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Wed, 12/17/2008 - 21:11 — KB9BVN

The thing that has occupied my thoughts for the most of today is how to get my Radio Shack 22-510 Switching Power Supply to stop trashing HF and keeping me from enjoying 80m and 40m.

I found a document and I have several emails now that have given me some good suggestions, so now I await parts.

 

Comments

Thu, 12/18/2008 - 04:43 — KB9BVN

How close?

I got the homebrew VFO and the Freq counter out tonight and was playing around with it and the old ever trusty yet rusty Tek 465 scope.

My homebrew freq counter says I have a freq of 7009.54 Khz on my VFO with it fully meshed. What's real handy is my K2 says the same thing....frequency wise.

But..on my scope...VOLTS/DIV are set to 50 millivolts. And the 10X button is pushed in, and the TIME/DIV knob is set to .2 uS.

If I measure a single wave it is 7.2 squares wide.

7.2 times .2us = .000000142 seconds

1 wave/.000000142 seconds =7042253.521 Hz or 7.042 Mhz

Now I am eyeballing the scope...and my eyes are certainly no precision measuring instrument...is this close enough for scope work?

Thu, 12/18/2008 - 11:32 — NT7S

As good as it gets

That's as close are you are going to get on a CRT scope. Some of the newer DSOs have a frequency counter connected to their trigger input which can give you an accurate reading, but if you are not using that counter, even the automated measurement functions will only get you in the ballpark. A dedicated frequency counter is almost always going to be better.