Tag Archives: s9v31

Lowering the HF Noise Floor

Previous posts have reported on WSPR performance with my vertical antennas especially compared to data collected by a nearby Ham (Cliff – N5CEY) with a similar antenna setup. The metric is how well a given antenna receives unique spots over a 24 hour period as documented by the WSPR Challenge site. I have always seemed to lag behind Cliff’s receive performance in spots and in DX received. I have asked Cliff about the specifics of his setup and came to the conclusion that he has a significantly lower noise floor at his QTH in the country versus mine in the city. Cliff’s QTH is about 12.5 miles north of mine in a rural area. He is closer to the coast and likely has much better soil conditions as well. His antennas on WSPR are all 1/4 wave verticals on 40m, 30m and 20m. I have an “ugly” balun installed at the feed point of my vertical and about 30 feet of RG-8X to the shack entrance. There are about 8 loops of coax at the shack entrance. Inside the shack are various patch cables connecting switches, antenna tuners, SWR meters and the Timewave ANC-4 to the IC-7300. Lots of nearby noise sources including PC’s, cable modems, wifi routers etc.

So the task before me is how to lower the noise floor at my QTH to bring in weaker signals. I have done quite a bit of research and finally came upon some discussion of the effects of Common Mode currents on noise floor. My next post will detail some measurements on various common mode current chokes but for now suffice it to say that changing my common mode choke arrangement has had a positive effect on the noise floor. Here is what I did:

  1. Added a CMC consisting of 12 turns of RG-8X around a FT240-43 toroid core right at the IC-7300 antenna connection. This resulted in a 1 S (6dB) unit reduction in the received noise!
  2. Replaced the ugly balun with a choke as above. No significant change noted in noise floor.
  3. Replaced 30 feet of RG-8x feed line to the shack with 30 ft of RG-213 coax. No significant change in the noise floor was noted. this change should help in reducing losses though.

Adding the choke to the antenna input made a big improvement in lowering the noise floor. I adjusted the Timewave ANC-4 to further try and negate any remaining noise.

So the results are as follows after 20m WSPR was run for 24 hours:

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Pulled ahead of N5CEY by 8 unique spots and made the DX list still lagging a bit behind Cliff. Here are my spots during this period (right image is Cliff’s and the one on the left is mine):

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So all in all a significant improvement by addressing Common Mode Currents. More on the Chokes in an up comming post.

 

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The S9V31 is Working…but How Well?

I have been trying to collect some solid data on the performance of the S9V31 antenna configured for multi-band operation. It is currently configured to be non-resonant on any band and I go through an antenna tuner in the shack. WSPR results have been lackluster and possibly a little worse than when run as a resonant 40m antenna. FT-8 spots on pskreporter.com on the other had have been quite good on early morning 40m. I am being heard all along the western Pacific rim consistently.

I have noticed quite a few stronger European stations in the late afternoon on 20m and have made several SSB contacts. I actually closed four all time new ones this week: St Eustatius on 12m, Republic of Congo & Easter Island on 17m, and Revillagigedo Island on 20m. Interesting that 12m and 10m have had brief openings in the late afternoon. Band conditions have been pretty bad with long periods of zero sunspot numbers.

I am still working on what to do to lower the noise floor at the shack. I feel that is the key to improve station performance and should be readily visible when running WSPR. More on that coming up….

 

The Alpha Antenna S9v31 is On the Air

After a full year of experimentation with vertical antennas I finally deployed the Alpha Antennas S9v31 antenna. It was a perfect day here for it as well. Mid 80’s with very little wind. A bit muggy for the work on the radial field but otherwise just a beautiful day in South Texas!

First up was finishing up the radial field. I set out the radial plate with 20 radials with lengths that vary from about 10 feet to just over 25 feet. The back breaking job was installing the lawn staples to hold them down. Tedious but straightforward. The yard was freshly mowed and I had tested three long radials and found no issues with the mower. Here is the finished radials:

Next I removed the 20m vertical element and finally lowered the SOTAbeams travel mast. This mast took a great deal of abuse over the past year or so and all told is still in serviceable shape. I highly recommend this mast!

The setup of the S9 was really simple. The mast is extended on the ground and a set of clips installed at each section joint to prevent collapse. The radiating wire is inside the mast. Once extended it is walked up and I mounted it onto the same aluminum angle I used with the travel mast. The hook ups remained the same with the junction box and ugly balance used before.

Here is the finished product:

I am running WSPR on this now so will report on performance after I collect some additional data.

Annual Yard Clean Up is Finished…Well Almost

Took some time over the last few days to get the yard cleaned up and trees pruned. Although the National Weather Service shows our precipitation year to date tracking as normal for the area, it just seems dry. April May and June are wet months for us so hopefully it will pick up. The impact all thi shas on my ham radio activities is that I had to pull up my test vertical antenna and the ground radials in order to cut the grass. Now that all this is done I can look at installing the radials permanently. All of this is in advance of testing some more verticals before I install the S9V31 antenna permanently. Currently I am planning to try the vertical as a resonant 40m/15m antenna with radials, the end fed antenna with the 9:1 matchbox connected to the ground radial field and finally the s9v31 with a remote tuner and the radial field. Overall I am getting close to completing my tests and getting my final configuration on the air.

17m Is Alive and Well

Noticed that 17m has been open in the morning and early afternoon into Europe and Central & South America. I made some SSB contacts as well as a bunch of JT-65. So now I am operating a bit more as I recover from the surgery. Can’t really work on my antennas yet although I do have plans for installing the S9V31 soon. I will be laying out at least 16 radials and will use the LDG RT-100 remote tuner I just acquired used at the base of the antenna. Hopefully the doc will clear me to do some light work next week about the time the tuner arrives.

Planning My New Base Antenna

I am making plans to setup my S9V31 antenna as my new base antenna. I have tested a similar arrangement with a 4:1 balun and 12, 16ft radials with no issues. I have found a used RT-100 remote tuner which I will use at the base of the antenna.When it arrives and I get some strength back I’ll set it up in the yard about 30 feet from the house.

Testing proceeds on the 30 foot Vertical

I setup the travel mast as before with 30 ft of #16 wire strung up vertically. This time I connected it to a 4:1 balun and added 12, 16 ft radials layed out on the grass. Where there is little space I just wrapped and folded the radials to fit the available space. It is located about 20 feet from the house. This is a temporary rig to evaluate its performance versus the end feed version. Right now I am running 1W WSPR on the 20m band. Here is the 24 hour performance:

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This worked out to 108 unique spots…not enough to make the challenge board but still respectable. Will complete these next 24 houyrs at 00:00 UTC and then switch to 40m for two days. I’ll then do the same with the end fed match box.