Tag Archives: WSPR

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:


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):

2018-03-18 (1)2018-03-18

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



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.

Inadvertently Stress Testing a Homebrew Buddistick

I took out my homebrew Buddistick over the weekend to test its performance versus the full size verticals I have been playing with. I haven’t really deployed this in some time so I was able to make some comparisons to some of the antennas I have been working with lately, namely the 1/4 wave ground mounted verticals. Setup up was about as easy as I remembered it but certainly more complicated than the ground mounted vertical. It is also heavier than I remembered it to be. I had it setup with three guy lines and a single elevated radial and it tuned to 1.46 SWR on the 20m band. On 20m it is not a full size radiator and relies on a small coil to bring it to resonance.

Performance was actually quite good on 20m WSPR. Two days in a row I made the WSPR challenge board. It still remains about 20 spots below the nearby station of N5CEY. The number of spots on 1/2W transmit was about equal to the number of receive spots which I am finding to be a good indicator of antenna efficiency. Thais tells me what I already knew, that is, it is a good QRP field antenna.

The antenna went up Saturday afternoon and stayed up through Monday afternoon. Monday it got breezy here at the QTH. Wind speeds picked up to around 20mph with gusts to 35mph. At some point, the camera tripod failed at the point where the PVC pipe meets the tripod. The whole mess came down hard. Fortunately, the whip was spared any damage and the tripod can be repaired.


For my next trick I am going to try and replace the whip with a fishing pole and wire with an elevated radial. Should be much lighter. It has also proven to be much more resistant to the “valley Wind Machine” that builds up around here this time of year.

40-20-15m EFHW Round 2 – Update

WSPR results o 40m and 20m WSPR look good with the EFHW. here is 40m during nightime hours:


And 20m for just a few hours yesterday and so far this morning:


On 40m there have been 103 unique heard vs 106 heard by (@1/2 W). On 20m, this is 124 unique heard vs. 74 heard by (also @1/2 W). These numbers indicate good overall performance.

I found a great write up on how to build one of these antennas titled “A Shortened Multi-band End-Fed half Wave (EFHW) Antenna for 80-10m” by Steve Nichols, G0KYA.

I am going to do some work on how to best deploy this in the field given my typical situation (i.e. lack of tall trees). this could be a great Field Day antenna.

40-20-15 EFHW

Here are the 24 hour WSPR results on 40-20-15m receive using band hopping. They appear to be pretty consistent with current band conditions and while not as good as the 1/4 wave vertical it is a very respectable and very portable multi-band antenna.




The SWR plot is as follows:


These antennas are increasingly popular and many quality antennas sell for ~$140. Building your own is very simple and I would estimate my cost to build this would not be greater than $30. This will work out to be a good antenna for portable or field day use. It is not especially sensitive to mounting or orientation.


More Test Results of The Ground Beam QEC Antenna

Tried 20m FT-8 early this morning as VOACAP indicated this was the best time for EU contacts on this band. My signals were heard toward the Northeast US but very few were heard in the EU. I made no QSO’s. WSPR results over 24 hours are here:

wspr mapo

This data appears to confirm that this antenna is directional (I have it pointed at a 45° bearing from my QTH)  but the F/B ratio is still relatively poor. The antenna is about the same as the 1/4 wave vertical overall. I must say that my single reports in the forward direction on SSB have been very good. Propagation on 20m is not helping. VOACAP shows the following based on 100W SSB with the receiving antenna based on a dipole at 10m:


20m has been largely dead after dark. This chart indicates that 20m contacts with this combination of antennas and power will be challenging to the EU.

Overall, The ground beam – QEC antenna is an easy to carry and deploy vertical antenna with just enough directionality to help in some situation. It is well suited to my QTH on filed day as it has a wide enough bandwidth to cover the USA and Canada.

Initial impressions of the Timewave ANC-4 Antenna Noise Canceller

My used Timewave ANC-4 arrived yesterday from Ebay. It lacked a power connector which fortunately I had in my junk box. I wired the cable up and added some power poles. It came with an antenna that consists of about 8 feet of wire connected to the center pin of an RCA plug. I set this up roughly vertically inside the shack. The unit must be grounded to work effectively with this wire antenna. I fiddled with it awhile but did not have much luck in reducing noise initially. Per the manual, the first thing to try was ensure that the sense antenna was picking up the noise at about the same amplitude as the main antenna. The receiver is setup to an unused frequency and the noise level measured on the S-meter. The phase and noise gain controls are fully CCW. The  main antenna was disconnected and the noise gain adjusted until it matches the S-meter reading  measured previously. The main antenna is then reconnected and the phase control is adjusted until a null is found.

This took awhile to figure out but with the IC-7300 it is easy to see the results on the waterfall. As you get close to a null the background on the waterfall will darken and signals will become more distinct. I estimate that the change is about a 2 S unit reduction in noise. I have run the unit on 20m WSPR and over a 1 hour period had 42 unique spots compared to N5CEY’s 21 unique spots.

So initial results look promising. I will need to work more with this and collect some data on to its effectiveness.

Insight from running 20m WSPR

The 40m vertical has been deployed for the past few months supported by a 10m SOTAbeams travel mast. It has held up well to the abuse of constant use over the summer. We had a few windy days last week and some of the seconds of telescoping pole retracted so I had to bring the whole thing down to fix. During this time I ran the 20m vertical on its own using 20m WSPR for receive only. Over this two day period I was comparing with Cliff’s (N5CEY) 20m WSPR station about 15-20 miles away near Bayview. Cliff consistently gets a larger number of unique spots as well as a larger amount of DX calls with his setup. Cliff is in a rural setting while I am in the middle of the city. What the WSPR data is telling me is that my noise floor is higher so I am not receiving as well as Cliff does out in the country. I took some measurements with the IC-7300 at various times of day and found the following noise floors:

Band Time
1800 UTC 2100 UTC 1300 UTC
80m S3 S4-S5 S6
40m S6 S6-S7 S9+5
20m S1 S2 S4-S5
17m S3 S3-S4 S5
15m S3 S1 S7
12m S2 S0 S3
10m S1-S3 S1 S5

These measurements were made with no preamp on 20m and below. All others had preamp #1 engaged. Friday night was awful, S9+ noise on 40m! Dick, WB5B said it best: “WSPR is telling you that you have a noise problem!” Doh!

630m WSPR

Cliff, N5CEY, has been listening to 630m WSPR stations over the past few days and has been consistently picking up three or four stations a night with his antenna system. I thought I would try the same using just the mini-whip antenna and the SDRplay receiver. The mini-whip has been fairly decent on the lower bands. I cranked up HDSDR and when I tuned to the WSPR frequency of 474.2 kHz and found a huge amount of inter-modulation products from local broadcast stations. I tried lowering the gain but they didn’t go away. Looks like I will need a low pass filter or an attenuator.

I then switched to using the SDRuno software that goes along with the SDRplay. It has some filtering features that I thought would be useful to try. The waterfall looked a lot quieter with this software for some reason and after piping the output to WSJT-X I was able to decode 630m WSPR spots from three stations overnight. This compares favorable to what N5CEY saw over the same period.

I will be playing with this some more to see if I can further optimize the receive.