QRV from home now :-)

Really interesting couple of weeks:

1 - Asked my empolyer if I can have Friday off work - EVERY week. "Harry, how can I say NO?".
So now I am on 4-daya a week working :-)

2 - Trying to build a multi-band antenna in a limited space so I used a 1:1-balun to feed several dipoles, and every few days I add a new dipole. The results are VERY interesting.

All antennas centre-fed from the same balun:

Added 14 MHz, 10.3 metres - VSWR=1:1

Added 7.15 MHz 10.3 metres plus base-loading coils
  14 MHz VSWR almost 1:05
  7 MHz VSWR about 1.2 from 7.05 to 7.2MHz

Added 29 MHz
  29 MHz VSWR 1:1.1 from 28.5 to 29.5 MHz
  14 MHz VSWR almost 1:1
  7 MHz VSWR about 1:1.3 from 7.05 to 7.2MHz

Added 27.3 MHz
  29 MHz VSWR 1:1.2 from 28.5 to 29.5 MHz
  27 MHz VSWR 1:1.2 from 26.8 to 27.5 MHz (with HUGE 1:2.5 at 27.8 MHz)
  14 MHz VSWR 1:1.2 from 14.1 to 14.3 MHz
  7 MHz VSWR about 1:1.4 from 7.05 to 7.2MHz

Added 3.5 MHz (with base loading coils)
  29 MHz VSWR 1:1.3 from 28.5 to 29.5 MHz
  27 MHz VSWR 1:1.3 from 26.8 to 27.5 MHz (with HUGE 1:2.5 at 27.8 MHz)
  14 MHz VSWR 1:1.2 from 14.1 to 14.3 MHz
   7 MHz VSWR about 1:1.6 from 7.05 to 7.2MHz
  3.5 MHz VSWR 1:1.3 from 3.65 to 3.8 MHz

So the technique of adding dipoles to a common feed-point works, but there is degradation between the antennas. The 3.7 MHz antenna was almost 1:1.1 when it was alone, but cannot get it better than 1:1.3 now. Also had to reduce the loading coils by a few turns - when added to the rest in combination the centre-frequency fell from 3.75 MHz to 3.31 MHz.

So there is a limit as to how many dipoles one can add in parallel. I have used 8cm spacing between them, but perhaps that is not enough. Next experiment is to use the same feed-point for the 3.7 MHz antenna, but lead the dipole wires in another direction to get more spacing.

It was the 80m band antenna that I really wanted. I am not able to operate during daylight as I have always got so many other things to do. The house is still in a mess after moving two homes into one house. Still a load of boxes, too many sofas, chairs, and other such things.

But at least I can put out a signal. One small experiment to make is to add another temporary mono-band antenna and compare the results with my multi-band experiments.

Anyone else have any experience with HF antennas in a small space?

BR Harry

A year ago I bought a used FT-840 in exchange for one of my two FT-101ZD vintage radios.
The radio spent three months under guarantee for intermittent TX/RX. Before I sent it back under guarantee I had bad audio reports.

With the new antenna this week I tried it on the air and once more really bad audio reports. The problem is NOT audio getting into the mic with the antenna only 7m away: Backing off the RF power level, it sounds sweet and clean if the RF output is 25 Watts or less. Makes no diference if I use an antenna or a dummy load.

This sounds really similar to the effects of one of the two PA transistors defecive. Pernhaps I should have kept the old FT-101ZD?
Modern rigs can have a lot of great features and SW functions, but when all is said and done, a 35 year old rig, with tubes in the final stage, is BUILT, rather than assembled on a production line. I am really lucky to have a second FT-101ZD (the one with the home-made 12v inverter module).

Tomorrow (today?), Wednesday, is our 27th wedding anniversary, but on Thursday the 29th I hope to be on 14.175 MHz (with the FT-101ZD).

I have a little homebrew SSB TX exciter card that I can stuff into the 300 Watt linear. Only have about 500mW from it so I should be able to pack 50 Watts. That will mean about 10 seconds between TX/RX changeover. So if anyone fancies a reeeeaalllllyy  sslloowwwww QSO on Thursday then perhaps have a listen at about 15:00 Swedish time, 14:00 UK/GMT.

Best regards from Harry - SM0VPO

PS - I have new QSL cards - funny ones :-)

Hi all,
Not working this week as Maj-Lis and I are celebrating some events.

I tried a 27/28 MHz mag-mount on the roof but 1.2 metres can be seen easily - antennas are frowned upon. Besides that, mag-mount antennas are designed for mobile use and they are too short by far.

So ... it is back to the back garden.

Vertical 1/4-wave for 14 MHz is not so good, and every time I tried to use it I had to take my radio outside, powered with a car battery   Kinda spoils it somewhat.

Last night I had an idea ...

The vertical 1/4-wave for 14 is made of aluminium tubes. In effect it is a 5.5 metre mast. I changed the 1/4" top section for something a bit thicker, added an extra pit of pipe and I have a 6.5m mast   Now that opens up possibilities.

I put a pulley at the top. Idon't have any pulleys, yet, so I used a carabina ... Added some builders line as guy-ropes ... took some flagpole rope ...


1:1 balun inside a plastic pill-box, three bit os coax from the front bedroom, joined with block connectors and insulkating tape, and I managed to hoist up an inverted-V. The ends of the V are about 1.5m off the ground. So the antenna is clear of bushes, and after two visits with a pair of wire-cutters I got a VSWR of almost 1:1.

So now I am QRV on 14 MHz.
All I need to do is parallel more elements to make it into a multi-band antenna, and all the higher bands will be at the top of the pole, instead of at ground level, surrounded by bushes.

Been listening to this weekends contact, and then worked Vrhnika (Slovenia) and Naples (Italy) with just 20 Watts.

It is great to have the radio working from inside the house   and now I can extend it and improve it all

Tomorrow I will get some 38mm steel tube and make the mast a bit more permanent. I will also splash out and get 50 metres of 50Ω coaxial cable. It will look like a "cage dipole" when I have finished, but I don't know if I will have sufficient space for 3.5MHz. Maybe feed-point or mid-point loading coils?

So that is the news from Vänortsringen in Märsta. Just one last contact B4 I go to bed.


Goodnight all.
Harry - SM0VPO