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New Ham, issues on 20m... (No replies)

3 years ago
dan0h 3 years ago

I'm a result of the Essex Ham online course, many thanks to Pete, as it got me through foundation on the first go, with full marks!

Bit of a long/waffly story this, but I'm at the pulling-hair-out stage... Immediately after passing foundation, I purchased a used (but as good as new) Yaesu FT-2000 from Lamco, with the intention of running FT8 for a while at 10W, giving me some radio entertainment while I study for Intermediate. I have no outdoor space for an antenna, so built myself an indoor dipole in my loft, using Permanoid "Antenna Cable" and 19T of RG58U on a coke-bottle as a crude choke.

As it stands, I have two bands up there, 40m and 20m. The shack is 1st floor, with the FT-2000, Signalink USB, and an MFJ-969 Roller Inductor tuner. Both bands are cut/tuned with an MFJ-269C to 1.1 SWR at the feed-point. For the first few weeks I started racking up some great contacts, couple of hits out in Western Russia, and a USA East coast hit, really pleased with the performance on both bands. But, this is where things started to get kind of odd...

...I decided to add 15m to the mix, so bought another Dipole center, and ran it up into the loft through a wound bottle-choke, and strung it up, running out of space I decided to place it in the middle of the existing 20m. That evening, with the Solar Flux quite high, I started to get a really bad break-up and distortion when Tuning (WSJT-X Tune) into 20m, but in to the dummy-load no problem at all, but the antenna, not good. I can pull the RF power down to 5W, and get it to seemingly tune up ok, but using PSK Reporter I'm not getting seen anywhere, and am getting random weirdness with my PC keyboard (doubling up characters during Tx), and the odd crash of the Signalink interface. Thinking that my extra new 15m might be in some way reacting with the 20m, I go up to the loft and take the 15m down, and disconnect the feeder at both ends, but to no avail, I cannot put any more than 6-8W into 40m now, without masses of distortion and crashes of the Signalink. I've tried replacing the bottle chokes with wound ferrite toroids (12T), re-hashed all my grounds, by-passing the tuner... But now, for whatever reason, 20m won't play ball!

In the mean time, 40m continues to be amazing at 10W, with QSO's all over Europe and into the US quite regularly. I know its a broad ask, but what could I be missing with the 20m band, how has its behaviour changed, when I've reverted everything back to a known good configuration!? The only other thing I can think of, is I did marginally change the shape of the 20m, its a slightly inverted V, with a double back at the ends (to fit in the loft...), so its like an inverted bull-horn shape, so I may go back up there and straighten it a little more, but running it right to the top of the roof line.

Thanks in advance for any advice or suggestions!

- M7ADH / Wallasey, Merseyside.

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