Search found 270 matches

by Andrew (grayhat)
Mon Jun 05, 2023 2:59 pm
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

also, since you have two 9:1 ready, and since you seem to have some room, if you want, pick a lenght of insulated wire and lay this antenna down

http://www.kk5jy.net/LoG/

and I mean LITERALLY down on the ground :D
by Andrew (grayhat)
Sun Jun 04, 2023 7:50 pm
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

You're welcome

If you can and want, please come back with some feedback after you'll have tested the SULA for a bit, it will be welcome and useful !
by Andrew (grayhat)
Sun Jun 04, 2023 8:08 am
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

Nope, I wrote it, the 73 is ok for lower frequencies, as for aiming the loop, I'll repear, the SULA is a directional antenna, so yes, you'll want to aim it at the desired signal
by Andrew (grayhat)
Sat Jun 03, 2023 7:27 am
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

As for the noise direction, I think the noise comes from different sources, regarding aiming the antenna, the SULA is directional, so it needs to be aimed, and then I suggest adding a preamp at the antenna Regarding the transformer, the turns ratio is the square root of the transformation ratio, so ...
by Andrew (grayhat)
Fri Jun 02, 2023 6:05 am
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

the sula size, resistor and height have been optimized for the "diamond" shape, so changing shape or size will require remodeling and optimizing the antenna, that said, yes, try raising the resistor value and also lay the coax so that the section coming down from feedpoint is long about 1 ...
by Andrew (grayhat)
Thu Jun 01, 2023 7:35 am
Forum: General Discussion
Topic: The SULA antenna
Replies: 63
Views: 41335

Re: The SULA antenna

Late to the party :D Ok, here we go, I quickly built a NEC model for a round loop which should be pretty similar to your octagonal, the results of the simulation are below, notice that to recover the cardioid I had to change the resistor value to (around) 642 Ohm, also notice that the horizontal pat...
by Andrew (grayhat)
Sun May 28, 2023 5:54 am
Forum: General Discussion
Topic: Oddity on WWV's 10MHz frequency June 30, 2022 05:10Z
Replies: 11
Views: 9616

Re: Oddity on WWV's 10MHz frequency June 30, 2022 05:10Z

as for cans, I've these https://www.oneodio.com/products/a71-studio-wired-headphones bought them time ago, they were discounted, pretty nice response and good isolation, they're also available on amazon, also notice that if desired, it's possible to buy an additional boom mic for these phones https:...
by Andrew (grayhat)
Thu May 25, 2023 9:30 am
Forum: General Discussion
Topic: Oddity on WWV's 10MHz frequency June 30, 2022 05:10Z
Replies: 11
Views: 9616

Re: Oddity on WWV's 10MHz frequency June 30, 2022 05:10Z

The first thing which popped to my mind was the "Luxembourg effect", but I sincerely doubt it may be the case, although it can't probably be excluded; a secondo cause may be due to some "manteinance" performed on transmitters, in such a case during a tuning/alignment/testing proc...
by Andrew (grayhat)
Tue May 23, 2023 1:51 pm
Forum: Questions & Advice
Topic: Balun for a end fed random wire?
Replies: 5
Views: 5623

Re: Balun for a end fed random wire?

Forgot, the "9:1 transformer" isn't a magical object, the transformation ratio may be appropriate for some antennas but totally unappropriate for others, keep in mind that if the antenna wire is near (or below) 1/4 wave at a given frequency, the impedance will be very low so dividing that ...
by Andrew (grayhat)
Tue May 23, 2023 10:39 am
Forum: Questions & Advice
Topic: Balun for a end fed random wire?
Replies: 5
Views: 5623

Re: Balun for a end fed random wire?

Regarding the impedance transformer, an easy to build one is shown here http://www.kk5jy.net/LoG/ http://www.kk5jy.net/LoG/images/transformer-schematic.png http://www.kk5jy.net/LoG/images/thin-transformer-inside.jpg it's a "galvanic transformer" (that is, the antenna is electrically isolat...