From: fletcher@moho.uwyo.EDU (Walter Reid Fletcher)
Newsgroups: rec.radio.amateur.misc
Subject: Comments on Diamond X-500HNA for Repeater?
Date: 22 Jul 1992 23:01:55 -0700
Organization: UCSD Usenet Gateway
NNTP-Posting-Host: ucsd.edu

     Two 70cm repeaters have been running A/B comparisons between a Diamond
X-500HNA and a Celwave Storm Chief PD-458 (no beam tilt) for about a year here
in Laramie, WY.  Both are located at the same location with the antennas at
almost equal height (the Storm Chief is 5 feet lower) on the same tower.  The
active areas of both antennas rise completely clear of the top of the tower
structure.  Both repeaters have had each antenna connected to reduce
prejudiced conclusions due to varying receiver characteristics.

     The Celwave is a very heavy antenna.  Installation on outriggers (using a
gin pole) would be impossible without two people to manhandle it.  I had to
struggle a little to get it bolted to the tower itself.  The Diamond can be
held vertical by the bottom in just one hand for a brief time.

     The published gain figure for the Diamond was 11.7 db vs. 8 dbd for the
Celwave.  Celwave shows the gain reference in their catalog.  Since I have
never seen what the gain reference is for the Diamond, and judging from my
observations, I suspect the Diamond is referenced to a quarterwave or possibly
the elusive isotropic radiator.  The PD-458 is just short of 15 feet long.
The Diamond is a smidge over 17 feet long.

     The Celwave seems to outperform the Diamond when the repeater is accessed
by mobiles.  When on the fringe, a mobile can key the repeater with the Celwave
but not the Diamond.  In some spots where the repeater can be keyed but not
held with the Diamond, QSO's *can* be had with the Celwave.  Handhelds reveal
no appreciable difference in performance.  For a time one of the repeaters
used an older Andrew land-mobile antenna.  It was rated at approx 1 db less
gain than the Celwave.  There wasn't any discernible difference between the
Andrew and the Celwave.

     Both antennas have survived three (gusts to) 70 MPH winter wind storms.
The Celwave could not be seen to flex.  It's very rigid.  The Diamond was
bending 60 degrees from vertical repeatedly for several hours at a time.
A DB products DB224 was damaged during one of the storms.  The Diamond still
seems to work just fine on 2m and 70cm.  I haven't taken it down recently for
visual inspection because my back isn't up to the task.

     The climate is very dry so moisture (therefore corrosion) has not been
a major issue.  I do plan to replace the foam spacers with delren or teflon
and at some point silver solder the crimp joiners for the internal elements.

     I wouldn't consider using a Diamond for an antenna in a mountaintop
installation around here.  The winters would eventually kill Diamonds just like
they kill the commercial Ringos (CRX-150B).  They even ruin the big bucks
commercial stuff (Prodelin, Andrew, DB products, ...) with to much regularity.
I got the Celwave for a mountaintop (11,800 ft., rime ice, *BAD* winds).  I
have my doubts it will survive in that location more than a few years.  I hope
I'm surprised.

     I would purchase another Diamond given the right circumstances.  For a
repeater that many individuals rely on, I'd get the Celwave.

Reid, WB7CJO