JT,
Most of the times that an analog meter is helpful is when making peaking
adjustments to tuned circuits, so what you really need is a meter system
that can detect and display the amplitude of an RF waveform - the
following are suggestions:
For a *really* fast responding 'analog meter', use an oscilloscope - the
vertical deflection represents the voltage - the advantage of the
oscilloscope is that it can work at low RF voltage levels as well as
higher levels.
Many DMMs have an "analog" bar graph display that is fast responding.
Use in conjunction with an RF Probe. An older VTVM will suffice instead
of the DMM, but also will likely be used with an RF Probe in most
cases. Note that a VOM will not work very well because it loads the RF
probe output significantly.
An analog meter SWR meter will measure the relative level of RF at the
transmitter ouptut - the peak is easy to see when making adjustments.
This one is already available in many hamshacks and will suffice nicely
as long as the transmitter is working.
A very nice meter for measuring RF directly over a wide frequency range
and from very low levels to quite high levels can be homebrewed - see
the article from QST June 2001 page 38 titled 'Simple RF-Power
Measurement' by Wes Hayward W7ZOI and Bob Larkin W7PUA. Fitted with an
analog meter, this instrument will measure from nanowatts to a
milliwatt, and when used with a 30 dB coupler like the Elecraft CP1, the
range can be extended up to about 10 watts, or with the 40 dB Tap that
is shown in the article, the range goes up to 100 watts. A very nice
instrument indeed, but be careful to shield the input well, this is a
VERY sensitive meter.
73,
Don W3FPR
JT Croteau wrote:
W3FPR and others frequently recommend good quality analog meters for
doing several alignment procedures and for performing countless tests.
I'd like to get one but have no clue what to look for in this day and
age of digital test equipment.
Advice, recommendations please?
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