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460 to 465 mobile antenna
- Thread starter 555
- Start date
Just my opinion.
I have played a lot with 477mhz cb equipment here in aus and I recommend getting something like an elevated feed antenna or ground independent antenna like what is on offer from RFI antennas.
You really need something with gain at those frequencies
I have played a lot with 477mhz cb equipment here in aus and I recommend getting something like an elevated feed antenna or ground independent antenna like what is on offer from RFI antennas.
You really need something with gain at those frequencies
Something like this
http://www.rfiemea.com/downloads/wireless/mobile-antennas/UHF-band/CD93-CD94.pdf
http://www.rfiemea.com/downloads/wireless/mobile-antennas/UHF-band/CD93-CD94.pdf
A 5/8 wave antenna would be best for line of sight. At that freq, it would be about ~7-8 inches for a 5/8 wave. There are all kinds of links on the net for making antennas. The formulas are very, very easy to get the dimensions you need for a 5/8. You can even make them out of metal coathangers; just so long as they are tuned to the right freq by length.
Ya just gotta remember this:
When you progressively go up in freq (in mhz), the 1/4 wave antenna gets shorter and shorter in length.
When you progressively go down in freq (in mhz); the 1/4 wave antenna gets longer and longer in length.
The length will change the usable tuned freq!
What about one of these?
Comet CSB-750A CSB-770A CSB-790A. Comet CSB-7500 CSB-7700 CSB-7900 Mobile Antenna
7.7 dbi isn't to shabby at 440MHz.
Comet CSB-750A CSB-770A CSB-790A. Comet CSB-7500 CSB-7700 CSB-7900 Mobile Antenna
7.7 dbi isn't to shabby at 440MHz.
Robb.....check your numbers again. Just off the top of my head I tbink a 1/4 wave is about 5 1/2 inches so a 5/8 wave would be just inder 14 inches. Then you have to make s matching network for it. MUCH easier to go with mad scientists idea. I use a Comet CA 2x4SR for 2m and 440 mhz. It is designed to cover tbose bands and MUCH more.I believe it is wide enough to cover 465 mhz without retuning.
Yupp....you are right....should be 2.5 times the length of a 1/4 wave. . . .
After thinking about it, and researching a little more perhaps I was wrong. It would appear the ca 2x4sr MAY be a better choice. There seems to be a question of the longevity of the commet 790a.
I have had mine for over a dozen years and although it was not used for a couple years it is still as good a performer as it ever was.It has taken a LOT of weather including massive amounts of highway salt. The black coating is chipped a bit in some places but nothing bad considering the amount of miles it has seen.I like that it stays rigid at highway speeds as well.Overall if anything happens to it I would buy another in a heartbeat.
I bought a CA2X4SR based on recommendations from the good Captain and a few others here. I must say, it is a performer, and the only antenna on my truck that doesn't whip around like a happy dogs tail in the freezing fog. Not super tall, and I can easily nail 2 meter repeaters at 75+ miles (depending on their elevation of course) and on 440 I get into a repeater on a mountain peak 112 miles south of me.
The CA2X4SR is a very nice antenna, but it doesn't qualify as a universal 'cure all' quite yet. It does have a couple'a 'faults' but nothing that isn't 'curable'.
It uses 'set-screws' and like anything that does, and that's subject to vibrations, they can work loose. So, make sure they haven't worked loose by checking them and re-tightening them when necessary.
They are not the most flexible antenna around! That's not always a 'fault' but you do have to be aware of it's stiffness and 'compensate' for it.
They only come in black, no designer-colors...rats!
They are purposely very 'broad banded', which means that they are fairly low 'Q', which isn't really a 'fault', but it isn't "gain packed" you know? (Yes, it does have reasonable gain.)
And they aren't rated for 40Kilowatts! Now THAT's a real disappointment, ain't it??
I have one in use and a 'spare'. I had a problem which I thought was with the original CA2X4SR I had so replaced it. Turns out it wasn't the antenna at all so I gotta spare. I use it on an HT, believe that or not. No, I wouldn't recommend it for that but with the proper adapter, and a 'rat-tail', it does just dandy on my front porch (when the temperature is above 65 degrees 'F'! I think it does good when it's cooler than that, but I don't).
- 'Doc
(If you are looking strictly for a 465 Mhz antenna, the CA2X4SR will work, but it's a bit of 'over-kill'.)
It uses 'set-screws' and like anything that does, and that's subject to vibrations, they can work loose. So, make sure they haven't worked loose by checking them and re-tightening them when necessary.
They are not the most flexible antenna around! That's not always a 'fault' but you do have to be aware of it's stiffness and 'compensate' for it.
They only come in black, no designer-colors...rats!
They are purposely very 'broad banded', which means that they are fairly low 'Q', which isn't really a 'fault', but it isn't "gain packed" you know? (Yes, it does have reasonable gain.)
And they aren't rated for 40Kilowatts! Now THAT's a real disappointment, ain't it??
I have one in use and a 'spare'. I had a problem which I thought was with the original CA2X4SR I had so replaced it. Turns out it wasn't the antenna at all so I gotta spare. I use it on an HT, believe that or not. No, I wouldn't recommend it for that but with the proper adapter, and a 'rat-tail', it does just dandy on my front porch (when the temperature is above 65 degrees 'F'! I think it does good when it's cooler than that, but I don't).
- 'Doc
(If you are looking strictly for a 465 Mhz antenna, the CA2X4SR will work, but it's a bit of 'over-kill'.)
Sounds like a winner to me.
I do wonder though as to why the 790a dosen't have a good quality rating? I have heard of them failing in just over a year's time.
I do wonder though as to why the 790a dosen't have a good quality rating? I have heard of them failing in just over a year's time.
