shakespeare 3 element beam

[km6ab]

Update,
Got the 3 element assembled with stock matching harness grounded to the mast per instructions and it has a good match over the CB band, however its got a lot of common mode current on the coax. If you run your hand up and down the coax near the antenna the match changes some.

I replaced the stock matching harness crap with an off the shelf SO-239 to wire adapter with integral 1:1 ferrite balun then played around with a hairpin match, which simply shorts out the feed point with a loop of wire the appropriate size.

The hairpin loop size is not very critical and around 2ft of #12 copper wire bent into a long thin loop about 1ft long and 2" wide across the feedpoint matched it perfectly. The driven element closely nestled between the reflector and director is probably in the 20 to 30 ohm range and the hairpin will help match it to 50 ohm coax. With the ferrite 1:1 balun there is no more SWR changes when you move the coax around and the match is under 1.5:1 between about 26.9 and 27.5MHz.

I think anyone with one of these antennas should scrap the supplied matching harness and use a hairpin match and 1:1 choke balun.

Next I'll trim it down for 10m amateur use.

 

[sunfireman]

Bump.. Any More info or recent photos or scans of manuals would be nice.
Just got the Shakespeare PolarBeam with no Matching stubs thinking about doing the hairpin match on both the vert and horz elements with a balun on each.
Would a 1:1 voltage balun work?

 

[Captain Kilowatt]

You really want a current balun for feeding a yagi.

 

[sunfireman]

Thanks Captain, was not to sure what to feed the yagi with I do have some voltage balun's on hand but guess I should make a trip to the ham store and get a current balun or make one.

 

[SIX-SHOOTER]

I was given BOTH the Three & Four element beams today still in the shipping tubes from Shakespeare but I have no idea how to upload the manuals but I do have them both.I will eventually put the Four element up here & I will sell the 3 element locally.I'm sure few have ever heard of or seen one so that will make them even more interested.I know its an old thread but thought I'd add this reply in case anyone was interested. These antennas are NOS.

SIX-SHOOTER

 

[Gino Laflamme]

Hi,
First time on a post. I have 2 4104 (4 element yagi) but can't find any info. There are treads attach in this post (higher in the post) but seem to be no longer there, Is there someone who has the original doc.

Thanks
73

 

[Gino Laflamme]

Bump.. Any More info or recent photos or scans of manuals would be nice.
Just got the Shakespeare PolarBeam with no Matching stubs thinking about doing the hairpin match on both the vert and horz elements with a balun on each.
Would a 1:1 voltage balun work?

Did you every get an answer for your info on your shakespeare beam ? 73

 

[sunfireman]

Yes I did this is from KM6IB
Without the factory matching cables the driven elements on the Shakespeare Yagi's are simply a dipole insulated in fiberglass and perfect for a hairpin match. The impedance of the dipole will be lower than 50 ohms due to the close proximity of the reflector and other elements and the hairpin will raise the dipole impedance. You should also have an RF choke right at the feedpoint because the coax can unbalance the system and put RF on the coax.

I used about 25 ferrite beads, #43 mix over some RG-142 coax that connects to the feedpoint and that is a basic choke that will calm down most stray RF on the coax. You can also buy an appropriate 1:1 choke balun and connect to the feedpoint.

The final size of my hairpin is a U shaped loop 14" long and 2" across. I made it from 1/8" X 3/4" aluminum flat stock because it was wide enough to drill 3/8" holes in the ends and they go over the whip mounting holes and the whips hold the hairpin in.

I would start with a similar size piece of #12 or #14 bare copper house wire bent to the same rough dimemsions as mine but maybe 2ft long. Check the match first with a 1:1 choke balun and no hairpin attached for a sanity check to see how bad it is, then attach the hairpin loop to the driven elements, which should also be the feedpoint of the coax.

Basically keep whatever width the hairpin turns out to be for a good mechanical fit, then trim off a few inches and check the match. There will be a broad range where the match is good to great and use whatever lengthgives you the best match. You can then make a hairpin out of aluminum like I did or just leave the copper wire on if that works for you. The hairpin material or thickness will not limit the power of the antenna since little power is wasted there.

Good luck and let me know if you need more info or pics. Not sure how I would post pics here.

 

[SIX-SHOOTER]

Hi,
First time on a post. I have 2 4104 (4 element yagi) but can't find any info. There are treads attach in this post (higher in the post) but seem to be no longer there, Is there someone who has the original doc.

Thanks
73

I have the three & four element beams NOS with the documentation but I have no idea how to post it here since I don't have a scanner? I have some pictures of the MegaBeam 4104 paper work but it keeps telling me the file is to large & I'm not a tech & I am a low tech red neck.Somebody want them send me a private message with your email address & I'll send the pictures to you.I have the three element instructions as well but I would need to get them out of the shipping tube & take some pictures of them.

SIX-SHOOTER