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Hello,

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I bought a QDX used and never got around to using it. What is the best way to tell what voltage it requires and if it is high or low band? I believe it is 12v and low band, but not 100% sure. It power on ok with different voltages, and wsjtx allows me to select any band. I didn't want to try txing since I might be using the wrong voltage.

Thanks!

Power supply voltage does not matter for RX. It only makes a difference on TX. You could try and figure out how the output transformer is wired, but that is difficult without removing it. I would suggest powering it at 9V and seeing what the power output is. If it is a 9 V unit, power should be 4-5 W on all bands. If it is a 12 V unit, power will be about 2-3 W.?

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73, Dan? NM3A

Hello Dave,

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Dan's suggestion is good with one addition:? do the test into a 50-ohm dummy load.? Antennas can cause higher or lower power due to differences in impedance.

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73

Evan

AC9TU

Toroid colors indicate a low band build. The high band QDXs never came with any red toroids. So likely an 80-20m. 12V build is the most common I think, but as was said, try 9V and check power output.?

You could go into the serial terminal application (putty) and connect to the QDX and look at the band configuration to confirm as well, as far as band setup.

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As always, I'll suggest the diode across L14 mod, too. :-)

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-Nate

N8BTR

Evan,

LOL! I made the silly assumption that a DL would be attached.?

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73, Dan? NM3A