July 2017

SWR Meter rebuild

From a bunch of stuff some other ham wanted to throw away, this ex-SWR meter.


I have no idea why the Dreaded Previous Owner stripped it down to this state. The meter movement is fine, 950-ish mV over a 4k7 resistor gives FSD, so it’s a 200uA unit.


The detector components are still in place, and it looks very similar to the Micronta 21-520A except that there’s only one meter. There’s also a little bobbin on the side for an antenna, presumably to make it into a Field-Strength Meter, but that’s a gimmick and won’t happen.


The junkbox yielded two switches of the right type and size (one selects Power / SWR, and in SWR mode the other selects Forward / Reverse). There will also be a pot to set FSD in Forward mode after which the Reverse mode should give the SWR. Give or take. Don’t expect a lot from meters like this.

Fast forward a bit and we have



Don’t ask me what used to live in those two extra holes. This setup works for me, for the price of a few junkbox parts and some time.


New toys

Orms was advertising Canon 100D bodies for R3 795*. I wasted no time to get one (should have snagged three). They also had a number of second-hand  EF 70-300mm 4-5.6 IS lenses, priced from R3 800 to R5 000. All rated “80%”. I took the R3 800 one.

And then I chanced upon an EF 50mm f1.8nifty fifty” on Gumtree for R1 200. I had to get it mailed down from Pretoria, which cost me an extra R100, but that’s how it is. It allows me to do things like this.


Available light, 1/80 at f 4.0, ISO 4000. Lightroomed to bring the eyes out a bit, here’s a strip at original resolution and no processing.



Toothless the black cat, however, is still impossible to photograph.

  • I suspect this was a typo, because the next week they had these same bodies on special for over R5 000.

This… is stupid

(IMO, of course. And Geek Alert)


This is the switch and tuner schematic for an MFJ-949E Versa Tuner II. Great little unit, with a built-in dummy load. It has a switch that selects the dummy load, then the three antenna connectors in pass-through mode, then the three antenna connectors through the matching network, and then the dummy load again… through the matching network.

Which means that if you want to tune into the dummy load, you have to use the setting all the way to the left, or you have to adjust the tuner to match the dummy load to the rig, using the switch setting on the right.

Now why would you need to match a 50 ohm dummy load to your rig? Insane. The dummy load switch setting on the right should connect straight to the dummy load, not via the tuner.

I have a soldering iron, I can fix it.