[Elecraft] CW power output and remote tuners

[Fred Jensen]

On 12/20/2013 8:15 PM, Ron D'Eau Claire wrote:
> 1) A good ground is only important when the length is significantly
> less than 1/2 wavelength.  Otherwise the impedance at the feed point
> will be relatively high, meaning a ground is needed only to keep the
> rig from floating to a problematic RF potential as I explained in my
> first post.

Ron is correct, a half-wave is *nearly* insensitive to "grounding" [i.e. 
radial field].  However, strangely enough, feeding an EFHW, it really 
helps to have a radial hanging off the coax shield at the balun/xfmr at 
the antenna ... about 6in [15cm] long on 20m.  Learned this from EZNEC 
and verified it in the real universe.
>
> 2) You want adequate distance between you and the radiator to comply
> with the FCC RF exposure guidelines. You need spacing at the higher
> frequencies. There are a variety of guidelines for that, but I always
> use 2 meters at 30 MHz. It's less on the lower frequency bands.

Sadly, RF exposure may be the least of your worries if you're close to 
the antenna.  I have a 3" pipe that runs vertically from a 1 ft sq 
utility box in the wall, opens under the desk and in the wall outside in 
the carport, weather head on the top.  It carries all my coax up and to 
the messenger to the tower.  I decided to mount a GAP Titan vertical on 
the pipe just below the weatherhead.  The antenna works great ... as an 
antenna ... but it is 12ft over my head in the shack.

All seems well in the shack on 40 and 30m.  Alas, on 20 and above, at 
500W, everything electronic in the shack either forgets everything it 
ever knew, or goes totally berserk.  Still working on ferrite therapy.

Don't know about the exposure issue [math major, not biomed], but in the 
late 50's/early 60's [late teens/very early 20's] working at the TV 
station to support myself in college, I got $50 twice a year to climb 
the tower [~400ft] and replace the clearance lamps which was an FAA 
requirement.  Station had the gear, they had it inspected twice a year 
by the mfr, they sent me to climbing school at PG&E [power company], I 
climbed inside the tower on a ladder, and had a fall arrester on the 
steel cable down the center.  A work-out to the top, but I was really 
young and it wasn't exactly the most dangerous thing I'd ever do.

I climbed in the middle of the day, TX was on a ridge just off the 
Pacific and the wind was constant and cold.  We were also on the air, 
10KW visual and 10KW aural, and at the top lamps, where the mast started 
up to the turnstile antenna, I would linger a little because I got warm 
for the trip down. :-)  OSHA today would have a major cow.  The station 
hired riggers to service the beacon on top, it had a automatic spare. 
$50 was a lot then, the first check fixed the brakes on my old truck, 
lack of which was probably far more dangerous than the tower. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org
>
> 73 Ron AC7AC