Re: [TenTec] What makes the 238 good or any other tuner good?

["Rob Atkinson, K5UJ" <k5uj@hotmail.com>]

Thanks for the clarification Roger.  It sounds as if you originally were 
targeting matching networks in the shack at the tx.   the new class of s.s. 
AM broadcast tx have built in tuners to correct for variations in vswr on 
the lines so they can operate into < 1.2:1 and be happy.
This is partly because the tx sites are unmanned these days so there usually 
isn't someone immediately available to go out to the doghouse and adjust the 
antenna tuner to correct for changes in ground conductivity due to moisture 
changes and these transmitters are designed to trip into fault mode if the 
vswr goes above 1.2:1.

73
rob / k5uj


That would be a good name for them, Rob. In essence, the place to use a
matching network to avoid feedline losses is at the antenna feedpoint.
Although using an antenna tuner at the transmitter end of the feedline is
commonplace, it is not the best place to use it, just the most convenient.
As I indicated in a previous post, if one was to measure the mismatch on the
antenna side of the tuner, you can then get an idea of your feedline loss.
If in your case, your losses are as low as you say, you really don't need
the tuner as it is just allowing you to apparently tune out a relatively
minor reactance and feel better in doing so. In cases where the antenna
tuner in the shack is being used to prevent an SWR foldback of the
transceiver, allowing it to provide its full rated output power, much of
that power is being used to warm the coaxial feedline and the matching
network in the tuner instead of being transferred to the antenna to be
radiated. 73, Rog-K9RB

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