These guys have a couple kinds, Resonable values too: https://vetco.net/search/results?q=n750 https://thedhtsstore.com/search?type=product&q=n750

Sing it Neil.

Hi Paul, As you your question #4, just use your imagination. Take a look at the manual for the old MMR-40 QRP rig. They use a PTO made of brass nuts soldered to a PCB just as you describe. Cheers, Mar

Hi, Any extra lead length on the finals is too much. The actual recommendation is to cut the leads short and mount the device even closer to the current PCB. If you look at any PA design, they work ha

Hi, they should fit on a typical pin header like this. Cut the middle pin short, then bend over one of the outside pins to reach the top SMD lead. Header pins are not super easy to bend, but could be

Hi David, For sure magnetic materials (ferrite or powdered iron mixtures, iron, transformer steel) will all increase the inductance when inserted into a coil. However each also contributes to losses i

Hi David, Any magnetic material could have been used to change the inductance of the air wound coil. However, unless the material is specific for the frequency being used, it will cause an increase in

I don't get it, How would brass make a good core for VHF? Its reluctance is higher than air, thus it reduces the inductance of whatever is wound around it. Logically this would result in a lower Q tha

The test would be to measure the Q of a solid 3d printed toroid vs a hollow form one, I couldn't find any posts about that, are there some here? G3YNH talks a lot about materials, but mostly relating

Ah, I expect folks were discussing ferrite toroids used in power applications (antenna and PA transformers) where designs have to be well done or else there can be high losses and/or damage to the cor

Toroids and pitfalls? What were the problems? Toroids for use in HF have been the standard for high performance vs size for a long time. Are there suddenly problems? The only problems I can imagine ar

Hmm, Digikey has like 10,000 in stock and lists them as normally stocking. So I think they will be around for awhile. Other transistors similar to the IRF510 have been tried: https://qrp-labs.com/qcx/

And Microsoft Word should read it just fine too...

Hi, Most picture formats are blocked from going in the Files section, so they should be going on the Photos section. For me too, it is much easier to set the emails to specian notice only, and then ac

Hi, The rig used tiny binocular cores for some of the transformers since the board is quite small. The holes are only 1.7mm diameter so fine wire is need for some of them (trifilar wound with 5 turns)

Hi, I didn't use the plastic variable capacitor, and looking on the web I see that they cause lots of drifting problems. So for sure try to get ahold of an old style metal one. Kabaree = cabaret or wh

Hi, Powering directly from a battery should be fine, or are you thinking about ensuring that the voltage is stable for the crystal board (or you don't have a 12v battery)? You can also try driving the

Hi Haque, Yes that sounds all like thermal drift. One would get the most drift on startup, after that the drift will stabilize but then depend on local temperature changes. You can check individual co

Hi, The manual says 18W conservatively. The final transformer is wound for 25W out though, so you may get that with enough input. But that depends on the capability of the driving stages. And the heat

Hi, Components heat as they are used so drift can initially tend to be in one direction only. But the speed of the drift can be slowed, or even reversed, by cold-spray, or by colder temperatures at ni