I have completed my QMX tx works fine on transmit but there is no receive on any band.?

Attached a picture of the configuration screen. It looks like it's permanently on transmit, what would be the cause?

Thanks anyone for tips.

Paul DJ0CU

开云体育

To put it another way, what does the same screen look like on a unit that is working normally in receive. Thanks

Paul DJ0CU?

开云体育

Like you posted.

Thinking a bit more the things involved in Rx but not Tx are the band pass filter components L401 and it's associated capacitors and the trifilar transformer T401.

The sweeps in the diagnostics are useful to check, if they are all giving a low max value that's an indication of a lack of connection.? Check the soldering of the toroids, everywhere, it's very easy to fail to get the enamel off.? I had this and redoing the soldering fixed it.

Chris, G5CTH

Roger, I've been through the connections with a fine tooth comb, but no harm in doing it again., but it would be nice to know if "transmit enabled" should be permanently showing, as in my case, doesn't seem right.

Paul DJ0CU?

Hi Hans,

Yes transmit works fine, I've been heard at good strength on all bands right into the states on reversebeacon etc., just that receive is dead as a dodo? ;-(
but good to know, transmit enabled is ok on receive.

Paul DJ0CU G4ADF

Mine had no receive as well. Turned out C509 was missing entirely which may be the cause for both of us. I will know soon as a replacement should arrive today. C509 position is on the bottom side of main board right next to R510 which is marked "103."

73
Karl
KI4ZUQ

Hi Karl,

no, on my board c509 is fitted, sitting snuggly next to R510.

Paul DJOCU?

Check the voltage at C406. One is ground the other should be about 2.5v.

-mike/w1mt

Okay. Now you know one thing it AIN'T!

?? true

yep, that's what I'm getting. attached is audio scan, looks bad.

Paul DJ0CU?

Ensure that you have 2.5v at each solder joint for T401.

-mike/w1mt

What is you transmit power into a dummy load for each band?

-mike/w1mt

I'm not sure would have to check, but with 12v I'm getting between 3 and 4 Watts input on each band when connected to an aerial.

What do the RF Plots look like?

-mike/w1mt

?It counted up to a 100 , then I just got a blank screen and the QMX crashed

Do a factory reset and try again

Tried that, no change. Below couple of screen shot, maybe they tell you something? I have no idea?
Thanks Paul DJ0CU?