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!

72/73,

Joe E., N2CX
from Southern New Jersey, y'all
home: n2cx@voicenet.com