HFU HF Underground

Loggings => North American Shortwave Pirate => Topic started by: ChrisSmolinski on November 25, 2018, 2155 UTC

Title: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: ChrisSmolinski on November 25, 2018, 2155 UTC
2151 SIO 333 signal (using USB to deal with the UTE on the LSB) using my newly modified 75m dipole which provides the best reception, better than any of my 40m antennas or the sky loop. Which makes no sense at all, but hey, it works.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: Josh on November 27, 2018, 2027 UTC
Please tell us more about this modification.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: digitalmod on November 27, 2018, 2043 UTC
 ;D If you tune out the reactance, it may give directivity and hence some gain.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: ChrisSmolinski on November 27, 2018, 2125 UTC
Please tell us more about this modification.

All I did was make it closer to a horizontal dipole on one leg, vs an inverted vee. The other leg still slopes downward at about a 45 degree angle. I want to fix that, but there's some tree limbs in the way. 

I'm quite surprised there's any signal at all on 6770, as the antenna is resonant at about 3900. It was purely accidental I tried it, I switched the receiver to 6770 before I had the chance to swap antenna inputs.  Mostly likely the antenna has some weird nulls and peaks, and one of the peaks is aimed at OTR (wherever it happens to be located). Or Chuck Norris was wandering through my backyard at the time.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: Radio Station on November 27, 2018, 2313 UTC
I use a complete flattop dipole fed with 450 ohm ladder line. From what I read a flattop has more gain than a sloping or inverted design. You change the pattern of your antenna by bringing the end up.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: ChrisSmolinski on November 28, 2018, 1120 UTC
Speaking of "how can this antenna possibly work", the other day I was out in the yard and noticed the lower support rope for the tilted folded 40m dipole had come lose, and most the lower leg of the dipole was laying on the ground. But I had been using it earlier in the day, with good results. I fixed it, but wondered if that was a mistake  ;D
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: Radio Station on November 28, 2018, 1604 UTC
That's interesting. I have a much lower dipole that I use for noise canceling and signal enhancement with a MFJ-1026. At some frequencies at various times I will get a better signal on the much lower dipole.
Title: Re: OTR 6770 AM 2151 UTC 25 Nov 2018
Post by: Josh on November 28, 2018, 1954 UTC
Interesting, I suspect the sloped part would respond more to vertical and angular polarity, the horizontal portion to horizontal polarity, perhaps the best of all worlds.