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I'm on the verge of buying a QMX+; the technology is just too good to pass up!? I had misgivings about the QMX because it didn't cover every band and also because of its small size. ?My camping and backpacking days are long over, and everything I do now is from the comfort of my home shack.

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My main mode of operation now is FT8/FT4, and I'm using my FT-817 for that. ?My intent is to try the QMX+ in that role. ?

On the '817 you can select different RF output levels by cycling through the available levels using a function button. ?I generally start a contact using 2.5 watts and then bump it up to 5 watts if there's difficulty in completing the contact. ?Just pressing the button once changes the power to 5 watts. ?

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I don't see anything like that on the QMX+. ?

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So here's my question: How do you change the output power on the QMX+? ?Is there a menu function to select the power? ?Or can the output power only be adjusted by changing the supply voltage? ?What's everyone else doing; do you just leave it at the same power level, or are you using some means to adjust the output power as needed for each use??

Larry, WA2VKG

Larry,

The output power is affected by the input voltage, within limits. If you have a QMX+ that's built for 12 volts, then the highest voltage you should power it with is 12 volts. The transmitted output power is going to vary a little from band to band and from build to build. I get about 4.5 watts out on 30 meters, but about 3 watts on 10 meters. I can use a buck converter reduce my input voltage to as low as 7 volts. Maybe you could go a little lower than that, but it seems to operate reliably at that level. That significantly lowers my output power, but I can't remember now what I get on each band with that.

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73, Dan - W2DLC

Unfortunately there is not yet a firmware control to adjust the output power during operations.

The hardware capability is present, so we can hope for a future firmware update that will allow us to change the % of full output power we want to use.? (Currently that is only available for 'tune' mode).

Stan

Dan & Stan-

Thanks so much for the info.? I'm new to the group and I sure appreciate your quick response and all of the info in this group (I've been reading all of the posts in the digest).

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I guess I either need to give up on the idea of adjusting the output power from contact to contact as I'm doing with the FT-817.? Afterall, there's probably not much difference between 2.5 and 5 watts anyway.? I'll just power the QMX+ with a safe voltage (maybe 11.5v) and take whatever the transmitter gives on that band.? Maybe another option is some sort of variable supply (adjustable between 7 to 12.0v).? But at this point I think I'll just take the "quick and dirty" route and use a string of series diodes to bring my 13.8v supply down to something safer (11.5v).

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Question:? How much current does the QMX+ draw on transmit ("worst case"... key down, 12.0v input, max output power)?

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OK, one more question:? Does the output power when using WSPR behave the same way?? The WSPR transmission includes output power (dB); is there some way to actually control that or do you just send whatever the QMX+ happens to be putting out at that frequency / power supply voltage?

Larry,

My QMX+ draws about 11.4 watts on transmit on 20 meters, putting out 4.5 watts.?

That's what I'd expect to see, about an amp at full power.?

I hate to do things like this, but you could just eat that extra wattage coming out of the back of the radio with a step attenuator rated for the power. Building one would be easy enough to do if you can't find one made already.

73

Frank

AA5IT