RF detecting question when tweaking to max or min very low RF voltages

[Army Curtis]

Rob,

Unless there is some special situation here that I am not aware of, if you
make your adjustments to "maximize" the reading on your meter, then that is
exactly what you have done; adjusted the reading to a maximum. As you said,
you are not trying to measure the absolute value, only tune for a maximum. I
don't see that you have a problem.

On the minimum side, it is much the same, but it certainly is true that you
can often tune well below the ability of the RF probe and VTVM to measure
anything at all. Again, unless there is some special situation here that I
am not aware of, if you are able to obtain a definitive minimum with your RF
probe and VTVM, I would be tempted to call it square and go on.

If you want to be able to read RF levels much lower than the typical Heath
RF probe and VTVM are capable of, I would suggest you take a look at the
"Wide Range RF Survey Meter" article in the August 2000 issue of QST. I
recently built one of these using the PC board from FAR Circuits, and it is
a very slick piece of work. It will accurately measure RF levels over a 500
MHz frequency range from +10dbm down to -70 dbm, much lower than the RF
probe and VTVM setup can do. Of course, it is not frequency selective (but
then, neither is the RF probe). It is not at all expensive to build; final
cost on mine was less than $20.

Usual disclaimers apply. Your mileage may vary. Hope this helps.

Army Curtis, P.E.
AE5P
Nacogdoches, the oldest town in Texas 

-----Original Message-----
From: Heathkit Owners and Collectors List [mailto:HEATH at LISTSERV.TEMPE.GOV]
On Behalf Of Robert Myers
Sent: Sunday, April 02, 2006 5:10 AM
To: HEATH at LISTSERV.TEMPE.GOV
Subject: [HEATH-TEMPE] RF detecting question when tweaking to max or min
very low RF voltages

I am in the process of aligning a few devices.  Often, to optimize
things (way prior to any amplification) I have to measure very low
voltage level RF signals at various points on the circuit board.  When
at these points on the circuit board, and for various frequencies, I
usually either must maximize, or minimize, the voltage produced there
when certain other parts of the circuit are adjusted.

(snip).....
 

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