… You can easily make your 2m band portable antenna 70cms dual band .
At the Workington radio club a few weeks ago I showed some of the flowerpot antennas I like using for SOTA and WOTA . the dual band ones are constructed in a plastic tube , like the one below .
I did away with the pipe so you can roll the antenna up easily and managed to get it working on both bands by wrapping 235mm of baking foil round the coax and shrink tubing over it as you’d have seen at Workington . I thought that would have kept that section rigid enough to stop the foil breaking inside when packed away , but with a lot of use I checked today and the tuning was way out on 70cms . 2m is not affected .
The foil had inevitably split .
Wondering what to do and having nothing suitable I rolled 235mm of foil round a bit of transparent syphon tube I found in the garage which was a slack fit over the coax antenna then shrink tubed the foil over it ( I only had the striped earth stuff of that diameter which made it look like a stick of rock ) .
I got a small cable tie and fastened it gently round the antenna in roughly the right place to stop the tube sliding down and loose enough to move it for tuning up . I’d have to decide how to make something permanent later ?
I realised then it did not have to be permanent , all I had to do was tighten the cable tie when it was tuned and amalgamating tape over it to lock it , and just keep the tube separate in my antenna bag and the antenna can be rolled up small . If you are doing 70cms just drop the tube on the antenna and it’ll slip down and stop on the cable tie in the right spot . Plus the same tube can be used to convert any 2m flowerpot .
slide tube down to cable tie .
The tube just slips off the top of the aerial , which can then be fully rolled up .
2m readings
70cms is a bit of a sharp dip but is ideal for 70cms activations on simplex and usable for much of the + repeater shifts .
" Its turned out nice again "
Richard.