastes a lot of parts and effort.

I couldn't see taking the R2Pro and using just the RF amplifier and TUF3's and
wasting the boards and everything else.

It would of course be possible to redesign things and change the frequency response
of the DownConverter Board from 0-4000 Hz to 0-90 KHz, and alter the subsequent
stages as well, but I felt that if I was going to do all that, it would be just as
well to start from scratch. Thus my comments.

It would be possible to use just the LNA board with no mods followed by the remainder
of your own front end, but buying the R2Pro just to get the LNA board is an
expensive way to go vs just building that alone.

There are some pages on the R2PRo at:


They don't have the schematics. I DO have the schematics, but I don't have
permission from Rick to post them.

 > It is the audio phase-shift network
 > and diplexer that I thought would not have the necessary bandwidth.
 ????? These parts should be bypassed. Do not sum the signals in the
 analog hardware - that is for Linrad to do.

Any and all comments / corrections are appreciated!

Roger Rehr