20m compact loop antenna recently added

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20m compact loop antenna recently added

Post by Admin on Sun May 21, 2017 8:41 pm

Hi all,
Interesting events this evening. I have been in Spain for a month, so apologize for the lack of activity here. Much to do. The problems in Spain are very different to those in Sweden: the gardner ran the lawnmower over one of the water sprinklers and it rotated 360 degrees. This resulted in the neighbours horse being totally drenched. I went over there, patted and stroked the horse, then gave it some Swedish hard bread and now I have another friend for life :-)

But I brought back my FT101ZD (16kg) and this weekend I wired it up for 12v battery operation. I stuffed it into the compact 20m loop antenna and I was rather surprised at the results: Running 50 Watts CW, the tuning (gimmick) capacitor simply gets a bit warm and the centre-frequency changes by about 40kHz - 50kHz. If I tune the TX 50kHz below centre I can see the VSWR falling from 1.5:1 to 1:1 after about 10 seconds. But there was no smoke, arcing, sparkerlating, corona or other undesirable effects.

Running about 5-Watts average, with peaks of 20 Watts SSB, there is no detuning at all. With the antenna poking out of the apartment window I worked two UK stations and one Netherland station. I did hang a few pairs of socks on the antenna for the benefit of the neighbours. The antenna is about 40m above street level.

Negative effects? Only one. The antenna is about 4m from my TV set the other side of the window. When I key up it switches the TV on, but there is no TVI. No interference with the landline telephone, either. I just had to turn the TV sound down and keep switching it off with the remote.

I developed the balcony antenna in 1996 because I lived in an apartment, but I did have a bit of space on two huge balconies. Here in Märsta I only have a small glassed-in balcony, so the balcony antenna is not practical. But I was surprised at the results and the 5/7 and 5/8 reports I got.

I am presently building a new antenna to take to work with me. The idea is that I will leave the laboratory and drive up a hill then use a 5.4m long telescopic antenna, based on the Balcony Antenna, fitted into a beach umbrella mount. No pruning needed for 14MHz, so I intend to have a daily session from 11AM to 12AM, weekdays, on 14.190Mhz, weather permiting. I have two 12v 12A/H accumulators so I don't flatten the car battery. That gave me 2 hours operating this afternoon, and the batteries were not fully discharged.

I am looking at getting a fibre-glas fishing rod, after Ivan's suggestion, and I thought of fitting a wire to the length of it, then I can coil the rest up at the bottom and make a tapping for different bands, all with one bit of wire. With the fishing rod fibreglass as a coil former, a 2.5m and a 5m rod, then I should be able to work on all bands from 7MHz through to 29MHz, possibly even 3.5Mhz, and without an ATU :-)

I will drop a massage here when I am QRV, so if anyone wants to have a listen for me then it would be appreciated. I will also be on 14.190Mhz at the weekends using the loop antenna.

Very best regards from Harry - SM0VPO

(Thanks to those who tried and couldn't make the QSO. Back on 14.200MHz Sundays from the 24th Sept.)

Posts : 440
Join date : 2012-11-24
Age : 66
Location : Märsta, Sweden

View user profile http://www.sm0vpo.com

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