• Please be sure to read the rules and adhere to them. Some banned members have complained that they are not spammers. But they spammed us. Some even tried to redirect our members to other forums. Duh. Be smart. Read the rules and adhere to them and we will all get along just fine. Cheers. :beer: Link to the rules: https://www.forumsforums.com/threads/forum-rules-info.2974/

Tape measure beam

MNwr786

Active member
5 elements on 2 meter and 10 elements on FRM/GMRS for direction finding. This was definitely not a $20 half-hour project like other tape measure beams on youtube. I'm $105 and 2 days into this and still need to do the feed points/matching, balun, diplexer and switchable attenuator. My first problem came when the 4-way PVC adapters had an internal shoulder and a few elements would be too close for the entire adapter. You think i could find a 1 1/16 drill bit in town? Nope. Had to find an old socket that fit snug and cut teeth into it to ream them out. Then, getting the 2m/FRS spaced so none overlapped led me to chop off the 4-way ends that fit over the pipe. Next came the custom grinding to make the 2m tapes lay flat across the 4-ways. The need for precision spacing led to the expensive purchase of lotsa hose clamps to use as guides when gluing. I ended up using super33 electrical tape to attach the elements and making that permanent with PVC cement made a nice mess on the deck. Anyhow, the hard part is over and now I get to pull out the VNA and tune this bad boy up. One more day and I should have an indestructable portable direction finding beam. Been quite the project!
IMG_20201204_160415561_HDR.jpg
 

road squawker

Active member
GOLD Site Supporter
Wow!!!!
turned into quite the project.

Looks good construction wise
let us know hoe it tunes up on the band(s).
 

MNwr786

Active member
I have not got back to the beam yet, although I did look into the diplexer a bit regarding component values. I need to find a metal project box for it. Hoping to get back to it tomorrow. Ill post a shot of the results on the NanoVNA when I get it done.
 

kc3tec

Member
I built one ( 2 meter/ 70 cm) using gas welding rods about 3 years ago
( Copper coated steel) for elements and an aluminum beam.( tinned solder points with alumaweld rods. The kind you use with a propane torch.( this allows you to use rosin core solder to join the copper to aluminum)
And painted the rig 3 times in clear coat
Gamma match for tuning.
Set it up for a wheelchair bound friend.
He made a rotator out of an old lawn tractor transmission that he operated by hand.
Looked crazy as hell but worked great.
Hes still using the rig.
 
Top