After settling with FT-857 as my main SOTA rig, I was thinking what to do with my trusty TM-V71 VHF/UHF FM only radio. I live in an apartament block with no balcony or any other means to put an outdoor aerial, so home use was not apparent at all. To complicate things even more, windows here are ‘Low-emission (Low-E) glass’ which severely blocks VHF freqs and up.
My past experiments with all variants of 1/4s never really worked satisfactionary. Nevertheless, I’ve decided to give it a go and try something again. I’ve opted for a vertical dipole first. Some wire cut to size and sello taped to a plastic window frame. To get decent SWR on 2m dipole size had to be cut more than I was expected for the band, but that worked, I’ve started to reliably receive our local repeater with S7-9 !
Next, looking if things can be improved further I’ve untaped the dipole and quickly taped in a traditional Slim Jim variant made of 0.9mm tinned copper wire. Due to indoor settings and some metal around and inside of the window frame traditional Slim Jim size had to be slightly reduced again. I’ve got SWR 1.5 and the repeater started to come solid S9 though!
While fine tuning the SWR I’ve messed up with wire size and had to take the Slim Jim down just to redo it again.
For experiment sake I’ve purposedly put my next version with much more length, planning to find where the best SWR resides within 100-150MHz range while cutting away and getting closer to a traditional Slim Jim sizing.
To my surprize, the best SWR for my indoor Slim Jim version has come to 1.0 at the below measurements. Well, I know a dummy load would show the same result, so next comes the testing.
The repeater sigs came to great S9+10db, moreover I’ve started to hear Sunday’s IRTS News reader EI6K 25km away. Next, I’ve started to hear 144.825 Internet gateway few km further. The best test, however, was SOTA chasing of my local summits where I’ve successfully made few 5-20km QSOs.
Naturally, I won’t get much further than 20-30km, but having it indoors, in literally a Faraday box is fairly inspiring.
To finalize, I’ve tried to compare to a traditionally sized Slim Jim in the same settings. Suprisingly, on a traditional version I couldn’t hear much apart of my local repeater.
It is by no means a proper test as indoor settings are interfere with everything, but at least I can now chase my local summits at home 
Maybe our antenna experts can aproximate what on Earth did I get with those sizes?
