New project - compact 20m antenna - no HV caps used :-) Good results from my apartment

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Re: New project - compact 20m antenna - no HV caps used :-) Good results from my apartment

Post by Ivan on Tue May 30, 2017 5:45 am

Hi Harry,
no, I do not have Echolink.
I hope there will not be much span on the forum. If that happens, you can always make the rules more rigid.

VBR from Ivan

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Re: New project - compact 20m antenna - no HV caps used :-) Good results from my apartment

Post by Admin on Mon May 29, 2017 4:18 pm

No problems Ivan.
It would be really nice to make contact with you someday and I was hoping that you may have had HF. But not to worry. Do you have Echolink?

Tomorrow I will be on 20m from work with a mobile station. But I will be pushing 50 Watts into a 1/4-wave groundplane antenna. I will see if I can get a photo.

By the way, what do you think of the new rules to allow free guest access? I hated the SPAM situatuion a few years ago, but now I think the problem has been solved with selecting the standing rhino and no SPAM links allowed.

Very best regards from Harry - SM0VPO

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Re: New project - compact 20m antenna - no HV caps used :-) Good results from my apartment

Post by Ivan on Mon May 29, 2017 1:27 pm

Hi Harry,
I feel myself more as a technician. I am not QRV on HF now, sorry.

VBR from Ivan

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Update

Post by Admin on Sun May 28, 2017 7:45 pm

This weekend was interesting. A good friend (ZL1TWA) sent me a couple of those old-fashioned dynamic microphones, and suddenly I get no RF into the MIC of either my FT101ZD (battery powered) or the X1M (also battery powered). No more Electret TRF mics.

The first thing, using battery > radio > antenna I get a rather high background wideband noise. Simply grounding the battery negative cured that.

The second thing, the 20m loop antenna had a span of 90kHz (VSWR = 1.5:1) with 14.175MHz centre frequency (VSWR about 1.15:1). I removed the balun and now the VSWR is 1:1 at from 14.17 to 14.21. VSWR 1.5:1 occurs at 14.11MHz to 14.23MHz (120kHz span). No difference in interference to telephones or TV Very Happy

The third thing is that I went over the road to the park and used a 5.4 metre vertical antenna in a metal umbrella mount. No radials needed to get close to 1:1 VSWR from 14.05MHz to 14.33MHz. I even heard a 5/9 JA station, and a pile-up for a Lebanese station, but my 5-Watts was no match for the "big boys". The propogation was very good yesterday (Saturday).

From my balcony I tried a full 50-Watts CW and the gimick capacitor on the antenna burned. But changing the capacitor to two bits of copper 5x7cm spaced 4cm apart I got resonance at center of band and no smoke using the full output of my FT101ZD.

I will update the project on the homepages with the changes.

But on a more interesting note; I plan to operate on 14.19MHz on Tuesday this week from the car-park at work, weather permitting. Using 50-Watts SSB. If I have the time I will be on every day of the week. If I stay in the department then someone always drags me into a meeting, os pushes a problem up my vest. It the WX is OK then I hope to operate every weekday during the summer, except Thursdays. So if either of you two have an HF rig then perhaps we can hook up on Tuesday? About 11:10 Stockholm time (GMT +2).

Very best regards Harry
@ Ruud - So glad you had a nice birthday. I will reply to your mail shortly but it was very interesting reading.
@ Ivan - Are you still active on HF? I worked RA3 and G4 from the balcony with 5W last week :-)


Last edited by Admin on Sun May 28, 2017 7:50 pm; edited 2 times in total (Reason for editing : seemed like a good idea at the time)

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New project - compact 20m antenna - no HV caps used :-) Good results from my apartment

Post by Admin on Tue Apr 11, 2017 7:30 pm

Hi everyone (and that means all three of you),

This Sunday I was still playing around trying to get a signal out on 20 metres, and I kept looking at my old frame antenna project. Problem is that I have no HV tuning caps, and PCB etching is out of the question (Maj-Lis is here in Sweden with me ;-).

So I wound come wire on some plastic bits, experimented with spacing and made a nice little antenna that does not need any tuning caps. I cab simply poike it out of the balcony window in a brush-handle. On first trial I got a contact in Ukrain with my little 5-Watt X1M. I could also hear L&C Denmark and France.

The project was inspired by others who took my 80 metre frame antenna and modified it for 20 metres, but mainly motivated by having a rig here without any means of using it in the apartment.

Total cost to build was SEK 18 (US$ 1.5) for a strip of block connectors, but only 1/3 of the strip was used. Does that make it a $1/2 antenna?

Anyway, I was surprised by the results. Even better than I though it would be. VSWR is almost perfect at 14.175MHz.

Hope someone out there finds it and puts the project to good use. It took me longer to document it that it took to make it. But it was also a maiden voyage for my GDO-2 in it's first serious application (setting off the theft alarms in H&M is not considered serious ;-)

Very best regards from Harry - SM0VPO

PS - I wonder - how about a multiband loop antenna?

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