new antenna - what should I do?

[N3DRB The Derb]

Question for the AM forum brain trust:

my "temp" antenna that the AM mafia put up for me blew down in that huge storm we had a few days ago. I have a W7FG dipole ready to go, but I'm wondering if there's other configs I could use in combo with the other antenna which is undamaged, like a lazy H or a turnstile that might be helpful.

I want a cloud burner out to about 300-350 miles, after that, don't care.

[ka3zlr]

3 to 500, put up a Loop Tim....

[WQ9E]

I use a full wave (cut for 75) horizontal loop for most of my vintage activities.  On the list of things to do is running some low loss coax to the "barn shack" so that I can also use the Hy Tower from the vintage gear positions in the house but the loop works very well on 75 and 40.  I use a homebuilt reversible L tuner with the loop and feed it with 50 ohm coax.  For 160 I short the coax at the feed end and feed it as a top loaded vertical, seems to work OK.  My homebrew tuner uses a very large Gates roller inductor, a 1500 pf vacuum variable, and one of the BC-375 "tap switches" to reverse the L.  It has handled the output of my Desk KW, Viking 500, and Drake TR7-A/L-7 (for 160) for several years without complaint.  The L network also makes a nice lowpass filter in case any of the gear has harmonic issues.

Rodger WQ9E

[AF9J]

Yup Tim,

Rodger & Jack are right.  A full wave horizontal loop  (or if you don;t have the space, a half wave will do in a pinch) up about 30-40 feet should do the trick.  Also, if you ever do get a hankering to do high band AM (try it, it's blast!), the loop will tune pretty well on the higher bands.  If you don't have the space for a loop, putting up your W7FG dipole at 30-40 ft. will also work (it just won't be quite as quiet as a loop can be for receiving).

73,
Ellen - AF9J

[Steve - WB3HUZ]

I want a cloud burner out to about 300-350 miles, after that, don't care.

I don't think you could do much better than what you up before the recent wind storm.

[WD8BIL]

UHHH (knock on the head)...... Helllooo !!!!

With the siganiganal you were puttin' into 8 land barefoot I'm surprised you're axing this question Timmy ! 

Use the same antenna... jest build it better and stronger with a bit more flexibility. Maybe use some heavy bungee cords or pullies and weights for stress relief. But for ether sakes.... Don't  change the basic design.

[Steve - WB3HUZ]

Think McFly!

[N3DRB The Derb]

yeah I guess I should, huh?
 


we had a 6 hour power outage today - just came back on 20 minutes ago.

[K1JJ]

Derb,

Yep, the guys are right...  put up a simple open-wire fed dipole as high and flat as possible, in the clear.

I realize you lost a tree limb, so not much you can do about that situation..


Here's a few tips that you may have already employed -  and work well:

Try to support the center of the dipole. This is what gives longevity to installations. The ends are light - the center is really heavy.  Keep the center supported and the ends loose so the trees can sway w/o problems.

Use steel 1/4" aircraft or guy EHS cable to go through the tree limbs.  The EHS will not saw into the tree, whereas the aircraft stuff will after some time. After a few years, sometimes the tree will grow over steel cable. To remedy this, I will sometimes use the steel cable as a permanent anchor with a pulley on the end  - and use a rope to raise and lower the ant through this fixed pulley. 

BTW, you asked about using a loop. This is cutting hairs, but bear with me.   I modeled a full-wave loop at 60'  for 75M vs: a standard flat 1/2 wave dipole. The loop, as expected, has higher angle vertical radiation at 90 degrees straight up, like a cloud burner.... but only by about 1/2 db more gain.  The problem is that the angles between 80-90 degrees are literally useless on 75M - they are simply too high. The angles between 50-70 degrees are what are used most often for 50-300 miles out.  A flat dipole at 60' high peaks at 70 degrees vertical take off - perfect for local work.

I once proved this to myself in the real world. I put up a homebrew aluminum 75M rotary dipole at 190' with another below it at 90' on a single tower. This was a big project.  I phased them 180 degrees out-of-phase producing a ~5 db gain straight up (90 degree cloud burner). I knew it was working well, cuz when I switched it to zero degrees phasing, the DX was 10-15db stronger and the locals dropped way down.  Anyway, after weeks of testing, I found that my reference dipole at 60' high was as loud or sometimes louder for locals than this elaborate 90 degree up cloud burner beam. I proved to myself that angles of 80-90 degrees were not used much for 75M local work and it's damn hard to beat a simple flat dipole at 60' high. (for locals) 


Good luck putting  up your new W7FG antenna, OM.

Later -

T

[k4kyv]

I want a cloud burner out to about 300-350 miles, after that, don't care.

That antenna put out such a strapping signal on 75 that it would be a shame for you not to re-erect it.  I recall the 15 watt signal that was just as strong here as the DX-100 class transmitters from your area, and that stations all up and down the east  coast were giving you similar reports.  I was eagerly waiting for you to get some power into that antenna.

[Todd, KA1KAQ]

Ditto what the others have said. From the first time you fired your station up and several times thereafter, it sounded like you were several hundred watts up here vs. the 10-20 you actually were. Get that system back up, as close to the same height and location as before. Sweet spot or magic touch from the gangstas who erected it, the thing worked and worked well!