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Rob, If L7 is not broken (47uH), then also check Q4 BSS123. -- Gyula HA3HZ

Hi all, Last week I built the QDX Hi feq. Version? 5 for 20m, 17m, 15m, 12m, 10m. Blue/ yellow toroids. At 12V. On all frequencies I get more than 4w output, except 15m/ 21Mhz. on a? 50 Ohm dummy

JZ, Tony is saying that the frequency where the peak is expected is off, not the impedance measurement is off.

I'm not sure if this is the same with QDX, but QMX's 6-layer board, assuming FR4, can have about 25pF per square centimeter on an inner layer if sandwiched by ground or supply planes (13pF if on the

Tony, I have never tested my NanoVNA to figure out the range of impedance measurements it is good for. I'm sure there is a limit somewhere but where? JZ wrote:

Completely speculative here, but winding capacitance, the leakage inductance or both may be affecting the apparent input impedance you measure. Can you add a 10pF or 22pF or something in parallel to

? I don't understand what you are getting at. TOny ________________________________ Sent: Sunday, October 22, 2023 10:11 AM To: [email protected] <[email protected]> Subject: Re: [QRPLabs] QDXH Tayloe

Tony, Might the next few data points have taken the NanoVNA above its range? JZ

Photo? 73 Jim N6OTQ wrote:

I do not understand why the impedance is peaking at 28052. I checked the LO with my GPS locked SDR and it is at 28062 which matches up with a 12KHz IF and being tuned to 28074. I checked the nanovna

Hello Derek Yes! Yes! 73 Hans G0UPL http://qrp-labs.com https://buymeacoffee.com/g0upl

I ordered an assembled QMX with a case.? When it arrives, will it be installed in the case and will it already have the firmware installed?

Like this, Ryuji: Clock at 1 MHz Bandwidth set narrow, 1uF integrating capacitors Ten runs, stepping in 1KHz increments from 990 KHz to 999KHZ Plotting the beat note developing at one of the

OK Alan! That ties the ribbons on it, I think. Thanks for the good info...JZ

Yes, John. The first firmware kept the 12KHz offset in IQ mode but that was not easy to cope with so Hans removed it. I'm beginning to think straighter, the LO can not appear in the centre of a

Good. Frankly, there's not much else to look for practical purposes. We already have enough clarity in this area.

I'm ok with keeping one hand on the volume but I did think about making a simple passive AGC circuit. If I use a LND150 (depletion + enhancement mode MOSFET, normally halfway on when VGS=0V) and a

Nope... It's not difficult to just make multiple simulation runs with different input frequencies to get a good idea of the response at baseband.

Are you guys now trying to feed white noise to the mixer and do the spectral analysis of the I/Q raw signal output for the mixer's frequency response??? (I don't recommend fake impulse for this.)

Good advice! I had the blast in my phones as you did. I too have had tinnitus for 50 years. Too much time in front of an elementary band! ‘73 Jim WX8J