About a year ago, Radioddity sent me their HF-009 vertical antenna. At the time I didn’t have very high hopes of it, as their previous HF antennas were a bit underwhelming. But in using it I was pleasantly surprised and the HF-009 became a regular part of my portable kit.
But the antenna did have a couple of issues that were a bit aggravating, namely a permanently mounted spike on it’s base and a telescoping whip length that made tuning the 15 meter band hit or miss.
The great news is that their new HF-010 portable antenna fixed those issues and more. The Radioddity HF-010 is a portable HF vertical antenna with coverage between 6 and 80 meters and it is the subject of this week’s video: https://youtu.be/UU45u9FDYqg
Use this link and get a $15 discount when you shop at Radioddity
https://radioddity.refr.cc/default/u/KB9VBR
Rigexpert Stick 230 Analyzer: https://www.dxengineering.pxf.io/rEQxKD
What’s the deal with 80 meters?
If you watch the video, I talk about how I am unable to get a good match on the 80 meter band with the HF-010. The process to use the antenna on 80 meters, according to the instructions, is to set the whip to about 250 centimeters, disconnect the three ground radials, and entirely replace the tuning section with the fixed 3.5 MHz or 80 meter coil. Doing this should result in a match of about 1.5:1 at about 3.56 Mhz.
The problem is that I can’t get it to work.
I tried this antenna in three different locations. I used both the recommended setup and also experimented with variations. Each time I consistently got an SWR of 6:1 to 11:1 on the 80 meter band. The only time I was able to get an impedance match near 80 meters was to remove the common mode choke that I always keep on my feedline.
I’ll elaborate on the choke. When I left the choke on my 50 foot piece of RG8X coax, there was no dip at all on my meter at or near the 80 meter band. So I removed the choke, thinking that they were using the coax shield as a counterpoise. That created a dip of about 2.5:1, outside the band. Certainly not an ideal situation.
I then wondered if I could move the dip into the band. I added the tuning coil to the antenna and as I moved the slider on the coil, the dip shifted around in the band, but it still consistently stayed at about 2.5:1.
As you are reading this, you are wondering, how can this antenna operate without a ground network. That’s like half of your antenna system. The short answer is that it can’t. While there are some HF antennas that claim they don’t require a ground, they are deeply compromised in their function, especially on the low bands. Using your coax shield as a counterpoise is not a good solution as it introduces other problems into your system, namely RF interference into your transmitting equipment.
So I’m wondering, will using a mag mount (Radioddity says the antenna works with their big triple mag mount) or the ground spike have any effect on its 80m ability. I also wonder if adding more longer radials, so it has an effective ground network on that band, will help things out. Those ideas will have to wait for a warmer day.
Going into testing the antenna, I knew that 80 meters on a whip so short with a large loading coil would be a compromise. I figured if I would be able to get it work, the Q would be quite high and the bandwidth narrow. My hopes were for a good match on the bottom of the band for CW and digital operation where such narrow bandwidth is a feature and not a limitation, But alas, it wasn’t to be.
I’ll keep fiddling with the antenna, I want to make it work. It anyone has any ideas or positive results on the 80 meter band with their HF-010, please let me know.
Finishing Up
The Wisconsin QSO Party is this weekend on Sunday March 15. My original plans were to do a multi county roam with Dave, KZ9V, but he inadvertanly planned a trip on that weekend. My fallback was to plan out a three county roam with Christine driving. But the weather forecast doesn’t look promising, with predictions of 8 or more inches of snow Saturday night and into the Sunday of the contest. If the snow comes like they are saying, I will most likely be constrained to operating at home. Either way, look for me on the air.
I hope to get you in the log soon
Michael
KB9VBR
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