/06 Thu AM 06:32:31 CST
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: DB 212-2 Harness info.
JK,
The coaxial sections coming off each antenna element is 35 Ohm coax at odd
multiples of 1/4 wave length.
What this does with antenna element at 50 Ohms
JK,
The coaxial sections coming off each antenna element is 35 Ohm coax at odd
multiples of 1/4 wave length.
What this does with antenna element at 50 Ohms then 1/4 wl down the 35 Ohm
cable it looks close to 100 Ohms looking into this cable. Then you take 2 of
these ant elements/35 Ohm coax
What this does with antenna element at 50 Ohms then 1/4 wl
down the 35 Ohm cable it looks close to 100 Ohms looking into
this cable.
No, that's not right. If the element were 50 ohms and you attached 1/4 wave
of 35 ohm cable, you would transform it down to 25 ohms, not up to 100 ohms.
You
- Original Message -
From: Jeff DePolo [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Thursday, March 06, 2008 11:19 AM
Subject: RE: [Repeater-Builder] Re: DB 212-2 Harness info.
What this does with antenna element at 50 Ohms then 1/4 wl
down the 35 Ohm cable it looks close to 100
be simpler since only one cable
critical length.
73, ron, n9ee/r
From: Chuck Kelsey [EMAIL PROTECTED]
Date: 2008/03/06 Thu AM 10:36:40 CST
To: Repeater-Builder@yahoogroups.com
Subject: Re: [Repeater-Builder] Re: DB 212-2 Harness info.
I agree with Jeff. The lines to each element
Hey Guys'
Why don't you Just post a diagram with the pertinant information on on the RB
site. A picture is with a a thousand words.( and numerous back and forth
emails) I would be interested in seeing a simple solution for a new harness
for all the DB di-pole antennas using commonly
Yes, on a DB212 antenna, the element is 50-ohms and has a 50-ohm pigtail.
When you parallel two of these antennas, the feedpoint at the tee becomes 25
ohms. The 35-ohm 1/wave transformer brings things back to 50-ohms.
Caution - other DB antenna elements are NOT at 50-ohms. We are talking about
Sorry, typo should have said the 35-ohm 1/4-wave transformer
- Original Message -
From: Chuck Kelsey [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Thursday, March 06, 2008 6:03 PM
Subject: Re: [Repeater-Builder] Re: DB 212-2 Harness info.
Yes, on a DB212
Jeff,
As some have stated the coax coming off the DB212-2 dipoles is 50 Ohms. These
two are connected to a T connector and these 2 will be in parallel making 25
Ohms.
The 35 Ohm coax, special for this application, forms what is called a coaxial
transformer. Transformers can be used to
Yes, that is correct.
Chuck
WB2EDV
- Original Message -
From: John Everson [EMAIL PROTECTED]
To: Repeater-Builder@yahoogroups.com
Sent: Wednesday, March 05, 2008 10:12 AM
Subject: [Repeater-Builder] Re: DB 212-2 Harness info.
--- In Repeater-Builder@yahoogroups.com, Chuck Kelsey
You are correct. It was a poor choice of words on my part. I
understand the theory of velocity factor. I am still not sure about
the lengths involved with the harness. If the 50 ohm sections from
the loops to the tee can be any length, (as long as they are the
same) doesn't that affect
Your logic is right, but your assumption that the feedpoint Z
of each bay is
200 ohms is wrong. A folded dipole in free space is close to
200 ohms when
fed at the open center of one side, but the dipoles in the DB
array are
close-spaced to the mast which drops the feed Z to close to
The DB-212 is a 50-ohm antenna with a 50-ohm feedline. You are combining two
50-ohm antennas at the tee which makes it 25-ohms. A section of 35-ohm cable
brings it back to 50-ohms.
Chuck
WB2EDV
- Original Message -
From: John Everson [EMAIL PROTECTED]
To:
13 matches
Mail list logo
