Topband: Shunt feeding AB-577/621

[Dick Green WC1M]

Hi Pete,

Good question. I haven't done it with any of my three AB-577s, but I've seen recommendations from others that the sections be electrically bonded. 

I'm not sure about the case for that. I just measured continuity on the flat portion of a spare tube and it showed zero ohms. If the contact areas are clean when the mast is assembled, they should make good contact with zero resistance. The clamp should act to keep the flat areas in contact, as should the downward pressure from the guys. I guess it may be possible that dirt carried by rain water might seep into the clamp and get between the sections as they rock back and forth in the wind, even if it's just by nanometers.

If you buy that possibility, I think it can be overcome pretty easily by attaching right-angle tabs to the top and bottom of each section with screws/nuts, and running a section of copper strap between them, also secured with screws and nuts, or perhaps you can find some sort of clamp that would let you quickly connect/disconnect the strap as you raise/lower the mast.

Hope this helps.

73, Dick WC1M

-----Original Message-----
From: N4ZR <n4zr at comcast.net> 
Sent: Monday, October 1, 2018 11:48 AM
To: topband reflector <Topband at contesting.com>
Subject: Topband: Shunt feeding AB-577/621

I have an AB-577 with a C-3E on top, and am interested in the possibility of shunt-feeding it for 160 - 100 watts only.  Anyone have any experience with doing this?  Are the section-to-section joints adequately conductive?  I would plan to use an omega match, because I'm guessing it would be well short of a quarter wave.

My other option is an inverted L.  Should I maybe just go ahead with that?

-- 

73, Pete N4ZR
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