In a message dated 98-04-14 23:59:23 EDT, you write:
> What is your take on the following antenna situation:
>
> I currently use a TH7DX at 50' on Rohn 25. I have in storage a Rohn
> tilt-over tower (68'), an unused Force 12 EF420, and a Big Horn 4 el 15M
> delta loop beam (the only one built, I believe, on an 18' boom).
>
> Do you think it is worth the extra hassle of putting up these
> monobanders on the tilt-over (when I move) or will it be just about as
> good but with less potential trouble to continue using the TH7? (My
> main interests are IOTA and 80M--only need 3 more all time countries and
> 12 zones plus about 30 countries on 10M to complete 5B DXCC and 5B WAZ.
> So I mainly deal with IOTA pileups now which are usually on 20 or 15M.)
>
> I gather that a stack of 2 TH7's would be considerably better that the
> single bigger monobanders but I don't think there is room on the
> tilt-over for such an arrangement. Also have considered using a Force
> 12 4BA above the EF420. I assume that the tower would support this
> load.
>
Well, I don't know if an additional 18 feet of tower is going to buy
you much. You might want to model both heights and see what there is to be
gained.
The TH7 is a good antenna but is down 2-3 dB to the Force 12 420 (my
estimate based on our field testing of the TH7 and published figures of the
420). You get into a mechanical problem (I think) by trying to stack the 15M
delta loop over the 20M with adequate spacing. I'd go for either the
monobander by itself on the 68 foot tower or put a Magnum Force 410/415 over
it - that's a real nice small stack (the 10/15 is only 5.6 sq.ft and 36
pounds). The 420 at 68 feet might give you enough advantage in height and gain
over the TH7 on 20 to make it worthwhile. Go for it. Actually I'd put both
towers and configurations up - you can never have too many antennas!
I don't know if a stack of TH7's would work very well on your 68 foot
tower. I suspect not. Put that in your antenna modeling program too.
Cheers, Steve K7LXC
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