Best antenna no good signals?

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k9zip
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Best antenna no good signals?

Postby k9zip » Tue Jun 04, 2019 12:48 am

I can't seem to get any signals on my new SdRPLAY 1A. Any thoughts on a simple antenna? I have a 33 foot long wire plugged into the box using a banana plug into a so259 but can even receive any AM or FM broadcast stations. I had a dual band mag mount and that seemed to work for while but not on HF frequencies..

Thanks

N2HAM
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ON5HB
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Re: Best antenna no good signals?

Postby ON5HB » Tue Jun 04, 2019 8:35 am

An antenna depends on the frequencies you want to receive.
There is no simple solution to receive all bands.

For HF it means a very long wire and some counter point, then it will work.

You may want to read this, it will get you going:

https://www.sdrplay.com/wp-content/uplo ... DRplay.pdf

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Greetings,

Bas - ON5HB

g1hbe
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Re: Best antenna no good signals?

Postby g1hbe » Tue Jun 04, 2019 12:10 pm

If you are receiving no signals at all, I suspect there is something more basic wrong. Two things spring to mind:

If you are using a pl259/sma adaptor, check that it's not a reverse type - there should be a central pin which mates with the hole in the SMA socket on the rsp1a.
Secondly, frequency entry is kHz by default on sdruno - if you enter 98.9 <enter>, you will be tuned to 98.9 kHz and you'll hear nothing. Use the MHz button to enter frequency in MHz format. It's the blue key on the mini keypad. The sdruno manual is not the clearest in the world, but a good read should get you going.
Your wire aerial should receive plenty of signals.

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Andy

k9zip
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Re: Best antenna no good signals?

Postby k9zip » Tue Jun 04, 2019 11:17 pm

Thanks I have a Mac and Mac using Cubic software.
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vk7jj
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Re: Best antenna no good signals?

Postby vk7jj » Wed Jun 05, 2019 9:12 am

Hi K9zip,

Cubic works fine on a number of different Macs I've tried it with although if you leave it running for long enough it invariably crashes with a memory leak but that's nothing to do with the issue. As Andy suggests it seems to be more than an antenna problem, I'm sure you've checked the RF gain setting from either the Settings menu or during Cubic's startup where it displays the settings dialog where you choose the RSP device.

That dialog's settings are editable, the default value being midrange 4 which is a good starting point because it means the RSP is not likely to be either deaf from overload or deaf from not enough RF gain.

Since you also invited comments about antennas you've given me an opportunity to get on my hobby-horse: if you have the room for a 33 foot long wire then you just may have room for a triangular shaped wire instead, ie. a horizontal delta loop, where the two ends come back to your feed point. You then use any form of twisted or parallel pair of wires as a feedline right down to your radio if possible. Since you have an RSP1A you will need a simple RF balun which I'm sure Gianfranco and others can help you with!

I can assure you that any random horizontal loop will serve you far better than any similar sized random end fed "long wire" because unlike a single wire it resonates on odd and even harmonics and it also helps enormously with noise as the parallel feed really does work well in reducing common mode noise.

--

I can't resist responding to the comment Bas made "There is no simple solution to receive all bands" with "yes there is, as long as you have the room".

Here is a simple horizontal delta built from cheap Aluminium welding wire with a simple twisted pair feed. The pattern is very close to omnidirectional, the Elev column is the angle of radiation and the dBi gain column is very pleasing.

My mission in life is to convince the world that end fed wires are absolutely horrible and that anyone who has one who can find a second remote mounting point to create any shape or size of horizontal delta should build one immediately ;-)

Phil VK7JJ

loop_bands.png
loop_bands.png (149.15 KiB) Viewed 1248 times

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k9zip
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Re: Best antenna no good signals?

Postby k9zip » Tue Jun 11, 2019 1:13 am

Thanks so much! Excellent information!

Mark S.

N2HAM
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Paul
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Re: Best antenna no good signals?

Postby Paul » Tue Jun 11, 2019 10:13 am

vk7jj wrote:Hi K9zip,
if you have the room for a 33 foot long wire then you just may have room for a triangular shaped wire instead, ie. a horizontal delta loop, where the two ends come back to your feed point. You then use any form of twisted or parallel pair of wires as a feedline right down to your radio if possible
.
Hi Phil
I find this really interesting. Can you comment please on whether the triangle type (e.g: equilateral etc) affects the performance accross the bands?
Best Wishes
Paul

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ON5HB
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Re: Best antenna no good signals?

Postby ON5HB » Sun Jun 16, 2019 4:06 pm

vk7jj wrote:My mission in life is to convince the world that end fed wires are absolutely horrible and that anyone who has one who can find a second remote mounting point to create any shape or size of horizontal delta should build one immediately ;-)


Same here. But they are not End-Fed, just sold as such.
As soon as you make it feeded at the end they stop working.

A true End-Fed has no counter, not even the coax to do it....but they never tell people.
In the end it's not and End-Fed but a longwire with a balun and a counter.

The End-Feds people are using use either the mast as counter as such not true-end-fed but off-center or bad dipole.
Or they use the coax as counter, again not being End-fed.

A dummyload with a long wire will perform better and can be considered a true-End-Fed, 1:1 and not much signal :lol:

They sell these fake things for 200 euro, when you can have a G5RV for just 40-50 euro, outperforming any multiband antenna out there, mostly on par with dipoles.

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Greetings,

Bas - ON5HB

vk7jj
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Re: Best antenna no good signals?

Postby vk7jj » Sat Jun 22, 2019 8:43 am

Hi Paul and hi Bas.

Apologies to you both as I didn't see the reply and question.

Paul, the triangle shape is very forgiving, building your triangle for the largest enclosed space is the best way to think about it but you would have to do horrible things to it to make much noticeable difference.

If you have a set of rough dimensions and heights I can sure model it for you and post the results to give us both some idea. The performance across the bands in terms of gain and angle of radiation is determined by the overall wire length, ie. the perimeter.

Many large loops are built by diligent hams as near to square as possible like traditional "quads", however modelling the ideal horizontal quad shape shows it has quite marked directivity while the triangle has as close to omni across all bands as one could realistically hope for.

Bas, yes, electrons cannot be pushed into the end of a conductor!

Most amateurs when you talk to them about end fed wires seem to appreciate that the wire is only part of a circuit whose other parts are the coax and the ground.

But they almost universally fail to appreciate that the exact same current that flows in their wire and thus radiates or receives, also flows and radiates and receives in their outside coax braid to the house, tower (if connected), coax braid in the shack, all the connected earth and neutral wires in their walls, the wire to their mains earth stake and then on to their neighbours.

All of that is the invisible half of their antenna and it is very very good at receiving noise because it is also directly connected to all the noise generating devices!

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Paul
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Re: Best antenna no good signals?

Postby Paul » Sat Jun 22, 2019 4:31 pm

Thank you Phil
Early days at the moment - considering where I might be looking at.
In a rural location, but space directionality somewhat restricted by various "obstacles."

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