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Antenna for SAQ reception with RSP2

Posted: Tue Jun 25, 2019 4:01 pm
by PA0MHE
I hope to receive the SAQ station at 17.2KHz, using my RSP2 High-Z antenna input. So not using the Mini-Whip of PA0RDT.
Has anyone experiments doing this ? What type antenna is used.

Re: Antenna for SAQ reception with RSP2

Posted: Tue Jun 25, 2019 7:34 pm
by g1hbe
For most of my LW/MW and HF listening I use a Wellbrook 1530 loop to help keep the noise down, as wires are very noisy in an urban environment. However, the 1530 falls off below 30 kHz and only just receives SAQ, so I built a similar loop using a plastic hula hoop with a few turns of wire inside and a simple amplifier similar to the PA1m design. I put a large capacitor across the loop to limit its response to below 100 kHz. Result! SAQ is now easy.
Grimeton May 2018.jpg
Grimeton May 2018.jpg (100.68 KiB) Viewed 4229 times

Re: Antenna for SAQ reception with RSP2

Posted: Tue Jun 25, 2019 8:14 pm
by PA0MHE
Thanks for your quick answer.
The good news is that I live on a very rural area with neighbors a mile away.
For the homemade hula hoop you used an preamp, why can this not directly connected to the High-Z differential input from the RSP2 ?
Do you remember how many turn you used for this magnetic antenna ?
Good suggestion for the large cap !

Re: Antenna for SAQ reception with RSP2

Posted: Wed Jun 26, 2019 4:54 am
by sdrom33
Please explain what SAQ is about? Thanks :?:

Re: Antenna for SAQ reception with RSP2

Posted: Wed Jun 26, 2019 6:28 am
by PA0MHE
It a machine transmitter in Sweden on 17.2 KHz
https://alexander.n.se/the-radio-statio ... q/?lang=en

Re: Antenna for SAQ reception with RSP2

Posted: Wed Jun 26, 2019 10:14 am
by g1hbe
PA0MHE. Me again. OK, I've just found a few notes I made when I was building this LF loop. The hula-hoop is about 80cm diameter and there are six turns of wire threaded through the tube. This gives 125 uH and to tune it to 20 kHz took (get this) 470 nanofarads or 0.47 uF. Tweaking this value could land you directly on SAQ, but mine receives it anyway even though it's not bang on the frequency.
Re using it without an amplifier - I've just quickly built an identical loop and connecting the ends to a balanced, twisted feeder and applying the other end of the feeder to the balanced hi-z input of the RSP2 got me signals. About 15dB lower than the version with the amplifier but I'm sure it would be OK.
I'll be taking my loops down for their annual maintenance soon, so I may add an extra cap to see what's even lower down!
Andy.

Re: Antenna for SAQ reception with RSP2

Posted: Sun Jun 30, 2019 9:44 am
by g1hbe
Here is SAQ as received on the loop this morning with my RSP-2. Lots of electrical spikes today, but copy is still good.

Re: Antenna for SAQ reception with RSP2

Posted: Sun Jun 30, 2019 10:28 am
by PA0MHE
Thanks, I also succeeded to receive it magnetically with to your help.