3 - 30 MHz Choke
#4
The antenna is a FAMPARC multitap vertical mounted on the chook shed about 30m from the shack. This works surprisingly well.

(The EFHW is still under construction - the capacitors arrived today.)

Igor, the EFHW will have a counterpoise, either a 0.05 wavelength wire (at 40m) or I will attach it to a handily located wire fence. I simply don't want the coax to be the counterpoise.

The radio bench has a groundplane under the radio which earths to the shed structure, which in turn, earths to an earth stake. Every chassis earths to this too.

The shield of the feedline joins this earth on entry to the shed. I have tried with and without this.

Every cable in and out of the radio either has clip-on ferrites or is looped through a toroid.

I have built a couple of other chokes that have less common mode attenuation, something in the order of -19 to -25dB across the bands. Unknown ferrite mix bought years ago from **** Smith. I have experimented with these at one end or the other and both. To little avail.

The issue I occasionally see is that during transmit on digital modes on 10 and 15m the PC will drop the connection to the radio. Below this there is no issue. Curiously 12m seems to be less affected.

Now, when I first set up digital stuff at my old QTH in Sydney I did have similar random drop outs. I fixed it by simply moving the laptop further away from the radio. This fix is a little more awkward on the current bench, but not out of the question. In order to test it I need to get a couple of longer USB-C extension cables (this is a different laptop so, of course, new cables are required.

While I will press the new choke into service for the vertical set up as an experiment, I am actually building it and its sister for both ends of the feedline from a G5RV Jnr (and 20m dipole) that I am currently trying to engineer a mounting system for (between and over a couple of sheds - it turns out tin sheds are hard to securely mount stuff to. Not like the old days of a hockey stick pole screwed to a barge board with some coach bolts). Oh and waiting on some replacement SO235s as the cheap ones I got aren't 5/8x24 UNEF, probably M16x1 - that serves me right!

The weather and having to go to work every day is a big limiting factor, as is keeping the orchard presentable!
Colin
Barossa Valley, SAP. PF95ln
(aka VK5CSW)
Reply


Messages In This Thread
3 - 30 MHz Choke - by VK2CSW - 13-07-2024, 11:02 PM
RE: 3 - 30 MHz Choke - by VK4ADC - 16-07-2024, 07:59 AM
RE: 3 - 30 MHz Choke - by VK6ZFG - 16-07-2024, 04:35 PM
RE: 3 - 30 MHz Choke - by VK2CSW - 16-07-2024, 05:33 PM
RE: 3 - 30 MHz Choke - by VK6ZFG - 16-07-2024, 06:25 PM
RE: 3 - 30 MHz Choke - by VK2CSW - 16-07-2024, 06:42 PM
RE: 3 - 30 MHz Choke - by VK4ADC - 16-07-2024, 08:56 PM

Forum Jump:


Users browsing this thread: 3 Guest(s)