Where does your MFJ Antenna Analyzer tell you it IS resonating? Try a
loading coil, say 8 or 10 turns of 2" diameter, and if things get
better, that would tell you whether you need the stinger or not.
> Fellow Top Banders,
> I have a matching problem with a Rohn 25G, 160m ¼ wave vertical and am
> hoping some of you can help me out.
> <> The tower is 124'-9" in over all height. The tower bottom insulator
> is located at 4'-3" above ground level thus making the vertical radiator
> a total of 120'-6". All guy wires are insulated from tower as well as
> being broken up throughout their length. <>
> For now, the ground radial system is made of 22 each, 125' long, 14ga.
> copper wire. I plan on installing another 14 radials next weekend.
> Total number of radials will be 36 at 10 degree spacing. The soil here
> in the Sabine River Valley bottomland has a "good rating" of 15mS/m. <>
> My friend (K5ZO) and I have tried every thing we can think of to get
> this antenna to resonate anywhere in the 1.8 to 2.0 MHz range. We've
> tried both low pass and high pass "L" networks, a high pass "T" network,
> low pass "Pi" network, and a parallel inductor with capacitor, in series
> with the center conductor. <>
> The best match we were able to achieve was with a 500pF cap in series
> with center conductor. This gave us a 1.7/1 swr at 2.113 MHz. (R=64 &
> X=31) All matching efforts have been made right at the tower feedpoint.
> 1. Is the tower too short?
> 2. Do we need to place a capacity hat at the top?
> 3. Would a short stinger out the top (for added height) help?
> 4. What about all the various matching schemes we've tried? Are we
> missing something here?
> <>Any input or suggestions would be greatly appreciated. Please feel
> free to post to the group as I feel this information would be helpful to
> others as well. <>
> Thanks & 73, <>
> Steve AB5MM
> TowerTalk mailing list
l o n g w i r e . c o m
HF - DX - CW - Digital
TowerTalk mailing list