Re: [Discuss-gnuradio] AOR 5000 as front end to USRP

[Eric A. Cottrell]

Eric Blossom wrote:
> On Sat, Dec 30, 2006 at 07:23:19PM -0800, Matt Ettus wrote:
>> Eric A. Cottrell wrote:
>>> Hello,
>>>
>>> Does anyone use a AOR 5000 as a front end for the USRP?  The docs for
>>> the USRP say that it is not very sensitive but I thought the IF Output
>>> from a AOR 5000 could drive it.  It seems to work for strong signals but
>>> I am getting the impression that a 10 dB or so amplifier would improve
>>> the situation.
>> Did you turn up the RX PGA gain?  You can get an additional 20dB there. 
>> Also, the BasicRX and LFRX inputs are 50 Ohms.  Can the AOR drive that?
> 
> On my AR8600, I need to use 10 to 20dB of gain between the output of
> the 8600 and the USRP basic rx.  It depends _highly_ on which band
> I'm tuned to.  BTW, on the AR8600, there's a slight mod you've got to
> make to the board to enable the IF output on all the bands.
> 
> Eric
> 
Hello,

Thanks to both of you for the information.  I got the RX PGA gain up all
the way.  I rewound the isolation transformer to be 1:1 with 14 turns.
I still have to turn off AGC for good signal levels but I got 20 to 30
dB SNR on RCI at noon today.

Doing some simple tests with the PSD display in DReam I can not see the
  noise floor increase when the receiver connected.  The FFT from the
USRP data also shows no increase so an amplifier is needed.  What
amplifier do you use on the AR8600?

Everything is jury-rigged so I need to sit down and design an real
circuit.  It is getting better.  It was frustrating to hear good signals
and get nothing.

I also have an AR8600 and an Icom R-2500.  Someone modified a R-2500 for
IF Out and mentioned strong signals.  I may try that as well.

73 Eric