2 Element Quad

[HomerBB]

Ok. Brought the antenna down and did it over again.
Made a few adjustments and it affected my SWR positively:

28.755 --------- 1.7:1
28.305 --------- 1.2:1
27.855 --------- 1.2:1
27.405 --------- 1.2:1
26.965 --------- 1.1:1
26.515 --------- 1.0:1
26.065 --------- 1.5:1
25.615 --------- 4.0:1
25.165 --------- 4.0:1

Also got it up a little higher from 27 feet to 35 feet at the boom.
No skip this evening to work it out on, and the locals are all enjoying the great outdoors.

 

[KingCobra]

SWR

Nice SWR's!!!!!!

 

[HomerBB]

Nice SWR's!!!!!!

Oh. yeah. Best I've had from this thing to date.

 

[RickC.]

That looks good!

What'd you end up doing? How does the f/b seem to be?

 

[HomerBB]

That looks good!

What'd you end up doing? How does the f/b seem to be?

This is what it is now as suggested by a hand on another forum:

Recut the match section to a 1/4 wave matching section cut for 27.075:

Frequency: 27.075

wire:Took off the insulated wire in favor of bare #14
Remeasured for
Reflector Wire Length: 38 ft 7 3/8 in
Driven Wire Length: 36 ft 4 21/32 in
Reflector to Driven spacing: 4 ft
Spacers for Reflector: 13 ft 7 13/16 in
Spacers for Driven: 12 ft 10 3/8 in

The b/f is not as tight as I'd like. S-units drop about 2 -4 from straight on the front. I'll use it until my wife calms down, then I'll stealthily modify some more.

Removed the omni antenna that was thirty feet NE of it and the SWR improved from 1.2:1 to 1.1:1 and similar drops across the measure band, except the steep low end freqs went from 4.0:1 to 3.8:1.

 

[HomerBB]

DX Contacts:

5/20/09
333 ----------------------------- Bristol, Tenn.
454 ------------------------------ Virginia
Bigman 47 Tango Charlie -----N Carolina
91 Grease Monkey ------------ S Carolina 27.285
47 ------------------------------- Lake Erie, Ontario, Canada 27.385 lsb
83 ------------------------------- Virginia
340 ------------------------------ SW Virginia
5/21/09
183 ----------------------------- S Carolina 26.755
1269 ---------------------------- Kentucky 26.825
009 ----------------------------- Kentucky 26.825
151 ----------------------------- N Carolina 26.825
Carolina Mobile--------------- N Carolina 26.925
5/22/09
ImaHead ---------------------- Florida 27.285
175 ---------------------------- Georgia 27.225
974 ---------------------------- S Carolina 27.405
Bush Hog --------------------- Jackson, TN 26.835
153 ---------------------------- Jackson, TN 26.835
Barefoot Hillbilly ------------ TN? 27.315
Gentleman Jack ------------- Lynchburg, TN 27.105
218 ---------------------------- Oxford, GA 26.915
747 Slick ---------------------- Coopville, TN 27.345
2Pill---------------------------- Alabama 27.225
726 ---------------------------- N Carolina 27.345
143 Wildman ----------------- SE Tennessee 27.325
Dodge Boy ------------------- Columbia, S Carolina

As an aside:
full wave loop skywire in attic:
Hamburger Man (spreading that mayonnaise) -----Carolina/Georgia line 27.225

 

[CDX-007]

Hey Homer,

Well, I just found this post, sorry I missed it a month or so ago.

Looks to me like your wire length is just a bit too long.

When I built my 3 element Quad I was able to get PHENOMINAL results from it by tuning it to a gnat's eyelash.

If you go back to the standard 75ohm transformer matching system, try wrapping the 75ohm section into a common-mode choke to help attenuate feedline radiation/coupling.

I simply cut my driven too long, then using a carefully cut 1/4 wave 75ohm transformer, cut the driven wire until it showed a flat swr on my chosen center frequency.

I then cut the reflector 6% larger than what I ended up with for driven wire length and began the process of cut-n-spin tuning.

I placed a vehicle several blocks down the street with an SSB rig locked on keydown on USB, and adjusted the carrier balance VR off slightly so I had about a 20-30 milliwatt carrier, giving me just enough signal for tuning.

I pointed it away from the 'beacon', checked the S-meter, then pointed it toward it and rechecked the S-meter.

Cut, recheck, spin 180*, cut, recheck, spin 180* etc...

I was tuning the reflector on ch.20 so I could pass it up enough to notice the slight drop in performance and found it dialed in on ch.34 as center, close enough to ch.37 where I was wanting it flat.

Then I added the director and repeated the painstaking process of cutting, rechecking, spinning, cutting rechecking, etc...

When I was done I had quite a performer.

I won't bore you with the entire story, but Clancey (R.I.P.) had an early '70s Hy-gain Long John 5 element Yagi on a 60' tower and a 150w pep.
I had the 3 element Quad at 52' boom height with an itty-bitty 80w pep amp.

He would often, and typically under the affluence of Inkahol, get belligerent with me regarding this, "POS wire antenna which couldn't work as well as a true horizontal Yagi because it had no elements in the true horizontal plane."


One evening, back in the early '90s, as I spun the dial I heard him in QSO with an Australia station. While he was keyed asking for a signal report I rudely keyed over him and threw out my call: 'Gold Coast 223'. Immediately the Aussie returned with, "Stand-by one, 223".

When Clancey unkeyed he received a good report: S-7 to S-9 with excellent audio, then the Aussie gave me a 20-over-9 report.

That was the last time I heard squat from Clancey about my inferior Quad beam.

 

[HomerBB]

Hey Homer,

Well, I just found this post, sorry I missed it a month or so ago.

Looks to me like your wire length is just a bit too long.

When I built my 3 element Quad I was able to get PHENOMINAL results from it by tuning it to a gnat's eyelash.

If you go back to the standard 75ohm transformer matching system, try wrapping the 75ohm section into a common-mode choke to help attenuate feedline radiation/coupling.

I simply cut my driven too long, then using a carefully cut 1/4 wave 75ohm transformer, cut the driven wire until it showed a flat swr on my chosen center frequency.

I then cut the reflector 6% larger than what I ended up with for driven wire length and began the process of cut-n-spin tuning. . . .

When I was done I had quite a performer. . . .

Your entire post is interesting. I am still working on the antenna in terms of thinking on potential finer finishes to it. So thanks for the info.
This part:

If you go back to the standard 75ohm transformer matching system, try wrapping the 75ohm section into a common-mode choke to help attenuate feedline radiation/coupling.

I've done, except the RF choke is in the 58ohm feedline. Am I correct in hearing you say to move from the feedline to the transformer section?

Also, I believe the guy wires are influencing the radiation pattern. I will be replacing the antenna end of the guys with non-resonant rope.

The antenna can only be tuned by lowering it. The fine tuning process you described is not possible at the working height. I'll have to figure that out.