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It seems any photos attached to a thread are gone after a couple of weeks? So instead of posting my handheld QMX photos here again, I recommend you to visit my QRZ page to see how I'm operating QMX as

Hans Could you take a moment to let us know the status. I'm sure there are lots of eager to get it. Thanks

Ludwig, thanks again for reply! The QMX QMX_plus Startup ( /g/QRPLabs/wiki/36878 ) is good advise. I will try to measure some of those voltages and the currents as well. But still, I

Try putting a simple 50-150cm whip antenna on an HF TX and then measure the performance / narrow bandwidths / low effiency / variable impedance due to numerous external factors whilst actually

So, what I did while using an old crystal controlled transmitter, combined with an SDRplay RSP-1, was to put an RF triggered TR switch between them. That could be done with a transceiver like the QMX

This might interest some. It could be used with a switch that turns this receiver's RF input off when the transceiver is transmitting. Several companies make these switches. "Could This Be The BEST

Somehow, handheld HF is an under-served market segment. I have seen some very nice modifications in this group and I tried myself but failed, I end up brought a KH1. If you have a full-time job and

Perfect solution Joe, thanks for sharing. Will keep your idea for when I get my QMX+ Cheers. Gert

Thank you all, for your valuable replies! I did, indeed, only read the QMX docs - even though it is mentioned on various locations that one design is based on another so now I have to ask myself why I

Hi, It can be done using an electronic T/R switch in parallel to the antenna port and controlled by a PTT signal. I have used this with several QRP radios feeding a RSP1A SDR. 73, Roelof, pa0rdt

The receiver gets RX_IN from Q508 in the upper middle of the final page of the schematics (page 5). Q508 is where the transmitter is blocked from the receiver, though there will still be a very strong

This is SDR, the IF is 12KHz. Thinking about it the IQ appears at IC407 input in normal mode. The RX antenna is switched at Q508. I am reluctant to suggest anything, I have not tried it myself. I

This tread has hit a nerve.? I plan on doing something like this with my QMX+.? Proposal is to use a hi-z input buffer board at the receive frequency inside the QMX+ and send it to an AirSpy

See also this post from a few weeks ago. /g/QRPLabs/message/139008?p=%2C%2C%2C20%2C0%2C0%2C0%3A%3ACreated%2C%2CHandheld%2C20%2C2%2C0%2C111206911

And if you want to do it fully externally,? the QMX does have a PTT signal output that you can use for rx/tx switch.

It's all here including common mode choke - except the whip which is inefficient. Since the radiation with a whip is mostly from the counterpoise, I am using an EFRW of 10m or more (no counterpoise,

You can read more about the QMX receiver design in the QDX assembly manual - Hans did not repeat the design description for QMX. As others have said, there is no real IF.? If you really want to

Matti, please read QMX QMX_plus Startup ( /g/QRPLabs/wiki/36878 ) to find the switch on process. There you will find also some testpoints and values to check. How much supply current

Its been mentioned and can be done...save for that pesky antenna. At 10M a moderately decent antenna is 8ft long.? However at 40M anything that's under about 16ft long is about as efficient as

For some of us, the priority here is operating. For others, it is learning and understanding how this fascinating radio works. Personally, I have never had much interest in operating. I do most of my