Gang,
I promised to let folks know about the scope mixer device that was published
in the Jan '97 73 Magazine. It is now working and I can say it is a very
interesting addition to the operating desk. I can now see my signals as they
go out. I was able to easily check the waveform of the 38s output, and could
easily tune it to a clean signal. I had it right in the first place,
incidentally, so don't worry--if it sounds clean on the big rig, it is
probably ok.
This device is a variation of the one in all handbooks except it is even
simpler and uses a 2N2222 as the mixer instead of an expensive mixer device.
As usual there is no free lunch. The unit uses a ferrite loopstick (now
where did I put that loopstick in 1956?) which I didn't have--cost about 7
bucks from antique radio--see the article for their info.
The other half of the system described in this article is a very good
adjustable unit for sampling and switching the station's RF output and
together with the mixer, the two units are good for 100watts down to about
200mw. Pretty cool, and it seems to keep sampled voltages well in the safe
range, regardless of input power. And it also doesn't seem to affect QRP
operations on the air. (That's just in case I find time to actually
operate.) Pretty cool, and I feel it was worth the bench time. I am using
an old OS-2 Navy scope for this as a dedicated shack monitor. The good Tek
scope will remain at the workbench, where it is most useful.
Even if : a) you don't need to extend the range of your scope b) don't like
to build from scratch c) don't plan to look at your output : this article is
still good reading. And if you need some or all of the above, or need a good
system for sampling your RF output without risking your existing scope, you
will enjoy the article.
Next project: The Steve Weber Spectrum Analyzer/Scope Adapter.
72,
Preston WJ2V
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