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Loggings => Longwave Loggings => Topic started by: ChrisSmolinski on August 23, 2019, 1854 UTC

Title: DXing in the longwave basement one fine August afternoon
Post by: ChrisSmolinski on August 23, 2019, 1854 UTC

AFE822x and the Crossed Parallel Loop antenna, rotated 3 directions to show directivity.

(https://i.imgur.com/9SgMjrg.png)

Title: Re: DXing in the longwave basement one fine August afternoon
Post by: refmo on August 23, 2019, 2311 UTC

That is quite an impressive demonstration of the Crossed Parallel Loop antenna, Chris.
For comparison, I made a similar screenshot using the Wellbrook Loop, model ALA-1530LNP, also using an AFEDRI AFE822X.
I would say the Wellbrook is somewhat less directional, at least down here in the longwave basement.

(https://i.imgur.com/b8DJ9IB.png)

Title: Re: DXing in the longwave basement one fine August afternoon
Post by: jFarley on August 24, 2019, 0023 UTC

Very inspiring, both.  So much so that I actually tuned down there, which is something I rarely do since all I have ever seen down there is a monstrous miasmic mess of man made slop presumably from switching supplies et al which obliterates everything up to about 185 kHz.  Not today, as I was able to pretty much see a waterfall similar to refmo's, which is thrilling to no end. 

Thanks, guys!

This was with a 96" amplified whip, base about 9 ft AGL.

Title: Re: DXing in the longwave basement one fine August afternoon
Post by: ChrisSmolinski on August 24, 2019, 1134 UTC

I was also surprised at the relative lack of RFI down there.  I posted a video in Equipment of WWVB, also showing the directivity of the Crossed Parallel Loop. Turns out it works perfectly fine without a preamp, with the correct receiver, and a good matching transformer. I am using a variant of my Jellyfish transformer, with the turns set up for lower input impedances than normal, which works well.

Title: Re: DXing in the longwave basement one fine August afternoon
Post by: NJQA on August 26, 2019, 0926 UTC

Can you provide a few more details on how you have the loops and transformer connected?  Why did you decide to remove the preamp?  Are you using RG6 feedline?

Title: Re: DXing in the longwave basement one fine August afternoon
Post by: ChrisSmolinski on August 26, 2019, 1225 UTC

Quote from: NJQA on August 26, 2019, 0926 UTC

Can you provide a few more details on how you have the loops and transformer connected?  Why did you decide to remove the preamp?  Are you using RG6 feedline?

I'd have to pull the transformer to measure the turns ratio I am using. It's a special version of the Jellyfish transformer I make: https://www.blackcatsystems.com/rf-products/potted_matching-transformer-unun-balun-beverage-longwire-k9ay-flag-ewe-dipole-antenna-shortwave-ham-radio.html

LZ1AQ has some good info on the crossed parallel loop wiring here http://www.lz1aq.signacor.com/docs/wsml/wideband-active-sm-loop-antenna.htm

You end up with two connection points to the four loops.

The loops are connected to the transformer, the output of which is an F connector, then a run of RG6, most of which is underground, probably 100 or 120 ft total length?

I removed the preamp because it died from water getting in.  Looks like I don't need it anyway.  I'm a fan of passive antennas anyway, less to go wrong or cause mischief.