Application Note #11

Subject: Limited Rainbow Tuner Use with the Hamstick

A number of hams have asked a question along this line:

"Has anyone tried using the rainbow tuner on a hamstick to tune it in? I have a portable made out of a Hamstick with the counterpoise on it but can not seem to get its SWR to come down. It stands on top of a 12' mast and the counterpoise is conected to the mounting bracket. SWR is up above 3:1 and I can not get it to come down. I am in hopes of using the Rainbow to help bring it down."

Well, I'm afraid you won't have much luck using the Rainbow tuner with a Hamstick.

The tuner is not a general purpose tuner, it is intended for high impedance end-fed half waves. The Hamstick, on the other hand, looks electrically like a low impedance quarter wavelength antenna at resonance.

There *are* some thoughts in the Rainbow manual on other network confiugrations that may assist you provided that you don't mind modifying the tuner. Something like the series resonant configuration in Figure 7 may work with the Hamstick. It may have a limited tuning range, though.

Please feel free to experiment. I don't want to discourage that, but felt that I must confirm the design goal of the tuner so that you don`'t get frustrated in a nearly impossible situation.

Please report your successes (and failures, too) to this group. We are all interested in learning!

Hope this helps!


Joe E., N2CX
from Southern New Jersey, y'all

Last Modified July 31, 1997 - George Heron, N2APB (