Re: FDM DUO INCREDIBLY NOISY!!! #fdm-duo

Neil Smith G4DBN
 

No they are not like that Tom. I use mine for extreme weak signal work on VHF/UHF/SHF and on LF and it is one of the best performers I have ever used.

Hard to say what is wrong though. The DUO is extremely sensitive compared with many analogue radios, but with the AGC set correctly, it should behave itself unless you are overloading it.

What level in dBm does the display show with no antenna connected and with it connected?

Any sign of the PK indicator showing? If so, does enabling the RX ATT menu 1 make any difference?

If you are not using narrowband antennas, you need to make sure you are not overloading the wideband front end with broadcast signals or anything. If the PK indicator is showing, then you have strong out of band signals that are delivering more than the approx -10dBm total signal that the ADC can handle.  This applies to any SDR of course.

If you are seeing PK overloads, then you need to think about how to reduce the level of the interfering signal.

If the PK indicator is NOT showing, then try these:

Does the noise level change if you connect the antenna, or is it bad even with nothing connected? 

Does it change level if youselect antenna 1 or two on menu 31?

Is anything else connected at all? (keyer, PTT out, ref in, USB etc?)

What settings do you see on tthe E1 control?  Mine has SQL OFF, AGC ON, AGC FAST, AGC TH 3, NR OFF, NB OFF, AN OFF

How about E2? I have RIT OFF, FIL 2700, PITCH 600

I am in USB mode.

See what happens if you adjust the AGC THreshold.

Let us know what you find.

Neil G4DBN


On 05/11/2019 13:26, m7mcqio83ro@... wrote:
Hi all, I just bought a used FDM DUO and when I plugged it in last night at home, it was incredibly noisy!! I thought there was something wrong with my G5RV or with the existing settings in the transceiver, so I performed a DEFAULT RESET and it was just the same.

So a few minutes ago during my work-break I drove up to a high vantage point and connected it up to a LifePO battery. It was nice and quiet.

As soon as I sat back in the car though, it was back to being incredibly noisy with the ignition switched on (but engine not running).  I've had lots of radios and NONE have been noisy like this one. It's soooo poor! 

Are they all like this or have I bought a duffer??

73, Tom. M7MCQ

-- 
Neil
<a href="http://g4dbn.uk/"><small>g4dbn.uk</small></a>

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