Ted,
Most common problem I've had with the R-7 which gave me inexplicable SWR
changes after working perfectly is when the R-7 slips down onto the
supporting mast. Depending on the size of mast it is mounted on, the
locking bolts can work loose in the wind and the mast gradually slips up
into the R-7 base and it will either rest against the radiator or, touch
whenever the wind blows which is a real drag to find. I spent many an hour
going up on the roof (my R-7 in Moscow was on top of my apartment building
at 200') checking out my R-7 to find it working perfectly, only to be
plagued with the mysterious SWR shift a little later. My first problem was
the intermittent, wind variety.
After I discovered the problem, I put a golf ball (yep, had a golf ball in
Moscow) into the bottom of the R-7 before mounting it on the mast. Fits
perfectly and serves as a preventor to mast slippage. I've used R-7's all
over the world and they work quite well, especially if you can get them up
high and clear. (33' works OK, 70' works great!)
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|