开云体育

The sort of thing that running at a lower voltage could help with is a short? from gate to drain on a BS170. Less than 5V could preserve the driver IC503. ? It may be detected by the lack of

I wondered this too. In the end I just tried tacking one joint in place and adjusting until it gave a good fit in the case.

If someone could post the waveforms from their centre tap on T501 as well as the BS170 drains that would be very helpful as a reference!

OK Guys, D108 replaced with 5,1V Zener. BS170?s replaced (not because they were defective but because I initially unsodered them). Fixed a few solder joints, and QMX is in Service. Had first 2 CW

The page shows the orientation where Hans has pictured the diodes. The board is very hard to read for sure. I just go by the manual picture and it works. 73, Cliff, AE5ZA

The instructions say "The white stripe end must be aligned with the white stripe on the image of the PCB silkscreen" .? There are two white stripes that form a > or <.? The photo is over directly

Three weeks ago I was trying to get more power out on 20M QMX. It was running about 2.75 watts. I did the capacitor swap and actually lost about 1/4 watt. Next try was to squeeze the turns on L513.

Some math: The drain waveforms of each bank of BS170s go from 0 to 26.4V. Since there are two of them across the input to T501, that means the input waveform (ignoring the centre tap) is 26.4 * 2 =

Hi Mike It's also on my ToDo list... 73 Hans G0UPL http://qrp-labs.com https://buymeacoffee.com/g0upl

Hans, Follow up to this. When you change bands the frequencies aren't remembered. What are you thoughts in this case? -mike/w1mt

Hello Cliff I haven't noticed any of the issues you mentioned but will try my best to reproduce them tomorrow. The default startup frequency on QMX is just the last frequency you were using when you

Hi Andrew Not going into G (auto practice mode) when already in P (practice mode) is also the way it works in QCX. The original idea of detecting the GPS being detected was about protecting the

Thank you for all your help John :) I am similarly puzzled. This morning I tried replacing a few of the SMD components closest to the T501 leads in case some of them were cracked, but this did not

Rob, Look at page 24 of the assembly manual. It tells you how and shows a picture of how they go. 73, Cliff, AE5ZA

Hi Colin I'm pretty organized about listing all the changes I've made. Generally if it isn't in the list then I haven't got to it yet. As in this case of the volume ;-) 73 Hans

Does the "handedness" of the 10 turn windings on each end of T507 matter? I can't be sure how they are done on the photo on p. 40 of the assembly manual. Tnx es 73, Randy, KS4L

I'm trying to determine the diode orientation for the #QMX. I can see 2 tiny white marks between the holes. The appear to form a < or >.? Does the white stripe side of the diode go towards the closed

A sad case of Murphy's Law. The MCU is the one thing you cannot replace. I hope you find that the fault is something else. JZ

John, While making these measurements, plug-in PCB #2 was pulled, so D109 was not in play. My current limited supply was injecting 3.3v (current limited) directly to the main board. ?There is a

Bill, I am probably wrong but I don’t see how starting at a lower voltage will create any less chance of issues than full voltage…. may just prolong the inevitable. Yes, it may not smoke a part