Tag Archives: ham radio

A 20m Vertical Dipole…(I am a glutton for punishment)…

Here in South Texas you hear a lot about the Canicula. July 14 through August 24th is considered to be the hottest part of the year. It’s 94° F here today but when you add the 54% humidity we get a heat index of 106° F. So naturally I choose today to play with a new antenna!

I built a vertical dipole for 20m today using two Workman Hamsticks. I thought this would be fairly easy as I didn’t have to get it too far off the ground. More on that later…

I read that one ham had pretty good luck with the stinger set at 38″ so I set that as a starting point. I set it up vertically on a painters pole with the bottom stinger about a foot off the ground and found the SWR minimum was in the 13.5 Mhz range. I shortend the stingers and the SWR went down to the 13 Mhz range. I played with this for some time until the whole mess collapsed in the breeze. Arrrgh!

I came inside and after re-hydrating played around with the antenna again. Nothing I did seemsed to work in getting it to tune in the 14m band. I got it back to the original configuration and ventured outside again. I set it up as before and the SWR was in the 13.5Mhz range again. This time I guyed the painters pole and sent it up a few feet. The SWR started going down with the minimum frequency going up into the 20m band…Aha! I raised it up so the feed point was about 15 to 16 ft off the ground. This put the end of the stinger at about 8 feet.  Now the SWR response looked good with 2:1 or less across most of the 20m band.

Inside again now I started to tune around and found the SWR swinging again. Suspected Common Mode Currents again so went outside and lowered the antenna to 8 feet, redressed the coax so that it comes out away from the feed point at 90° for about three feet. Now everything is working out fine. I made an SSB contact to Chile and to Guatemala right off.

So here is what I learned today:

  1. It is too hot in South Texas in August to play with antennas…wait till early morning or very late in the afternoon next time.
  2. A vertical dipole needs to be a few feet off the ground to tune properly
  3. It is vitally important that the coax feed line in a vertical dipole come out at at 90° angle for several feet to avoid common mode currents.

Here is a view of the antenna:

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Here is the SWR plot:

20m dipole vert

Will run 1W WSPR for 24 hours and compare data with the 1/4 Wave vertical.

 

 

My Ugly Balun

I built an ugly balun today to try and address the SWR swings I was getting on 20m. It actually went together in about 10 minutes. To build it I used a 4″ PVC pipe coupler as a form. I drilled two small holes to run a tie wrap through to hold the end of the coax in place. I had a 25 foot piece of RG-8X laying around with PL-259 connectors on each end. I wrapped 15 turns around the coupler and then tied it off the same was as the other end. Some long tie wraps then are used to hold the winding securely on the form. I replaced the 1:1 current balun I had been using with this. To match up the coax connectors I used two bulkhead connectors and wrapped with electrical tape (for now). Here’s what the finished balun looks like:

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And here it is installed at the vertical antenna feedpoint:

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The balun seems to help with the SWR issues on 20m but I see some shifts in the overall SWR response. I’ll likely have to tweak that over the next few days.I have some ferrite toroids on the way as well and will try and build a choke with those as well. Signal reports on both 40m and 20m SSB were real good tonight!

 

What’s Better than One 1/4 Wave Vertical? —How About Two?…

Next experiment in vertical HF antennas is trying a 1/4 wave vertical “fan dipole”. The 7.2m fishing rods are a perfect support for up to a 20m wire radiator. I set a length of 3/4″ PVC pipe about a foot away from the existing 40m 1/4 antenna. I also removed the last two section of fishing pole as they are too flimsy and are not needed length to support a 20m wire. I connected this wire to the point where the 40m wire connects and after a bit of tuning had three dips in the SWR. 7 MHz is the main tuned frequency, 14 MHz is the new radiator and 21 MHz is the third harmonic of the main radiator. Here is the SWR plot:

swr

Here is what is looks like:

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So far this works well as before on 40m and 15m. The performance on 20m looks a little shaky still as I am seeing my SWR swing around a bit when transmitting. This indicates to me that my feed line is picking up RF at that frequency. I’ll be building an Ugly Balun soon to try and clean that up. The antenna hears very well on 20m with very little noise so I f I can solve the SWR issue I should be in good shape.

 

First Beachside Setup

Got started a bit late last night but managed to set up the beachside balcony station. I wrapped 30 feet of wire around the fishing pole and attached the end fed matchbox. I strung the coax around the balancing floor. The “mast” is self supporting in a nearly vertical orientation. I set up the FT-817ND with the tuner and amplifier set for 45w out.

The 20m band tuned right up but the band was quite dead by the late night evening. I moved to 40m and found a bit more activity but no contacts were made. The noise floor was surprisingly low on 40m considering there was lightning visible offshore. No contacts were made although I did pick up Roberto I2VRN with a solid 59. Could not bust the pileup.

All this being said will try this setup again this afternoon and try and scare up a QSO.

To the Beach!

Taking the FT-817 to South Padre Island today. I don’t have the artificial ground yet but will try without it. I can try two antennas. The first is the end fed antenna with a 9:1 matchbox. Will try and wind 30 ft of wire on the 26 foot pole. I’ll have to run with a tuner and spread out the coax on the floor of the balcony. May also run a wire down about 20 feet as a counterpoise. Next choice is a vertical 20m dipole. For that I’ll run a 16 ft wire vertical and another hanging from the balcony and use a 1:1 current balun. I am on the third floor of a wood and brick structure and an about 150 yards from the Gulf of Mexico.

Homebrew Artificial Ground

I will be operating on a third floor condo by the beach at South Padre Island, Texas soon and am thinking through the antenna. I have clear space above the balcony so a temporary vertical is certainly feasible using the new 7.2m crappie poles I just got in from Ebay. The problem is that I can’t really set up a decent ground system. An end fed vertical comes to mind but would need at least 30 ft of coax snaking around the balcony. Ground radials are out as are elevated radials. A vertical dipole would be feasible either with wire or perhaps a pair of ham sticks. Issue may be keeping the lower half coming in contact with folks in the lower balconies.

I’ll likely work out a vertical dipole but I am thinking of using an artificial ground with an end fed vertical. I have some plans for such a unit and may convert a unused manual MFG tuner to that purpose. Will scope out the site today and see what is feasible.

Update: 7/24/2017 Found a used MFJ artificial ground unit on eBay and won a low ball bid. Will try that with the end fed antenna and some counterpoise wire. 

First DX Using FT8

Made my first two DX contacts to Australia today on 40m FT8. I need to get used to the faster pace but otherwise looks like it works pretty well. I added the FT8 mode to HRD logging software and am uploading the contacts as “DATA” to LoTW.

Exploring a New Digitial Mode: FT8

Joe Taylor is testing a new digital mode called FT8. The development version of WSJT-X software now supports this mode. FT8 ( Franke-Taylor design, 8-FSK modulation) works similar to the more familiar JT-65 and JT-9 modes except the T/R cycle completes in just 15 seconds thus greatly reducing the time to complete a QSO. The bandwidth of the signal is 47 Hz and the decoding threshold is -20dB.

ft8

I downloaded the development version this morning and tried FT8 on 40m. There were just a few signals but I did close my first QSO. Pskreporter showed my signals was also being received in Australia this morning. Some things to note: Logging may not work and I understand that LoTW does not recognize FT8 as of yet. Also, the software autoexecutes the T/R sequence once the QSO starts. You have less than 2 seconds to select the station to respond too!

 

VHF Winlink

I started looking into how to use VHF Winlink with the Icom 7100 and it’s built in sound card. I am close to getting this working. The Mail server nodes are all in the Harlingen Tx area about 30-40 miles from my QTH. The closest working digipeter is in La Feria, TX. Sadly, there does not appear to be a working digipeter in Brownsville. In order to get everything working you will need the following:

  1. CAT7200 software – This creates a virtual serial port that maps to the IC-7100 USB CV-I interface. Pretty handy software and should work for other older programs as well. Good overview of the setup can be found on WB4SON’s blog.
  2. UZ7HO SoundModem – This is a software TNC that connects to the virtual port created above and to the RMS Express software via TCP connection. W2YG has some good material on setup for Signalink hardware.
  3. RMS Express – I have used this before for HF email using WINMOR. For VHF at 1200 baud you will need to use packet winlink.

For setup info recommend seeing the video by K4REF showing an overview of the usage. I cannot report 100% success at this time. I am able to connect to the mail server and start handshaking with it. Unfortunately, no mail has been exchanged. I suspect that packets are being lost in the exchange resulting in retries and eventually it gives up. I’ll be playing with this some more and see if I can get a message through. Hard part is done with the rig and software setups.

Post Field Day Report

I got a late start to field day this year due to a late breaking family commitment. Our club tried to setup at the local weather station but cancelled operations due to a large noise source crashing the bands at that location.

I started operating about 19:30 UTC. I started at 5W on SSB but over the first hour only made one contact. The band conditions were not good on 20m with lots of QRM and QSB. I added the amplifier and started to work on 45W. My power draw was significantly higher but my Q rate increased. The solar panel kept up with the power consumption even though there was quite a bit of cloudiness. I continued to operate on 20m until dusk when I switched to 40m. Overall I made 60 Phone contacts over the course of about 8 hours. My score this year will be lower even with more Q’s due to the higher power I ran. I did not get a chance to run digital.

What worked:

  1. Digital logging – netbook needed one charge cycle during this period. The 12V to 18V DC-DC converter was running at abou 2.2A during the charging cycle. I used a 7Ahr for this through a spare Solar Charge controller. I am going to look at a tablet for next year.
  2. The EFHW antenna worked great on 20m.
  3. SOTAbeams travel mast + TV tripod worked great to support antenna with no guy lines.
  4. Solar generator box had enough juice to supply the day’s activity even at the higher power consumption and had some power to spare.
  5. Tube Tarp came in real handy as shade. Luckily no rain on Saturday. I’ll do better with the depolyment next time as I figured out how to guy it better.

What did not work so good:

  1. Can’t run digital mode while using an amp. The amp uses the ACC port on the radio but provides no pass through. I am looking at how I can accomplish this for next time.
  2. I don’t have the battery budget to run 45W phone for 24 hours. I figure I would have run out of power after about 12 hours. Partly cloudy day didn’t help.
  3. Didn’t take advantage of more 6 stations to raise Q count.
  4. Calling CQ consumes a lot of power. Need to refactor the power budget.

So I figure my score this year for 60 SSB QSO’s + bonus points for emergency power will work out to 310 for my 1B station. I am convinced now that I have to finish learning CW so that next year I can run 5W on CW and up my point count. A more directional antenna would be nice but a portable beam antenna remains elusive. For some reason I seemed to be doing better with stations in California than on the more densely populated east coast.

In summary, A great afternoon of outdoor radio fun and already looking forward to next year.