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twin turn loop on LAA+ and experimenting weekend.


Kev Haworth
 

That's my four days of trekking around the UK done, Curry, Biscuits and Washing Powder all delivered to Regional Delivery Centres. 

Time for some antenna play! Before I pass out the £40 or so on some 8mm x 6M Cupro Nickel, I'd like to ask what effect a twin turn loop would have on receive only?

The experiment part of the weekend is to turn my loop into a cardioid, resistors are here, ground rod being picked up tomorrow morning. Hopefully I'll be able to hear across the pond a bit easier this time tomorrow evening.

I've also a 1:1 current balun to wind to sit in front of the SDR to 'try' and reduce any noise that is coming in, it'll be useful for when I start to transmit again in the near future.

I bought some Tripp Lite USB cables and they have helped quite a bit with noise from Raspberry Pi getting into SDRPlay RSPDX...

The struggle continues, have a great (and safe) weekend folks.


Kev Haworth
 

Just found Wolseley.co.uk do a 3/8 (9mm) refrigeration pipe for £16 retail... That's a game changer.. Still be interested on your thoughts on what a twin turn loop would achieve over a single turn..


Simon
 

Hi

Was about to say use air con tube!! More maluable..better quality copper and cheaper

I use single and twin turn mag loops for trx.
The twin turn is for 160-80m..only reason its a twin turn is to keep the size sensible..no way i can get a 7m dia loop up in my tiny back yarden in east london. A single loop would rx better ( larger capture area..( tried both on a 40m trx loop.single turn tx same rx better.)
Also for rx only small non cardiod active loops the idea is to keep inductance low..a twin turn will more than double the inductance without increasing the capture area..so a no go..

Parallel crossed loops do work though..but as of yet i have not worked out/ tried converting one to cardiod..if it can be done then they would be a winner..( where to fit the resistor is the issue.)

The 2m cardioid loop does work well ( but its still not a 150m beverage) but i had to alter the input transformer on my preamps..
On mine i used a 16:1....9:1 on ccw
73 core is good..though 43 works but drops efficiency down low. If using ccw preamp then its just a case of rewinding the little transformer on the input..easy..

So in short..dont bother with twin loop for rx.

Simon


Kev Haworth
 

Simon..

Brilliant, thank you for the detailed and easy to understand reply, perfect.

Cardioid is built and receiving on 60M, don't know how directional it will be at that Freq. I've pointed it west to see how VOCM compares to the spanish monster, It is working well as it can tame 252 from 30 over to S9 or less..

I'm struggling with the wind here tonight(!) there must be a loose connection somewhere as the noise floor is all over the place. 


Simon
 

Hi Kev

Glad to have helped..

Question..when u say its tamed 252 from 9+30 to less than 9..what do you mean??

I may be missing something here..
At my qth with the cardioid loops broadside with switchable directions..nw or se

I get 2 completely different stations if i switch from nw to se..both s9 but nw station a . Se station b..

Or was it a typo??

Simon ( not really a lw or mw dx hunter, so lacks info..)

Thanks..


Kev Haworth
 

Simon.
If i 'Beam' directly to 252 , it is massive, 30 db over easily on the s meter. go 90 degrees against it and the cardioid drops it to s9,

I'm seeing lots of 'sproggies' spururious  on the cardioid though. back to a 'standard' loop i think..


Simon
 

Hi

Not sure if we on same page here..

I thought u we’re talking about 252khz..
Using cardioid’s on there nw or se gives me rte ireland or algeria radio..( depends upon which way loops are switched.) but i now think you were talking degrees..opps.

Now on 590khz..usb..( so as to remove lsb .) se direction no vocm..nw s9 or so vocm no splatter..

Remember cardioid loop has much lower angle of radiation compared to standard loop but does not have the 90 degree deep null..but with 2 and a steerer that i hope will be available..watch this space..

Pic of steerer being made..not finished yet..Will not be so untidy!!



The idea of the null steerer ( Chris pointed me at this.) is to allow the general direction of the broadside cardioid loops to be facing nw or se ( as mine are,) but to allow the null to be steerable around the loops..
How much/ large / size degrees steerable is to be seen..but in theory it should be alot..one hopes to be able to steer the null to 90 degrees to direction of loop..
Not tried this before..so learning..only used null steerer/ phaser to cancel noise on antennas..
rather alot of effort in making this null steerer though..( hand making pcb’s etc.) so i do hope it works!!if it does not then no great lose as it will make a good noise canceller..

Testing as soon as the Po decide to deliver some well late relays!!

Simon