I've had a couple commet antennas including the one I have up currently for 
900 MHz and they're exactly the same as the diamond in that aspect. Maybe 
not all of them are but the 2 I've had over the years were/are. I don't have 
the dual bander anymore, I sold that but the 900 MHz one is still up and 
going. Anyway though, both of them had the sleeve like the diamonds to and 
the one small bolt holding the antenna in the sleeve. In fact, looking at 
them side by side you'd never know the difference in brand. I also have a 
tram UHF antenna I used to use on GMRS, right now it's in the shed because I 
don't have the GMRS license anymore and 70CM is dead around here or I could 
easily retune it for there but that is also exactly the same mounting system 
and to my knowledge I've never lost one of those bolts though I have heard 
of other people having that problem. I haven't checked the diamond X50 in a 
couple years so it may have happened to that one but I know it's still up 
there anyway. I have a diamond X30 up as well for my scanner which was 
completely rebuilt but that just went up recently and it's very low so 
shouldn't get much wind or anything.
----- Original Message ----- 
From: "Butch Bussen" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 28, 2015 6:19 PM
Subject: Re: plans for high gain 2m 70cm antenna


>I recently bought a diamond 210 and when we got it put together, I found
> diamond has what I consider a main design flaw.  The last dual bander I
> had up was a comet, I don't recall the model.  I didn't realize until I
> got this last diamond.  I'll try and describe the problem.  At the
> bottom of the diamond right below the radials is a round piece about 2
> inches long and at the bottom of this is where the coax connects.  This
> piece sets inside a piece of tubing a foot and a half long and this
> piece is where the mounting hardware goes that mounts the antenna to the
> mast.  All that holds that hole top part of the antenna in place is a
> small bolt that goes through a hole in the pipe and screws into the
> round piece that slides inside.  Hope that makes sense.  The problem is
> (this happened to me 2 or 3 times in Vegas, is vibration shakes this
> bolt out and then the antenna just wobbles around inside this tubing.
> If they insist on mounting it this way, there should be bolts.  What I
> did to fix my uhf one in vegas was to cut an x or cross in the outside
> tubing with a hack saw and put on a hose clamp. This held the bolt in
> and also compressed the tubing against the inside part.  A poor design
> as far as I'm concerned.  Commit is totally different and much better.
> I'll never buy another diamond.
> 73
> Butch
> WA0VJR
> Node 3148
> Wallace, ks.
>
>
> On Tue, 28 Apr 2015, Colin McDonald wrote:
>
>> I've pulled a couple of these apart.
>> There are multiple matching coils, loading coils and various element
>> arrangements all the way up the antenna.
>> It's not a simple thing to build.
>> far easier to build a yaggie or quad for those bands.
>> I expect it would also be more expensive to build something like the
>> x200/300 as well than it is to buy one.
>>
>> 73
>> Colin, V A6BKX
>> -----Original Message-----
>> From: Neil k8it
>> Sent: Tuesday, April 28, 2015 2:24 PM
>> To: [log in to unmask]
>> Subject: Re: plans for high gain 2m 70cm antenna
>>
>> I have been thinking of building a base station 2m and 70cm antenna. I 
>> like
>> the diamond x-200a or x-300a designs but would like to try building one
>> myself. the antennas are rated at 6 to 6.5 dB on 2m and 8 to 9.5 dB on 
>> 70cm.
>> But does anybody have dimensions of this type of antenna? I found several
>> J-pole designs but no 5/8 wave collinear designs with radials similar to 
>> the
>> Diamond x-200A or x-300A antennas.
>> Anybody have any thoughts?
>>
>> Would a 8 foot center element (two 5/8 waves in series simply work? would 
>> it
>> match to 50 ohm coax? will it match on 70cm?
>>
>> thanks
>> 73 Neil k8it
>>
>>