Tag Archives: VHF

IC-7100 now on VHF/UHF

It took long enough but I finally setup the IC-7100 for VHF/UHF use. The rig was programmed with the local repeater frequencies using RT-Systems programming software and a download from Repeater Book. Pretty straightforward overall. I should be able to use the IC-7100 on digital VHF nets run hear locally. There is a 6:30 net on Wednesdays through the repeater and a Simplex net on Thursdays at 7pm. I will still share the discone between this rig and the Yaesu FT-2900R.

One thing I noticed thus far is that he IC-7100 is hitting the repeaters in Harlingen and in South Padre Island. Not sure why this is but glad it seems to work.

Next up I’ll try and configure DStar.

2m Tropo Ducting is On!

Tropo Ducting is on this morning (8:30am) in our area on 2m. Check it out:


More Thoughts on The Flea Market HDTV Antenna

I dug around in a junk box and found a TV transformer and a length of 300 Ohm twin lead. Looking at the frequencies of the local TV channels, they are spread between 506 and 674 MHz UHF. Channel 5 is on 210Mhz VHF. I am thinking of cutting a 1/2 wavelength of the twin lead cut for 580MHz and making a folded dipole out of it. I’ll place the transformer right at the feedpoint. It strikes me that this would work better than the dipole I sourced from the flea market. I’ll build one of these and do an A vs. B test over the next few days.

I may also try a coaxial dipole made from RG-59 or RG-6 coax just for grins as well. That could end up being and even cheaper version that is at least tuned to the TV frequencies.

I figure the cost of making one of the dipoles is around $5 with the transformer being the bulk of the cost. The coaxial dipole would eliminate the need for a transformer. 300 Ohm twin lead for TV is getting hard to find but I am expecting decent performance.

The loop antenna makes some sense as being better than the dipole. It has some directivity, gain and it is better matched to the TV transformer.The crossed loops that are at the flea market would make sense in that they provide a more omnidirectional pattern (assuming that they are properly constructed).

Worked the local VHF Digital Net

W8WKE runs a Wednesday night digital net at 6pm on our local repeater system. I had been wanting to try it for sometime but did not have an interface for my VHF rig. Clifford, N5CEY, hooked me up with one of his Easy Digi USB interfaces for my Yaesu FT-2900R rig. I set up Fldigi on my radio laptop and set it all up to the rig. The net uses MT63-2000L protocol. When the net started I was able to start decoding the transmission without any issues. Unfortunately, I could not transmit. The Interface handles the PTT with the rig and appears to the PC as a serial COM port. I had both DTR and RTS enabled but nothing worked. Then I noticed a small enable check box above the COM setting. I enabled it and the transmit started working without a hitch. I have played with HF modes on DM780 so I need to now learn Fldigi. When I get back from my next business trip I plan to hook up the VHF antenna to the IC-7100 and try and work it from there with HRD. Working this net was a lot of fun and I am looking forward to trying it again.

My Ever Evolving Ham Shack…

I broke down this week and bought an ICOM 7100 rig this week. I have it installed with an A/B switch to the Yaesu FT-450D so that I can use both (though not at the same time). As usual, any changes to my shack wiring has caused issues with RFI. I have resolved most of these except I am noticing my HRD logbook locks up occasionally. This is a sweet rig. I have tested it on SSB on the HF bands and got the internal sound card modes working with PSK31 and JT65/JT9. It has some neat DSP features on Phone that really work. The automatic Notch filter seems to work on most birdies and the noise reduction works quite well. Still learning many of the features and doing some A vs B comparisons with the Yaesu. It has DSTAR built in so I will be trying to play with the local DSTAR repeater. Also looking forward to try and do some satellite work with it as well.


I asked Cliff, KF5INZ, for one of his Easy Digi interfaces for my FT-2900R so that I can work the weekly digital VHF net. Cliff makes these interfaces in Los Fresnos and ships them globally. I picked it up from him at the CHARRO meeting last Saturday and will likely start getting it setup in time for Wednesdays net. The 7100 has this capability built in but I will likely be using the Yaesu for for this purpose.



Finished the 2m Moxon Today

I finished up the 2m Moxon antenna today. I had bent the copper wire elements a few days ago after having straightened the #8 solid wire. Today just had to make some measurements, cut some PVC pipe, drill a few holes and solder up the feed line. All told a pretty quick build with the main issue taking time to get the measurements right. I called up W3OQ across town for a simplex radio check with the Moxon hooked up to my 5W Baofeng HT. I held it up, oriented vertically as high as I could reach and W3OQ reported full scale (13 bars) at his QTH. My 4W HT with the discone up about 12 feet scored 9 bars. Confirmed that there was directivity. Signal dropped to 5 bars on the backside. Looks like for an initial test it worked fine.

I am very impressed with how compact this antenna is. It is a rectangle only 29 inches by just less than 11 inches. Next steps will be to try simplex again with the antenna mounted up as high as I can get it on the painters pole. Here’s a picture of the completed Moxon

Photo Jul 16, 10 36 58 PM

VHF Yagi Ideas for Simplex Work

Some local hams have been experimenting with VHF simplex for communicating up and down the valley. The guy who usually leads these experiments is located in Brownsville and has his VHF vertical mounted on a 40 foot tower. He is able to communicate with other hams up and down the valley depending on the other hams configuration. I can communicate easily with him from my home QTH but I am deaf to all but one other local ham on simplex.

My VHF station is spartan at best. I use a 4W Baofeng handy talkie connected to a discone antenna that is up about 10 feet. I get no gain from the discone. This setup works real well for hitting the local repeater and for limited local simplex. I started thinking about the geographic location in respect to other stations in the valley and plotted the following map:


My QTH in Brownsville is in the lower right hand side of the map. The Rio Grande River is the US-Mexico border and the Gulf of Mexico is to the East. To cover the valley I only need a Beam width of about 126°. I started thinking about building a 2 element yagi vertically oriented and came up with the following azimuth pattern using EZNEC:


This antenna would give me a 133° beam width and a gain of 7.5dB over what I have now. My only concern is the rather low take off angle of the main lobe. Clearly the higher the better for this antenna but it looks like it would be a good starting point for experiments. Should be fairly simple to build from PVC and aluminum tubing. Will post more as I progress on actually building this.