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 BBS: Music City Archives (Line 1)
Date: 08-09-93 (17:04)             Number: 10633
From: MIKE TONERI                  Refer#: 6926
  To: TOM HAMMOND                   Recvd: NO  
Subj: Mfj Tuners                     Conf: (50) HAM_TECH
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 -=> Quoting Tom Hammond to Mike Toneri <=-


 TH> Often, arcing is a result of mis-tuning of the transmatch.. regardless
 TH> of who manufactured it... there are certain inductor/capacitor
 TH> settings which DO provide for low SWR, BUT which also will cause
 TH> excessively high RF voltages to appear across the components (esp
 TH> capacitor plates and switch contacts).. thus arcing occurs.  Quite
 TH> often, just re-tuning the transmatch, using a different set of
 TH> inductor/ capacitor settings (and yes, you CAN usually find at least
 TH> one or more additional settings of the transmatch which will produce a
 TH> low SWR) will help to solve the problem.

 I am aware that there is usually more than one setting that will
 produce a low SWR, having been a Ham for over 30 years and mainly
 interested in antennae and antennae performance. The MFJ 300 watt
 tuners are really not quite robust enough to handle even a small amount
 of mis-tuning on some antenna and power levels.

 TH> As I recall, try to find a tuning setting which uses MORE (rather than
 TH> less) capacitance (this usually also implies LESS inductance).
 TH> ALSO... make sure you know which end of the capacitor scale (on the
 TH> front panel) indicates MAX capacitance.  Some transmatch manufacturers
 TH> (for some unknown reason) place max. cap. at 0 on the scale and min.
 TH> cap. at 10 (or 100).

That's the first thing to check out on an unfamiliar tuner. It can
really get you screwed up sometimes.


 TH> With MFJ, as with some other companies, if it seems to be too good a
 TH> deal, it probably is.  Transmatches are not (IMO) a good place to try
 TH> to save a bunch of money by buying the cheapest device... buy the one
 TH> you'll want to keep for LIFE!

You get what you pay for most of the time but with MFJ you sometimes get
a little less. As for the 1 - 2 KW rated tuners, they appear to be well
constructed and will handle the power that Hams are allowed to run. The
old Johnson is rated at 1KW amplitude modulated continuous service so
you know it won't break down and arc over at high power. Even so, it
always makes good sense to do your tuning at reduced power levels.

73...
    Mike VE3FGU


... Real radios glow in the dark!
--- GEcho 1.00+
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