Fred, In addition to using gloves, you should buy the stuff without barbs. ;-) Last year I hand pulled 12.5 gauge barbed wire off of 1/4 mile 85 pound spools to replace some 100 year old barbed wire f

Ryan, Here's a another cheap capacitance meter design, to be added to Arv's list. Especially cheap if you happen to have a $2 Arduino Nano collecting dust. You can display the result on your host comp

Shane Justice wrote: "there was a period of time where cell boosters were marketed as boosting cell phone performance in rural areas. I've never known anyone to try them." A quick look on the web tell

#gps

Shane, So which dit are we speaking of? Originally WN7WDK around 1972, became WA7WDK when I passed General and Advanced in one go a year or so later. Never really liked that call, too many W's, and th

Those photos of polite white gloved Japanese pushers make good click bait. I click them. Such pushers apparently exist in a number of countries. Japan gets the most press, with Shinjuku Eki front and

Hans, Your Japanese co-workers were probably just trying to avoid that weird gaijin. They know all about tightly packed methods of transport. For those that don't, do a google image search for "Tokyo

George, That first resistor in the pi network directly across the transmitter output is dissipating most of the power, a little bit more than 3 Watts in this case.. Given the long transmission times o

#40m

George, You are probably best off getting those 3W resistors and building an attenuator. That way there are no mods to the rig, and it is pretty much guaranteed to work. But, if somebody wants to try

#40m

Three resistors set up as an attenuator between the QCX and the antenna would work. A 10dB attenuator would bring your 5W down to 0.5W. Another 3dB of attenuation would cut that in half to 0.25W. So y

#40m

That firmware was a demo of a difficult to implement method of transmitting SSB in a very power efficient way. Impossible to implement well on a small 8 bit processor such as used on the QCX. Absolute

#qcx

To be clear, the IRF510 intrinsic diodes plus fuse only protect the IRF510's from a reversed supply. There may be several volts across those intrinsic diodes and traces and inductors before the fuse b

For most applications, a series schottky diode of sufficient current rating and sufficient reverse voltage rating is likely best. The only penalty is a forward voltage drop of a few tenths of a volt.

That Lithium Ion board is "5S", so assumes 5 cells in series, about 21v when fully charged. Also, it does not have cell balancing, just protection from over-under cell voltage, over current. For stuff

I started out in this discussion recommending a $2 TCXO that doesn't jump around. Beyond that I hope nobody is taking me just too seriously. A rubidium standard would be fun to play with, but not wort

That's a lousy way to check the accuracy of a rubidium standard. They probably track due to experiencing the same number of neutrino hits or something. You need one of these: https://www.ebay.com/c/14

If you figure OCXO's aren't good enough and don't want to depend on GPS, a rubidium standard can be had for $250 on ebay. Accurate to around 0.1 ppb, so at 10 GHz it might be off by 1 Hz I'm sure the

I looked hard at building Don's binocular microscope. That probably would have been the best option. But not having much time, I instead opted for the AmScope SE400-Z And since Bezos is already plenty

Power grid frequency can slow a bit when they get hit with a big load. But they do try to keep the total cycle count per day a constant so clocks stay on time. The 1% error at 50.5Hz means if you are

Flux is used to remove oxides and such, exposing the surface of the bare metal to be soldered. Which means flux can be corrosive, even rosin fluxes can have acids added. All different kinds of fluxes

The old "qrp-tech" yahoo forum has been archived on groups.io, That group is locked down and inactive, just an archive. Everybody has moved over to "QRP Tech", with a new moderator. Here's a search fo