Testing RSPduo receiver sensitivity with noise generator

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glovisol
Posts: 118
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Fri Jun 29, 2018 4:38 pm

Dear Phil, it is 18:00 hours and I am back (tired) from the Riviera. Tomorrow I shall study your material in detail. Here I wish to give you physical details of the Beverage and of my setup, because I fear it is far simpler than you imagined.

The antenna is held to the side of the house with a triple purchase tensioner and goes away into the distance to a wooden telephone type pole (no other poles in between). Average antenna height over ground is 6 m and horizontal length is 135 m, + 2 m lead-in, + 5.5 m to the junction box containing the terminating 560 Ohm resistor. Grounds at both ends with heavvy stakes as shown in the picture. Stake depth 1.7 m into humid clay grounds (extremely good for Barolo wine which I make). I have no feeding arrangements as the antenna loops thru the insulator and goes to the inside balun thru a small hole in a wooden window. More in the photos.

Kind regards,

Gianfranco
Attachments
Antenna receive side 2 .JPG
Antenna receive side 2 .JPG (150.57 KiB) Viewed 873 times
Antenna receive side 1.JPG
Antenna receive side 1.JPG (84.56 KiB) Viewed 873 times
Antenna going away.JPG
Antenna going away.JPG (176.02 KiB) Viewed 873 times

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glovisol
Posts: 118
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Fri Jun 29, 2018 4:39 pm

More photos....
Attachments
Inside works .JPG
Inside works .JPG (135.72 KiB) Viewed 873 times
Ground stake.JPG
Ground stake.JPG (138.31 KiB) Viewed 873 times

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vk7jj
Posts: 126
Joined: Thu Mar 02, 2017 9:56 am

Re: Testing RSPduo receiver sensitivity with noise generator

Postby vk7jj » Fri Jun 29, 2018 11:40 pm

Dear Gianfranco, I don't think I've corresponded with anyone from the Riviera before, especially someone bragging about coming home tired ;-)

Hope it all worked out well for you both and the problem was resolved! But, here we sit in the depth of winter and you're showing me sunny photos of vineyards and talking of home made wine and beverage antennas, a Freudian slip no doubt.

Lovely to see your situation, thank you for the unexpected bonus!

Here is your antenna as per your length and height figures minus the 5m feed in. It's modelled with your 560 ohm resistor, the SWR figures are calculated for a 450 ohm feed line. You might get to hear some rare DX on 6 and 2 if you avoid the ferrite bandwidth issue.

glovisol-beverage.png
glovisol-beverage.png (91.14 KiB) Viewed 858 times

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vk7jj
Posts: 126
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Re: Testing RSPduo receiver sensitivity with noise generator

Postby vk7jj » Fri Jun 29, 2018 11:54 pm

I should have done this properly before the above post. Suddenly occurred to me that I hadn't tried it below the 7MHz you originally spoke of using it for.

Here is your antenna from 1.8Mhz up. This time the SWR figures are calculated for a 300 ohm feed point. My wife wouldn't possibly let me drill a 450 ohm hole in her window, maybe a neat 300 slot is remotely possible though ;-)

That's one very interesting antenna isn't it.
glovisol-300.png
glovisol-300.png (107.11 KiB) Viewed 858 times

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glovisol
Posts: 118
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Sat Jun 30, 2018 7:46 am

Dear Phil,

I am simply amazed by (and a little envious of) your capabilities about antenna modeling. I have also seen you are also equipped with the AA - 1400, top of the range antenna analysis meter, so you are able to close the circle, from design, to modeling, to actual antenna measurement and I consider myself very lucky to have your help.

You have now compelled my attention and interest to the extreme bandwith of the Beverage antenna, while previously my involvement with the RSPduo was with VLF to HF only. By going from an unterminated 30 m wire and no baluns to a 135 m terminated Beverage and painstakingly tested wireline, ferrite loaded baluns, I went from almost no signal received, to crowded HF bands in just 15 days.

I agree with you that baluns, while dramatically improving Beverage performance, steal one of the best features, e.g. extremely wide bandwith. On the other hand, unless you reside on a mountain top, the biggest drawback in using a long Beverage above 28 MHz is antenna elevation. In 1950 to 1960 I worked on 14.300 SSB, but was very much involved with VHF, UHF and SHF as well. For 144 and 432 MHz it was Yagis as high as I could place them, for 1296 MHz it was a converted APX6 (you certainly remember lighthouse tubes) and parabolas. I even wrote an article on APX 6 conversion on 73 Magazine, 1960.

Based on your work, my idea is to proceed as follows:

1) Complete the development work on the trifilar / quadrifilar balun in order to cover the 1 - 30 MHz frequency range with the existing 135 m Beverage. In this respect I look forward to your comments on pro and cons of using twisted wireline vs. "normal" primary - secondary windings. I am also prepared to use two baluns here, with band switching, because of limited bandwith.

2) Based on your suggestions, build a "short" Beverage which I plan to install as high as possible over the roof of the house with a balanced lead-in to cover the range 70 to 470 MHz. As far as I know, using a wire antenna in place of directional rotating Yagis or Logs, should be a very interesting project. Perhaps you could model one for me... If this works, then it should be possible to use 3 / 4 Beverages and cover all directions i.e. a "static / rotable antenna!

I have managed to test the new quadrifilar wireline 10 turns balun, which is the best in practice on the RSPduo up to 7 MHz. It has zero insertion loss, but (as you would know already) a limited frequency response. Today I shall reduce the number of turns.

Kind regards,

Gianfranco
Attachments
Quadra Balun 10t.jpg
Quadra Balun 10t.jpg (68.92 KiB) Viewed 834 times

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glovisol
Posts: 118
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Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Sat Jun 30, 2018 7:58 am

Dear Phil,

On second thought wonder if you could look again at your last antenna model and provide R / JX data from 2 to 14 MHz, but evenly spaced, i.e. every MHz. It should then be possible to implement an autotuner which could zero the capacitive term at every frequency....

What worries me is the apparent discontinuity between 10.12 and 18.12 MHz.

Cheers,

Gianfranco
Attachments
ANTENNA REACTANCE tune.jpg
ANTENNA REACTANCE tune.jpg (27.91 KiB) Viewed 678 times

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vk7jj
Posts: 126
Joined: Thu Mar 02, 2017 9:56 am

Re: Testing RSPduo receiver sensitivity with noise generator

Postby vk7jj » Sat Jun 30, 2018 8:24 am

Hello again Gianfranco,

I'm not like the soothsayer in Antony & Cleopatra "In nature's infinite book of secrecy, a little I can read", the reality is I'm like the blind theologian looking in a dark room for a black cat which is not there. The problem is my conceit and impatience sometimes makes me think I've found it, so beware!

Happy to do the 2-14MHz modelling, will post it a bit later, all going well.

Before pushing forward though there is another consideration. The models are based on the view in the pic below - a classic Beverage - which as you can see has the feed point at the bottom of your blue wire, between it and your earth stake, at the red dot. Hence my comment about bringing a ladder feeder in through your window.

I wonder if you are willing to reconfigure things temporarily that way for a test? It looks like the blue wire connected to the top of your Beverage at your window might be able to drop down to the earth stake instead of coming in the window so that you could on one of your very many sunny days place the RSP and your balun at the earth stake and extend the USB cable up through your temporarily open window?

Otherwise, if that is not convenient, I should try to remodel it based on the reality of your situation.

Sincerely, Phil

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vk7jj
Posts: 126
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Re: Testing RSPduo receiver sensitivity with noise generator

Postby vk7jj » Sat Jun 30, 2018 8:36 am

Here is the 2-14MHz table
g-b-2-14.png
g-b-2-14.png (121.23 KiB) Viewed 819 times

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glovisol
Posts: 118
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Sat Jun 30, 2018 8:49 am

Dear Phil,

You are not Shakespeare's soothsayer, but rather Dante's Virgil leading me into the mysterious land of Beverage (will drink a Nebbiolo bottle to your health for lunch).

Splendid idea, I am going to move the connections today and thanks for the new data. Have a splendid wekend!

Gianfranco

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glovisol
Posts: 118
Joined: Thu May 10, 2018 6:42 pm
Location: Piedmont, Italy

Re: Testing RSPduo receiver sensitivity with noise generator

Postby glovisol » Sun Jul 01, 2018 6:22 am

Dear Phil,

The RSPduo relocation is completed and I am now ready to test the system as you proposed. With reference to the pictures, I have lenghtened the antenna lead (blue wire from top) by 2.5 m and it goes directly to the RSP. The ground lead between stake and RSP is less than 1 m. As soon as I switched on I could immediately see a lot of amateur stations on 14 & 7 Mhz, which normally disappear at this time of the day (8:20 and sun high up). Will post results tomorrow morning.

Kind regards,

Gianfranco
Attachments
DSC_1110 (Medium).JPG
DSC_1110 (Medium).JPG (129.78 KiB) Viewed 746 times
DSC_1109 (Medium).JPG
DSC_1109 (Medium).JPG (68.31 KiB) Viewed 746 times
DSC_1108 (Medium).JPG
DSC_1108 (Medium).JPG (131.44 KiB) Viewed 746 times

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