Mobile 10m Antenna Testing

[Robb]

Had the chance today for AudioShockwav/Jeff to test out some of his mobile antennas with me this morning. Jeff sent me a PM and asked him if I could help him with this test. Spur of the moment deal, Jeff has a spot where he can reach me whenever he wants. This is -by no means- a scientific test. Just a seat-of-the-pants test so that some simple evaluations could be made

I was on my base station, and Jeff was running from his mobile. The distance between us was roughly 104 miles/straight line with a 145 miles/3 hrs driving distance with Mt. Hamilton (4196 feet high) between us - I might add. Here is a map that can give you an idea. Jeff was talking from a ~2300 ft elevation just N of Catheys Valley, CA; and I was at 197 ft in Cupertino, CA.

I was running ~45 watts/SSB into an Imax 2000 and using the FlexRadio SDR-1000. Jeff was running a RCI-2950, a ~500 watt amp, and four different antennas.

These antenna lengths were primarily designed for CB/11m use:

1) Francis AMAZER @ 96 in/length (Francis no longer makes this model)
2) Francis AMAZER @ 93 in/length (?) (trimmed from a 96 in)
3) Predator 10K w/27 in/lower shaft (overall length unknown)
4) Predator 10K w/22 in/lower shaft (overall length unknown)

I had a fair idea that these Francis AMAZER antennas would be fairly wide-banded. But I must say that I was surprised that the Predator 10k/27 in base worked so well on 12m too. On the SSB portion of 10m, the Predator 10k/27 in base also did fine. Thought the AMAZER worked outstanding on FM/29.600mhz; but the Predator 10k's didn't fair as well.

Here are some recordings of our conversations on 28.455mhz USB/10m and 24.985mhz USB/12m . The content is self-explanatory and are in a .mp3 file format. If you need to download a player for these files, try VLC Media Player (freeware): VideoLAN - VLC: Official site - Free multimedia solutions for all OS!

 

[Robb]

More Audio Samples. . .

Here are the rest of the sound files.

Jeff will fill in some blanks from his perspective.

 

[AudioShockwav]

Here are the measurement`s on the antennas.

Full Size Francis is 96 inches long, just as it came from the package.

The Shortened Francis 93 1/2 inches long, I had removed 2 1/2 inches from it for running a little better SWR on Ten Meters.

The P 10k that I call the Short Shaft has a 22 inch shaft below the coil, with a over all length of 81 inches.


The P 10k that I call the long shaft has a 27 inch shaft below the coil......this antenna also has a Quick disconnect on the bottom that stays with it, it is 2 inches long, so in actual measurement with the Q/D it is 29 Inches from the mount to the bottom of the coil.
The Overall length of the antenna with Q/D is 87 inches

All of these antennas were used today on both Ten and Twelve Meters and at all times the SWR was under 3 on any of them
Power out was @ 320 +/- about 10 watts
Radio was a RCI 2950DX, Texas Star Amp DX 500V, Aries A-SWR 460 Digital Power/SWR Meter.
The Antenna Mount it a Pro Com Mount, that is mounted at the left rear corner of the bed, level with the top of the bed.
We also worked 10 AM for a while on 29.200 and then switched to Ten FM Simplex @ 29.600
Ten Meter SSB was on 28.455 USB and 12 Meter`s was at the very top of the band @ 24.985 USB.
About 1 s unit in Rx over them all tells me that any of them will work good on these 2 bands.

I really did not intend to include the cut down Francis antenna when i went up there.....but at the last min i threw it in the back of the truck.

I have always liked the Francis 96" whips, and the P10k with the 22" shaft has always been a good antenna as well, and today it surprised me that it would cover the band-width it did.
Rob`s Flex Radio sounded great on my end, and he was running much less power than I was.
Thanks for "rolling the water-gate" and your time on the Air today Rob, I appreciate it.

73
Jeff

 

[Robb]

Hey; it was fun Jeff.
Used the record on-air feature of the Flex; had to convert the 192khz sample rate files to 48khz - which was a breeze!

I had close to 6 S-units of static today (not that unusual for where I live) - and you can hear it in the recordings.

First time I used the Flex on FM. Usually FM static is kinda harsh on most other radios; but was extremely smooth on the Flex. Jeff told me that FM sounded fantastic on his end (his own words BTW). For some reason that I haven't yet determined why/how the set filters went from 4khz wide to 6khz wide on FM. More reading for me to do - I guess. Still whittling down the operating manual; it is large! Not sure how Jeff rated this radio on AM IIRC.

Of course, I used the internal antenna tuner (a LDG-100) on the Imax to clean up the SWR to its lowest points on those bands used. Didn't need too much to clean up the impedance mismatch.

The AMAZER antenna sounded awesome on FM too. It was the only antenna that had Jeff at full quieting. I used 25/19 watts on FM respectively with full quieting from Jeff's reports. Too bad that Francis no longer makes those 96 inch whips. They should! Bet they would sell a bunch. Great bandwidth. Jeff wasn't using an antenna tuner; IIRC the usable width was close to 4mhz.

Considering the usable bandwidth of the Predator 10k; I think it is a fine antenna and should be considered for any Amateur that wants to cover both 12m and a big chunk of the 10m bands. Very long overall length antenna; very efficient. They are very well built, use excellent material, and are fairly inexpensive (~$65) for what you get - IMO . . .

 

[gamegetter]

thanks for the time and effort guys.

Audio, I have some NOS Francis, but they are not the Amazers, they are the wheeler dealers,,,The difference between the two is supposed to be the Amazer has 3 wires wound around the fiberglass while the wheeler dealer has only one.

Is that what you have observed while cutting the Amazer and second question:
Did you trim a little at a time to get what you wanted or do it in bigger cuts?

Just wondering thanks again.

 

[AudioShockwav]

Cutting down 2 1/2 inches I found 3 wires, inside the fiberglass.
Cut down about 1/2 at a time.
73
Jeff

 

[AudioShockwav]

Chris, here is the thread.


73
Jeff