Need help vertical multi-band

[binrat]

I just picked up a used multi-band vertical.
This is what I know:
1. Same mounting on the mast as the Cushcraft R7;
2. 7 traps total, marking are like "TU","TY";
3. 23.5' length of driven portion;
4. only 1 set of horizontal radials closer to the top.

Any ideas as to what the antenna is??

 

[RickC.]

Photo?

 

[binrat]

Photos, bare with me here, first time for this forum.
Starting from the bottom and going up. There is approx 7' between the feed point and the first trap. Only 1 set of horizontal's that are 23" long.

 

[W5LZ]

If it's an 'R-7' then it's a Cushcraft 10 through 40 meter vertical. Those 'traps' certainly look like an 'R-7's. Those 'radials' at the bottom of the thing aren't ground radials at all. They are a 'line isolator' instead (straight from the manufacturer's ad). There should also be a black box about 6 x 8 x 3 inches at the base of the thing. That box contains a torroidial impedance matching network. It connects across a fiberglass insulator. If all that isn't there, you don't have all of that antenna, and it isn't going to work well anywhere.
The two biggest problem areas with that antenna are the impedance matching circuits and that fiberglass base insulator. Both will deteriorate over time and be a real PITA to correct. Cushcraft doesn't have anymore of those fiberglass insulators.
I used one for several years before things 'broke'. I do not plan to ever have another one. Can't say it didn't do exactly as claimed, but it just wasn't worth it for me.
- 'Doc

 

[binrat]

Doc thanks,
The top picture has the feed point with a SO239 on the bottom of it.

 

[W5LZ]

I saw, and wondered about that. But I have no idea if the seller modified the thing or not. Or, if it's something else all together. If that's how it came from the manufacturer then it isn't an Cushcraft 'R-7'. I can't remember ever seeing the same type 'traps' used by any other manufacturer, and that's why I thought it was an 'R-7'. So evidently, it's something I don't know anything about. It would be interesting to hear what happens if you get the thing back together correctly.
- 'Doc

 

[wavrider]

http://tinymicros.com/mediawiki/images/f/ff/Cushcraft_R7.pdf

Link to online manual for the vertical.

 

[binrat]

thanks.
My plan is to clean the jionts that were taken apart, put it up on about 12' of pipe and hook up the trusty MFJ-259B to see what's what.

 

[olegtf]

AP8A
http://www.scootworks.net/dave/hamradio/manuals/ap8a.pdf

 

[BJ radionut]

Looks like it could be and old R6 or R5 Cushcraft...missing the input coil that sits on top of where the SO239 mounts....
Check the MFJ/Cushcraft website under product support...you'll find manuals for both those old designs.
You'll first have to ID the antenna then check every part to see if it's all in proper set-up...only then will you find the "sweet spots" on each band where it will load without using the tuner...to make it work at all you will need the complete radial kit and matching transformer...otherwise it's a "metal stick"
GL
All the Best
BJ

OLEGTF: Looks like you nailed it with the manual....binrat: NOTE the use of additional radials even when mounted on roof or poles to give proper performance

 

[olegtf]

Looks like it could be and old R6 or R5 Cushcraft...missing the input coil that sits on top of where the SO239 mounts....
Check the MFJ/Cushcraft website under product support...you'll find manuals for both those old designs.
You'll first have to ID the antenna then check every part to see if it's all in proper set-up...only then will you find the "sweet spots" on each band where it will load without using the tuner...to make it work at all you will need the complete radial kit and matching transformer...otherwise it's a "metal stick"
GL
All the Best
BJ

OLEGTF: Looks like you nailed it with the manual....binrat: NOTE the use of additional radials even when mounted on roof or poles to give proper performance

I still use it mounted on 7' black iron pipe pounded into the ground, and grounded to the mount, without radials, haven't had a problem yet. SWR next to perfect, as for efficiency, 40m outperforms, else - mediocre. Coax buried into the ground, thus no need for any baluns, or RF chokes on the sheath. Henry 2k8 and no RFI, TVI or upset neighbours. Had a pic, but couldn't find it.

 

[binrat]

Nice, I haven't had time to bolt it together yet. I'm starting a months holidays shortly so it on my list of things to do.