[TowerTalk] Metal Roof

Gilbert Kauffmann k3cc at verizon.net
Thu Jan 11 13:29:29 EST 2018

Tnx Grant,   My repeater is desensed....Folks from 30 to 40 miles are not heard....  Xmit seems ok but the pattern is off.... The tower is on the East side of the house...
the xmit favors the East side as if reflects off the roof......
I've done some experimenting with my moble HF rig.... I must be over 100ft from the house to have (what seems like reflection)   over 200 ft best on the swam part
of my property....I would like to keep at least 200 ft between towers....I have no trees on 16 acres  flat land  with 190 deg + view.....
I also have an 80 meter four square to install.....I'm getting interested in contesting again at 70, I do get tired...  I'll have 3 stations setup
when its ready....  tnx  de Skip  K3CC

-----Original Message-----
From: Grant Saviers <grants2 at pacbell.net>
To: Gilbert Kauffmann <k3cc at verizon.net>; towertalk <towertalk at contesting.com>
Sent: Thu, Jan 11, 2018 9:26 am
Subject: Re: [TowerTalk] Metal Roof

What does "interferes with the 2 meter repeater" mean?

We could get in the ballpark SWR curves to prove an A4S tribander was 
assembled correctly for FD at about 60' out and 42' up from a 56 x 70 x 
14' all metal building. That doesn't say much about the pattern, 
'tho. I think a couple of wavelengths is a good goal. My 40m Moxon 
seems to perform as modeled F/B at 91' up and 70' out from the same 
building, SWR is perfect to modeling. A 4L SteppIR at 40' out and 
91' up from same building works very well (F/B, swr) 20 > 6m.

A 40' 3" irrigation pipe 80m top loaded vertical I had on a galvanized 
metal barn roof peak was awesome at 1550' above a prior Silicon Valley 
QTH. Wind to 80mph. Something you might consider for 80/160.

It is possible to model large conducting plates near antennas or as 
ground planes, but it is a lot of work and requires NEC4 IMO.

Grant KZ1W

on 1/11/2018 8:19 AM, Gilbert Kauffmann wrote:
> I live on top of Niles Hill about 2,300 ASL and the winds is unbelievable high...
> I lost part of my shingle roof twice and the insurance company dropped me.....
> Now, I have a metal roof, fantastic, no problem with 60 mph winds.....
> However, I have a 40 ft tower with a 2 meter repeater antenna.....It seems that the metal
> roof interferes with the 2 meter repeater.... Also, my 160 meter OCF pattern has changed
> a bit toward Northeast....
> As a summer project I have help to erect 2 towers 40 and 50 ft, If more time 89 ft Self support....
> antennas, M2 3 el 40 yagi....Mosley TA34XL,......2 stacked 105CAS....M2 6M7JHC
> Does anyone know how to figure how far the towers should be away from the house ?? It seems
> the metal roof 80 ft long has some interference of 2 meter and my OCF dipole....
> Tnx de Skip K3CC
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