Loop on Ground and SDR

apparently a #73 should work down there

https://toroids.info/BN-73-202.php

The mix of binocular cores is usually optimized for HF or VHF. I have never seen a binocular core designed for 50 - 200 KHz. Toroids, pot cores and EE cores designed for these frequecies are used frequently.

VBR from ivan

well, it could be tried, but a binocular core offers much better performance than a toroidal one in this application

A core from a switching PSU should be perfect for the transformer, the working frequency is similar.

VBR Ivan

no Ivan, just one turn, but it should be a bit longer, then by the way, it will loose performance going up in frequency, also, you will probably need to wind the transformer using a different material

Hi,
did anyone try the LoG on 137 KHz? Maybe it would require several turns?

VBR from Ivan

Andrew wrote:
Well... if you can have someone going up the tree for you and installing a pulley, you'll then be able to easily lower/raise the antenna just using a rope

That is a good idea. In my younger days I installed covert antennas for a disabled radio ham. I am sure than there are people locally that may be able to help me.

BR Harry

As for the LoG signal level, if you can't compensate it using the rig preamp (it usually suffices), you may consider using a simple tuned preamp like this

http://www.arrl.org/files/file/QEX_Next_Issue/Jan-Feb2018/Steber.pdf

in such a case, the preamp will be at the antenna feedpoint, (just at the transformer output) while the tuning control will be in the shack, a run of cheap cat5 (network) cable will then allow to power and tune the preamp

Well... if you can have someone going up the tree for you and installing a pulley, you'll then be able to easily lower/raise the antenna just using a rope

Andrew wrote:Hi there, Harry !

I have helped a friend, yesterday, putting up a "random" wire and we also installed a LoG (the random isn't exactly a quiet antenna in RX), and the combo is really good, plus, wirh 45m of wire he can now cover all bands from 160 to 10 meters, it's a win/win setup

I am still thinking about that and how I can implement it. Me, ladders and trees are not a good combination at the moment. But thanks to your experience I have got a few ideas.

160m? I have never, ever considered that band. To me that band is "bordering on the audio"

BR Harry

Andrew wrote:Hi there, Harry !

Hope your. health will improve soon.

My health is ok for a 70-year old suffering from PV. It is not the illness itself, but all the side effects that are creeping in after 20 years of it.
Also Maj-lis has needed a lot of support in recent months to recover her vision. But she is getting better and as from a week ago she can see much better.

BR Harry

Hi there, Harry !

Hope your. health will improve soon

As for the LoG, yes, it's somewhat picky about installation, but in my own (and yours too) experience it MAKES the difference, in particular in high noise environments, sure, signals are lower, but readable and THAT is the important thing

I have helped a friend, yesterday, putting up a "random" wire and we also installed a LoG (the random isn't exactly a quiet antenna in RX), and the combo is really good, plus, wirh 45m of wire he can now cover all bands from 160 to 10 meters, it's a win/win setup

Hi Andrew,

This weekend I had little time to "play" but I did try a makeshift LoG antenna to prove the principle. I did experiment earlier in the year but I was too busy with illness and household things to do anything serious.

On Saturday, 3.5MHz - the UPS interference was NOT visible. At first I thought it was dead, or not connected. But Saturday evening the band was alive, just like listening to VHF. Absolutely no movement on the S-meter between stations.

Signal strengths were very low, but if I had been in QSO with anyone I would have been giving 5/0 signal reports
- LoG antenna - about 30 QSO's heard
- Dipole (+ATU) - only about 7 or 8 QSOs heard.

As you wrote in the previous thread, this is an excellent receiving antenna. When I have more time I will have it assembled a bit better and properly matched.

One important point I noticed, the LoG experiment was beneath my dipole, and with 100W into the dipole at 7MHz, I could light a torch-bulb (6V 40mA) with the RF from the LoG. Anyone building the LoG will have to be careful with positioning and be aware that there could be enough RF power to stuff a receiver front-end.

By the way, my /P HB mobile antenna on the car with the 2m long telescopic "portable flagpole" works great. We have really low temperatues, around -18ºC, so it is not really practical to do any mobile operating. It will be interesting to just cast a LoG antenna on the ground beside the car and see what the difference is between the TX and the RX antenna.

Very best regards from Harry - SM0VPO

In case someone is curious, a Polish folk decided to set up a public SDR receiver using the "LoG" antenna (http://www.kk5jy.net/LoG/) and, while the antenna setup isn't (yet - hopefully) optimal, it may give an idea about what to expect from such a very simple and stealth receiving antenna for the 160 to 40 (and somewhat the 20) meters band, so, if you're curious, point your browser here

https://so8oo.net/en/websdr/

by the way, if possible, pick the "right" time of day (or night) and check the S/N (it coulf be MUCH improved by properly setting up the LoG, but as is, it's not all that bad)