My New Antenna Situation.

Started by gil, May 07, 2016, 02:01:12 PM

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gil

Well Bob, I got a balun kit from Sotabeams. However I found out that single core baluns are not good at reducing common mode current. The full core Guanella is supposedly much better...

Gil

gil



gil

#18
Do not cross the beams!
I hope I wired this thing right..
I don't even have a 200 Ohm resistor to test it, my junk box was on the boat..

Oh yeah, and I've been busy:

  • Two EARCHI 9:1 UNUNs.
  • One Sotabeams 4:1 BALUN kit.
  • Guanella 4:1 BALUN.
I'm back!

Gil.

cockpitbob

It's good to see you sniffing flux fumes again.  Nice looking work.
For the 9:1 ununs, are you going to let the feedline be the counterpoise?  I usually put a banana binding post beside the BNC so I can attach a separate wire.  Often my feedline is only 10' or 15' for end feds.

gil

QuoteFor the 9:1 ununs, are you going to let the feedline be the counterpoise?

Yes, but then I use 10m of RG-174 coax... It's long enough to act as a counterpoise and short enough not to be too lossy on HF. I do have a bunch of small ferrite beads to slip on the coax near the radio, but I'd like to make a choke in a thin PVC tube with a BNC on each end..

Gil.

Rescue9

Any update on this I'm very interested in seeing your choke. I'm going to try the 9:1 unun design myself with the new radio to see performance, but am worried about not having a counterpoise since I only plan on having about 25 ft of rg174 as a feed line.

gil

Sort of... BTW your 25ft of coax should do fine in my experience. You might benefit from slipping a couple dozen small ferrite beads on the coax near the radio but I would try without first. Whether you get RF on the radio will probably depend on wire length, you might have to experiment a bit.

I have all the parts now, got a small plastic container for the BALUN. I just need a fishing weight and line to shoot the cable over the big pine tree in my backyard. I tried a stone by hand and it worked for my end-fed, but I need to shoot a wire a bit further out for the Windom.

Gil.

Rescue9

Pics of that small container choke balun when you get a chance please.

cockpitbob

I agree with Gil.  A 25ft counterpoise will be fine.  The coax with some beads near the radio should work well.

gil

#25
The only time I had trouble with RF was using a random wire and counterpoise directly off my K1; feels like needles on your finger tips, very unpleasant. It also usually messes up with keyer chips...

The Windom is built, not deployed yet but I got to test it outside, albeit only three feet off the ground. I had made the long leg of the antenna a few feet longer than calculated, but I don't remember by how much. I get very low SWR, maybe 1.2:1 1.4:1 on 80 and 40m. 20 and 15m show a high SWR, more than 3:1 anyway. This antenna should work on 20m... I hope I didn't mis-wire the BALUN. I could test it with a 200 Ohm resistor but have yet to find one. Adding a few feet of wire will probably lower the SWR further.

There you go Rescue9  ;)

BTW I think I will fill the two EARCHI UNUNs with epoxy resin...

Gil.

Rescue9

Thanks gil. Pics look great¡

Lamewolf

Quote from: gil on June 24, 2016, 03:14:32 PM
Do not cross the beams!
I hope I wired this thing right..
I don't even have a 200 Ohm resistor to test it, my junk box was on the boat..

Oh yeah, and I've been busy:

  • Two EARCHI 9:1 UNUNs.
  • One Sotabeams 4:1 BALUN kit.
  • Guanella 4:1 BALUN.
I'm back!

Gil.

Gil,

After re reading this thread I decided to make one of the "EARCHI" 9:1 ununs to try on my 88' sloper.  Remember I had a 4:1 unun on it that also had a 1:1 choke on it.  The 9:1 unun with the 88' end fed sloper has a much lower swr on all bands than the 4:1/1:1 combo did so I will be leaving it in place for a while to see how it works on the air.  Its only 2:1 on 160 meters !

kc8aon

gil

Great! The EARCHI guy told me yhe maximum length of wire was 60ft, but I think he was just quoting their documentation. One great wire length is 71ft, then 84ft, like the W3EDP which has a 17ft counterpoise, directly into the tuner..

Gil

Lamewolf

Quote from: gil on July 30, 2016, 12:26:30 PM
Great! The EARCHI guy told me yhe maximum length of wire was 60ft, but I think he was just quoting their documentation. One great wire length is 71ft, then 84ft, like the W3EDP which has a 17ft counterpoise, directly into the tuner..

Gil

Don't know why they would limit it to 60' as there are several lengths recommended for use with a 9:1 unun.  Take a look at the chart here: http://www.thedxshop.com/media/wysiwyg/Wire_Lengths_for_9-1_ununs_1.pdf