Perry,

I run an anlysis on the last 76 manufacturing runs of LDF5 with the

parameters for analysis being L5NF connectors, at 140 feet, over the

frequncy range of 140 to 150 MHz. Your expected VSWR should be between 1.05

and 1.10.

Check your test equipement, verify that no water got into the line, and

verify the pin depths of the connectors. Attached is a graphic for N female

connectors that shows how to measure the position of the inner pin in

relationship to the outer body.

It is not too clear. The top picture is an N female interface. The dimension

to be measured goes from the top of the inner pin to the step inside the

barrel of the connector below the pin. You will be checking to make sure

that this dimesnion is between .187 and .207 inches. I hope this information

is helpful. Please let me know the outcome or if you need more help

-----Original Message-----

From: Perry Gwinn [mailto:pgwinn@mkchambers.com]

Sent: Tuesday, September 18, 2001 10:06 AM

To: Druszkowski, Dan

Subject: RE: WEBSITE: Technical Support

The frequency we tested at was 146.45, the antenna will be used for a

2-meter remote base, the connectors are L5NF Andrew connectors.

-----Original Message-----

From: Druszkowski, Dan [mailto:Dan.Druszkowski@andrew.com]

Sent: Tuesday, September 18, 2001 10:33 AM

To: 'pgwinn@mkchambers.com'

Subject: RE: WEBSITE: Technical Support

Perry,

There will defeinately be some level of VSWR in the transmission line. Let

me exactly what frequency you are operating at and what connectors you are

using, and I can give you an estimate of what the VSWR should typically be.

There are several factors that can affect the VSWR of a transmission line.

Throughout a transmission line (the cable, the connector) there will be

inevitable impedance mismatches that will contribute to VSWR. We design our

cable and with tight tolerance to keep these mismatches minimalized. The

attachment of the connectors themselves to the cable, if not done correctly

(ei; inner pin in too far or out to far) can contribute to a higher VSWR

level. I had talked to someone a couple of years back that had installed a

length of our 1 1/4" cable and was getting a VSWR of 1.9. We discovered a

connector attachment error (pin was recessed too far in the connector body

and was not making good contact with the test equipement it was mated to).

After correcting the pin depth, the VSWR of the line went down to 1.15.

Be sure as well, that the cable and connectors were dry. If the connectors

or the cable ends we exposed to the elements that is a definate contributor

to VSWR.

Also check to verify that the test equipement is properly calibrated and

that the adaptors and loads are in good condition. Most field calls we

receive typically end up being traced to adaptors or loads that have worn

out.

Again, let me know the operating frequency and the connectors being used and

I can tell you about what level of VSWR you should be seeing.

Regards

Dan Druskowski

Product Analyst

Heliax Products

[BEGIN FORM DATA]

Name :Perry Gwinn

Company :North Branch Amateur Radio Club

Address :PO Box 127

City :North Branch

State :MI

Zip :48461

Country :USA

Telephone :810-688-3650

Fax :

Email :pgwinn@mkchambers.com

Contact Via:Email

Sender's IP:4.18.142.242

[COMMENTS FOLLOW]

I have a situation and really don't know where to ask, so I thought I'd ask

you.

We just installed 140 feet of Andrew LDF5-50A hardline from the shack to a

side arm on the tower, antenna SWR pre-checked on the operating frequency at

1.5, after installing the antenna the SWR at the bottom was 3, so we put a

dummy load on the top of the hardline and checked just the hardline and SWR

was 1.5, should there be any SWR in the hardline alone?

Perry/KG8ID

[END FORM DATA]