Category Archives: ham radio

Don’t Drop the Toroid!

I sat down to start working on the phase transformer for my phased vertical project. I dropped the toroid!

Sigh!

Just ordered a replacement. Hope it arrives before I break for Christmas….

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Using SDR Receivers to Track NOAA Weather Balloons

Found an article by the folks at RTL-SDR that shows how to recieve data from NOAA weather balloons. This look like a fun project and considering the balloons at the NWS Brownsville are launched twice a day just 2 miles from here it could be very doable.

Tips for FT8 DXers

Tips for FT-8 DXers by Gary Hinson, ZL2IFB is online at the WSJT website. Nice tips on using FT-8. Check it out.

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:

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

2017-12-11_9-55-11

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 Round 2

There were some things bothering me about the EFHW matchbox. I would run a scan using the RigExpert with a 3.9K Ohm resistor from the antenna line across to the ground and sometimes get a good reading and sometimes not. I suspected a poor solder connection or the el cheapo binding posts I was using. Well I am done with the el cheapo binding posts! From now on I am using stainless steel machine screw hardware. I replaced the binding posts with these and the readings settled out.

I made a few other changes for round 2 with this antenna today. First up, I wrapped the end of the RG-58 cable eights times around an FT240-43 core to act as a choke at the feedpoint. I added about six feet of counterpoise. I went back to setting this up a a low inverted V of sorts. The feedpoint is over a tree branch on one end about 6 feet off the ground. The other end is supported by a fishing pole. Unfortunately, this configuration had a huge amount of sag in the middle. I placed another pole in the middle so the apex is up about 16 feet. Not happy with this configuration. I will use a sturdier pole and set this up as a true inverted v next time around. meanwhile, I am running some test in this configuration. SWR was good on 40m and 20m but a bit high on 15m:

efhw

Initial WSPR results on 20m look promising. 1/2W signal is showing a good ratio to received spots. I tried a few SSB contacts but none were closed. I’ll run WSPR on this over night on 40m and 20m and see what the data shows. I’ll then switch to a 10m pole to support the middle of the wire into an inverted V.

One more thought is that I’ll add a 110uH coil to the end of the wire then about 2m more of wire, the idea that it can trap 40m and then act as a loading coil on 80m. I have worked out the coil dims for this using a 1-1/4″ PVC pipe coupler as a coil form. 110uH works out to 52 turns of #20 magnet wire.

VHF Packet Winlink Working

Back in July,  I did some work to get packet winlink working over the local HF packet nodes. At the time, the local digipeter was not operating so I was not able to make a solid enough connection to exchange mail. The digipeter node is now operational here in Brownsville. I gave it a try after reviewing how I had done it before using the IC-7100 and a software soundcard modem. Quick review:

  1. CAT7200 software is installed and then run to create a com port that the IC-7100 will recognize for CAT control.
  2. UZ7HO Sound Modem software performs the TNC function via soundcard mode.
  3. RMS Express is run in packet winlink mode to exchange mail.

The radio is set manually to the digipeter frequency which in my case is 145.01 Mhz. An ultra important step is to set the mode to FM-D. Once all this was set I was successful in sending and receiving email at 1200 baud. Not bad for a soundcard mode.

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.

40m40m

20m20m

15m15m

The SWR plot is as follows:

swr

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.

 

EFHW Broadband Transformer On the Air

Back in late August, I had a post regarding a broadband auto transformer for an EFHW antenna. I finally got around to cutting 66ft of wire (1/2 wave on 40m) and did some basic tests. It is only up about 10 ft and stretched out north-south across the back yard. The RigExpert Zoom showed dips in the 40m, 20m & 15m bands. SWR is below 2:1 across each band. Twenty-five feet of coax forms the counterpoise. Very promising. One SSB contact on 20m yielded a 57 report on this antenna and the 1/4 wave vertical. I am running WSPR now on 40m. Tomorrow I will raise this up to a least 20ft and run some more tests. If I add another 66ft it will be a 1/2 wave on 80m and should get me a match on all bands (except 60m) between 80m and 10m.

Junction Box for Vertical Antenna

Here is a simple junction box I built to simplify setting up a vertical antenna. The hardware is all stainless steel. There is a 1Meg resistor across the feed-point to bleed off any static. This box will replace a coax pigtail. Ground radials connect to one lug and the vertical element to the other. The coax from the ugly balun connects directly to the UHF connector.

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Antenna Cleanup

I took down the ground beam QEC antenna and the 20m quarter wave element that I had connected to my 40m vertical today. I am not really seeing much of a difference on 20m although I need to use the tuner now.

I have some construction projects I need to finish before I make some additional antenna tests. I am building some boxes to clean up vertical antenna setups. I am also working on the phase transformer box for the 20m phased vertical experiments. There are feed lines to prepare for this.

Once I have the vertical feed boxes complete I would like to convert the vertical to an end fed with ground radials. I recall this configuration worked pretty well.