I've been corresponding with a certain antenna vendor's technical support
service and they took a rather interesting position: They do not accept
measurements from devices like the MFJ 259. Their position is that such
devices do not possess the accuracy of properly calibrated test equipment
(typically costing thousands of dollars). In their experience, they find
measurements taken with a transmitter at full barefoot power and a
quality SWR bridge to be more reliable.
I see their point. The MFJ 259 is a rather inexpensive instrument and may
have significant unit-to-unit variation. It is also affected by strong
local RF fields.
My question is this -- has anyone attempted to verify the accuracy of
these units by comparing them to thousands of dollars worth of calibrated
test equipment?
My own crude tests indicate a usable degree of accuracy with purely
resistive loads up to about 50 MHz. It's hard to predict accuracy with
reactive loads.
Comments?
Bill Coleman, AA4LR, PP-ASEL Mail: aa4lr@radio.org
Quote: "Boot, you transistorized tormentor! Boot!"
-- Archibald Asparagus, VeggieTales
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