Thanks Allen.
All coax harness measurements are center of moldings or splices.
The dipoles are supposed to be standard db224a elements. I will have to measure
them and get back to you on that.
All connectors are N type.
Thanks again
Norm
----- Original Message -----
From: Repeater-Builder@yahoogroups.com <Repeater-Builder@yahoogroups.com>
To: Repeater-Builder@yahoogroups.com <Repeater-Builder@yahoogroups.com>
Sent: Thu Feb 18 08:49:47 2010
Subject: RE: [Repeater-Builder] DB224A new harness
Norm
I need you to do two more things:
1) Tell me where the measurements of the lengths of the coax were made to,
were they to the edge of the molded tee block, or to the center of the block,
and at the splice to the different coax cables, was the measurement to the
center of the splice or at the edge of the shrink tubing?
2) I used Z measured data from a DB 224A (for the 150-162 range) in my
inventory, of the physical dimensions of the dipole. Would you confirm the
dipole dimensions of the antenna you are using, everything including the
spacing to the mtg pipe, the overall length, the length from the center
mounting bracket to each end of the dipole and the dimension of the center to
center of the folded section. I want to confirm that I am using correct data in
my calculations. Only one dipole dims. are necessary. A dwg would be nice.
From first go around the Smith Chart, it appears that to use or modify the O.C.
stub to optimize the impedance matching for use at 144-148 Mhz may be unwise.
I'm leaning towards adding a Tee adapter with stub at the feed point connector,
and if necessary modifying the length of the 106.5", 50 Ohm feed line coax. If
you somehow modify the O.C. stub and your results are worse, then you have
essentially destroyed the matching harness usefulness. Please also advise the
type of connector used at the feed-point, "N" or "UHF".
WA9ZZU
--- On Wed, 2/17/10, NORM KNAPP <nkn...@twowayradio.net> wrote:
From: NORM KNAPP <nkn...@twowayradio.net>
Subject: RE: [Repeater-Builder] DB224A new harness
To: Repeater-Builder@yahoogroups.com
Date: Wednesday, February 17, 2010, 10:35 PM
The unknown coax type is/was VB-83 (35 ohm). The VB-8 is of course 50
ohm and the VB-11 is 75 ohm.
I hope that is the info you needed. It would be great if you could
figure out what the open stub is for and can we use that for adjustments. If
you need more info, let me know.
73
Norm
____________ _________ _________ __
From: Repeater-Builder@ yahoogroups. com
<http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com>
on behalf of allan crites
Sent: Wed 2/17/2010 9:29 PM
To: Repeater-Builder@ yahoogroups. com
<http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com>
Subject: RE: [Repeater-Builder] DB224A new harness
I tried to work backwards on a Smith Chart from the dipole to the 1/2
WL O.C. stub to determine a reason for the stub but it appears the unknown coax
types are causing erroneous and confusing answers.
Can you confirm the coax types shown on your diagram?
a.
--- On Wed, 2/17/10, NORM KNAPP <nkn...@twowayradio. net
<http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net> > wrote:
From: NORM KNAPP <nkn...@twowayradio. net
<http://us.mc822.mail.yahoo.com/mc/compose?to=nknapp%40twowayradio.net> >
Subject: RE: [Repeater-Builder] DB224A new harness
To: Repeater-Builder@ yahoogroups. com
<http://us.mc822.mail.yahoo.com/mc/compose?to=Repeater-Builder%40yahoogroups.com>
Date: Wednesday, February 17, 2010, 3:57 PM
I got the harnesses at no charge from Andrew. I contacted customer
support and told them I had 3 fairly new DB224's (2 a models and a b model)
that had water intrusion/contamina tion in the harness where they were
supposedly seal by the factory. I offered pictures and they accepted. Upon
seeing the photos they asked that I give them serial numbers and requested I
send the defective harnesses to them. I did and they offered and I accepted
replacement harnesses.
The two db224's that I have (personally) are the A models. The B model
belongs to my shop. I often end up with abandoned and or defective db224's and
other antennas as I work for a two way land mobile dealer/shop. Unfortunately,
I have yet to get any DB224e's or any DB304's, just tons of DB224a's and an
occasional DB224b.
Hats off to Andrew for shipping me free replacement harnesses. I am
still gonna ScotchKote those moldings regaurdelss.
If you look at the attached photoes from my initial post, you will see
that the open 25" VB-8 (50 ohm) stub is 12.5" from the "T" where the top half
and bottom halves of the harness come together, down the main feed to the
hardline (or whatever you feed the antenna with).
Last night I connected the Sitemaster up again and I noticed the the
SWR will come down some when I firmly secure the harness to the mast with the
metal tape. How far down remains to be seen. I will keep you posted.
73 and thanks!
de N5NPO
Norm
