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Adam, No problem with the front end. Perfect waterfall. I have no problem receive but I am questioning the transmit signal. I have to find the post where Hans talked about the transmit audio is not

I'm trying to determine if i have a solder bridge between D508 and D509 diodes (see pg24 in the manual.) My multimeter is reporting continuity between D508 and D509 anodes. Is this expected or should

Dean, N2TNN <N2tnn@...> wrote: Dean, What about your reception? Do you see the usual traffic on a waterfall, or is it quieter than usual? I had a similar issue, but the received signal

Evan Hand <elhandjr@...> wrote: changes of input voltage. Maybe it would be good to add some hardware protection in future revisions... It would also be good to add an option to disable the

Peter GM0EUL <gm0eul@...> wrote: I managed to blow the finals in QDX a couple of times, but it was mostly a combination of bad SWR and too large supply voltage (around 13 V). When building my

Hi, I don't think the QDX is a good candidate for doing this, lowering the output power for 35 dB. I would not do it. If so, than you should power it from a +7V DC and add a power attenuator (50 Ohm,

Hi there, if you set the frequency to 14.020 MHz then: - in CW mode you are transmitting a carrier on that precise frequency and you receive on that same frequency by using a beat offset on

Hello Dan I did set up a test jig with an sudden change 6V to more, which I documented here: http://qrp-labs.com/qmx/smpsstep.html With the standard circuit, I tested under various step scenarios,

IMO The larger zener is a good way to go for protection against a large input voltage step. It has a nice low thermal Resistance：15°C/W Junction to Lead. For a cost of 58 cents at Digikey

Hi guys, As i cannot get the highband qdx to more that 3.5w on the lower and 2w on the higer bands I was wondering if there is any possibility to reduce the power to 0dbm so incould use it as a driver

I can certainly see the prudence in a keeping the margin of safety high, so I do understand the recommendation for limiting input voltage. I just don't think this will magically protect the Vcc and

Hi All We are on holiday nr Stricken, north of Aberdeen, this week.? I set up my QMX about half an hour ago and its doing nicely.? Its just running through an Elecraft T1 into a couple of wires

Hello Dan Regardless of the curves, it's quite easy to get 5W with 12V supply. I have often operated QCX-mini and QDX well over 12V without difficulty, even on high-bands QDX in very long JS8 overs.

I have built and operated 4 QCXs & 2 QMXs. I have operated the QCXs at 13.5-14.4 V routinely. I have never had a finals failure. Some of this is due to meticulously tuning my antenna for low SWR and

Hello Gunnar I did send you an email off-list already at 0923Z. If for some reason you didn't get that - you can also hit the "Reply to Sender" link at the bottom of the email (assuming you are

Hi all Earlier in this thread there was a comment that WSPR connections don't indicate SSB contact potential. I'm not sure how this could be? Of course it is necessary to make an appropriate SNR

Hans I see that the image is still blurred, The original is crystal clear on my PC So the web-site does something to the picture, the original size is only 49kByte If you send me an e-mail, I can

Razvan, I see things from another aspect….. with the QMX we are advised to use 12 v and no more without some cost. So far all I have seen on this site is the recommendation to use some dropping

Hello Hans, included are the PNG of the plot and also the LTSpice model, so you can play with it I guess you are familiar with LTSpice, an excellent free tool from Linear Technology. I use the old

Hello Dave I don't yet see any evidence that there is a high voltage scenario that the zener diodes protect against. The diode across the choke protects against a short 1us spike. Which one can