On Apr 25, 3:16*pm, Chuck Forsberg WA7KGX N2469R
wrote:
I installed a Diamond X-200A antenna just above a Thunderbird TH5MK2
tribander. *Due to a short mast, the Diamond is virtually sitting on top
of the Thunderbird.

The lead-in consists of some 20 feet of 9914f and 50 feet of 9913,
connected with UHF connectors.

The measured SWR minimum is at 147.7 MHz and 1.2:1 at the far end of the
coax. *The MFJ 259B reads 1.9:1 at 144 mHz. *Presumably the SWR is a bit
higher at the antenna connector.

If I use a longer mast to raise the Diamond above the tribander, can I
expect the resonant point to move to the specified 146 MHz and the SWR at
144 to go down? *How much separation is needed?

The 9913 is infamous for getting water inside of it. This is usally
indicated bu an unusually low and broad banded VSWR reading. There
should be some good info on the internet about "stacking antennas" I
think some of those who loiter on this NG have written some papers on
it, I seem to remember Owen but I may be wrong.

Jimmie