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I have the QDX from last December (rev 2 I think?).? Somehow I managed to show up on PSK reporter for the nearest monitoring stations on my first try, but nobody was responding to my CQ or acknowledging my replies.? Hooked it up to a VSWR meter and the needle doesn't budge when I hit the 'tune' button in wsjtx, tested in both 20m and 40m.? Receive seems to work fine, I'm decoding ft8 just fine, but all I can do is listen.? Any recommendations for where to start with troubleshooting??

I am not sure I understand what you are reporting.? When you say the VSWR meter doesn't budge, do you mean when in setting the forward power mode??

It also helps to know the firmware installed on the QDX.? You can get this using the terminal program on the startup page or reading the file names when the QDX is in update mode.

It would help if you could tell us what the input to the QDX current readings are on receive and transmit.?

I suggest you have a dummy load connected to your QDX when doing any testing, as it is easy to damage the BS170 MOSFET finals.

Since PSKReporter has spotted you, you are putting out some power.

73
Evan
AC9TU

On Fri, Aug 12, 2022 at 12:01 PM, Evan Hand wrote:

I am not sure I understand what you are reporting.? When you say the VSWR meter doesn't budge, do you mean when in setting the forward power mode??

Sorry, I misspoke, I was using a?Thruline Wattmeter, set up to measure forward power.? The QDX was connected to a dummy load through the wattmeter, and I was clicking on the 'tune' button in wsjtx to key up the radio.?

It also helps to know the firmware installed on the QDX.? You can get this using the terminal program on the startup page or reading the file names when the QDX is in update mode.

I'll update with that info later this evening.

It would help if you could tell us what the input to the QDX current readings are on receive and transmit.?

If memory serves, the radio was drawing about 0.12 amps in receive and about 0.25 amps on transmit.?

I suggest you have a dummy load connected to your QDX when doing any testing, as it is easy to damage the BS170 MOSFET finals.

While testing I was using the dummy load kit from Hans

Since PSKReporter has spotted you, you are putting out some power.

I haven't tested it with an antenna since before I connected the wattmeter, maybe it worked briefly and then stopped because it was damaged.? I suppose it's possible I'm not using the wattmeter correctly.

Thanks,?
Phil KC2WAN

Phil,

OK, now I have a clearer picture of what you are telling us.? You have a low current draw on transmit, so the power amplifier MOSFETs (BS170 Q8, 9, 10, and 11) are not drawing power.? That could be an L14 or T1 problem and other issues.? Verify that you have the input power (12, 9, or whatever you are supplying) on the 4 MOSFET drains.? If there is no power on all 4, try reflowing the connections for T1 and L14.? That is the most common problem.

Did you do the continuity check when you installed T1?

I should have started with the obvious.? Have you verified that the LED flashes 3 times, then pauses and repeats?? That would indicate that the audio level is not set high enough to measure the frequency.? This is not an issue if you use the Terminal Program Transmit test application.?

I suggest you set up a terminal emulator on your PC to help with the diagnostics.? For Windows, I use PuTTY.? Available here:

There are other options for other operating systems.? I have not used them.

We can start here and see what you find.? As stated in my prior post, always have a dummy load or resonate antenna connected when the QDX is power.? This is especially true when testing for problems—transmitter test I always do with a dummy load first.
73
Evan
AC9TU

Putty works well in Linux as well.?
--
Colin Kaminski - K6JTH
https://www.qsl.net/k6jth/

Thank you for your assistance and your patience.? I'm ashamed to say the culprit was at least one cold solder joint on T1.? Don't know how I overlooked that.? Finally got around to fixing it, and this weekend I had my first HF contacts using my own equipment.? Had an FT-8 contact with a station in Croatia from SOTA summit W2/NJ-012. Thanks again!