Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Tunable Andrew Hardline Connector  (Read 535 times)
W8NYY
Member

Posts: 38


WWW

Ignore
« on: April 30, 2008, 06:56:15 AM »

Our 440 repeater moved to a new site and the 7/8" hardline is pressurized using an Andrew H5NF-T tunable connector. Unfortunately it's attenuating our frequency (443.5125) and needs to be retuned. We cannot find the instructions anywhere on how to retuned the connector and emails to Andrew have gone unanswered. You can see the connector at http://awapps.commscope.com/catalog/product_details.aspx?id=9628#
Hopefully someone here knows these connectors and can point us to the instructions. Thanks & 73,
Bob, W8NYY
Logged
WT0A
Member

Posts: 922




Ignore
« Reply #1 on: April 30, 2008, 08:19:17 AM »

It appears to be speced at 2GHX range.
Glen
Logged
K6AER
Member

Posts: 3535




Ignore
« Reply #2 on: April 30, 2008, 08:50:38 AM »

The connector you have is tunable in the 2.4 to 3 GHz range. I was a popular feed connector for older MMDS transmission systems and was located at the base feed point inside the head end. I will have no effect at 440 MHz. I suspect it was used because it was lying around.

As for it detuning your signal at 440 MHz the lumped capacitance in the tuning stubs is very slight and in the order of a few pF per stub. Just back the tuning stubs all the way out.
Logged
W8NYY
Member

Posts: 38


WWW

Ignore
« Reply #3 on: April 30, 2008, 08:56:47 AM »

We'll give that a try.  Thanks!
Logged
W8JI
Member

Posts: 9296


WWW

Ignore
« Reply #4 on: May 01, 2008, 04:55:50 AM »

Bob,

If that connector behaves like the similar style connectors I have here you can adjust the tuning forever and it won't affect 430MHz very much at all. The tuning only makes a slight change way up in the GHz region! It gives a very slight SWR change up around 2GHz with an increasing effect as you go up in frequency.

Perhaps you have something else wrong in the installation.

Was this an existing cable that you are allowed to use?? Is it an air dielectric cable and has it always been under air pressure with dry air?

73 Tom
Logged
W8NYY
Member

Posts: 38


WWW

Ignore
« Reply #5 on: May 01, 2008, 05:20:59 AM »

Hi Tom,
Yes, the coax was in place on the Wood County OH owned tower which they were so good to rent us (ARES) space at a dollar a year. When we put the 440 antenna up we pressurized the cable which had been abandoned for a period of time and the cable held the pressure. One of our members, an engineer with the local ABC affiliate checked out the line with his equipment and all seemed to check out OK with the acception of the attenuation of the signal. Our first thought would be to replace the tunable connector with a gas barrier Andrew HJ5-50 air dielectric cable connector but before we spent the money we wanted to rule out the connector and determine if in fact it was the issue. If backing out the tuning stubs makes no difference then we may in fact have another issue such as you're eluding to.
By the way, your name comes up often in my circle of friends and "old hams" here in NW Ohio. Of course they say only good things. Hi hi.
Thanks.
Bob, w8nyy
Logged
W8JI
Member

Posts: 9296


WWW

Ignore
« Reply #6 on: May 02, 2008, 03:59:41 AM »

Thanks Bob,

I grew up in Northwood. I used to come down to BG and hang around with a kid named Bill Rhode. He was my lab partner in electronics lab.

While I have not had that particular connector, I have had similar connectors. They pass dc through the upper limit of my test gear 6GHz without a problem.

The little adjustments on the connectors I have only change the return loss a little bit up at the very high frequency end. They are very fine adjustments that barely change the SWR, and only then at the upper end.


You could have a bad connection someplace in the cable or antenna system, or the coax might be filled with water. If they left the cable unpressurized for a long period of time it will eventually collect water in any low spots. This is especially a problem if the cable has a horizontal run or a drip loop at the bottom.

The water normally won't hurt the cable performance below a few GHz **if you can dry it out**. Drying it can be difficult or time consuming though! You'd have to open the bottom to drain the water and then slightly vent the top and dehydrate the line for a long period under pressure with dry air.

The only other problem could be a bad connection someplace or a bad antenna.

You might want to send someone up the tower with a dummy load and power meter, or use a TDR to look at the cable. I'd look close for water or other problems before changing the connector.

Air lines often won't last long without pressure, but nearly all of them can be saved if you get the water back out.

73 Tom




Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!