Tag Archives: noise

The RA0SMS Mini-Whip Antenna

I just received a mini-whip antenna from RA0SMS in Russia.The mini-whip is an active receive antenna that is particularly useful in the low bands. I plan to set this up outside and up as far as I can get it. I’ll use 75Ohm cable TV feed line to bring it in the shack and connect it directly to the SDR play receiver. I have been sharing the discone with my VHF rig and the SDR play so I switch between them when I need the SDR as a panadapter. I am hoping this antenna will work well so I can dedicate it to the panadapter function on HF. The antenna consists of the external antenna and circuitry in a PVC case and a small bias-t box to send 12V up the cable to power it.Here is what it looks like after I unboxed it:




As I have stated before, I am a causal contester. The ARRL DX SSB contest was running this weekend and I used it as an opportunity to test the vertical 31 foot antenna as an end fed with a 9:1 balun with the IC-7100 radio and tuner. I figured this would be good to test on 20m during the day and 40m at night. I didn’t join in until Saturday afternoon and found that nearly all the action was on 15m which tuned up well on the antenna. There was also activity on 10m and 20m. All told I made around 30 contacts using “search and pounce” all of which were DX stations. Sunday morning I tried 40m and made a JA contact, my first on 40m! I was hearing Indonesia as well.

All in all good results of my antenna and rig. This shows that a multiband antenna is very useful to adjust to changing band conditions and that the increased receive sensitivity is being put to good use.

As always, I am shocked to hear so much activity on contest days on bands that one usually thinks are dead. I may start making a point to call CQ on these bands and see if anyone is listening. I may be surprised!

Busy Week on 20m WSPR

I have been running experiments on various antennas this week on 20m WSPR. NO5V is my current base antenna, the Ultimax DXtreme 53 footer up about 20 feet and horizontal. NO5V/1 is the EFHW tuned for 20m and NO5V/2 is the same wire as the EFHW but run as a non-resonant end fed with a 9:1 matchbox and about 30 feet of coax as counterpoise. I am also able to compare this data with that from N5CEY who is running a 1/4 wave vertical at his QTH about 20 miles from here. I will be looking at formally crunching the data but what is apparent is that the current base antenna is not as sensitive on receive as the vertical antennas. This is based on the WSPR Challenge results and A vs. B listening tests. The verticals are nearly equal in receive capability with the EFHW marginally the best. Both of my verticals compare well with N5CEY’s 1/4 wave vertical but he still seems to have a slightly more sensitive system as he gets better signal reports on WSPR from more DX stations.I plan to setup my own 1/4 wave vertical this week to evaluate before I turn my attention to the S9V31.

I did a quick test on 40m in the NO5V/2 configuration and was getting good 40m results as well.

Noise Raises its Ugly Head

I am seeing some weird noise on mainly the low bands here with the new vertical antenna. It is fairly broadband and the rig’s noise blanker seems to effectively null it but I would like to track down the source.The weird part is that is seems to go away on it’s own during daylight hours and return in the evening. I haven’t been able to track a specific time yet. I suspect somethjing here in the shack is causing the problem. I walked around the property yesterday with a battery powered receiver and I see the noise coming from the wall around my workstation. I suspect a bad patch cable as this has caused problems before and I did add some patch cables that may be a bit dodgy.