Hello Allan
As you note it would take a good deal of work to go from 154 to 220Mhz.
Yes the loops would have to be shortened and the harness would have to be be
reworked-shortened. This would be easier than changing to 144Mhz. I have done
this twice in the past. 73 de Tom Manning
----- Original Message -----
From: allan crites
To: [email protected]
Sent: Thursday, February 18, 2010 5:47 PM
Subject: Re: [Repeater-Builder] DB224A new harness
Tom
I would certainly be interested in knowing just how a 150-162 MHz DB224
could be "easily be modified to cover 220". The dipoles would need to be
physically shortened and the matching harness would need to be completely
redesigned.
What magic do you have in your bag of tricks to manage this?
Allan Crites WA9ZZU
--- On Thu, 2/18/10, Tom Manning <[email protected]> wrote:
From: Tom Manning <[email protected]>
Subject: Re: [Repeater-Builder] DB224A new harness
To: [email protected]
Date: Thursday, February 18, 2010, 4:58 PM
Hello Andrew and Norm
If you are trying to figure out the lengths needed for 144-148Mhz
I can measure what you need to know but not in a hurry. I have a DB products
antenna that is cut for the two meter band that I ordered from DB Products
about 10 years ago. What I need to know is the measurements for 220Mhz. I
also have several DB224a's that have been removed due to problems. These could
easily be modified to cover 220Mhz. 73 de Tom Manning, AF4UG
----- Original Message -----
From: NORM KNAPP
To: Repeater-Builder@ yahoogroups. com
Sent: Wednesday, February 17, 2010 10:35 PM
Subject: RE: [Repeater-Builder] DB224A new harness
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 on behalf of allan crites
Sent: Wed 2/17/2010 9:29 PM
To: Repeater-Builder@ yahoogroups. 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> wrote:
From: NORM KNAPP <nkn...@twowayradio. net>
Subject: RE: [Repeater-Builder] DB224A new harness
To: Repeater-Builder@ yahoogroups. 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
