[TowerTalk] XM-240 Tuning Issues

[Greg Clark]

Hi Folks,

Here is what I found and THANKS to all who replied via the reflector and direct.

Several comments came out about my stating there is a "matching network".  That's Cuscraft's nomenclature, not mine.  It's a 1:1 balun, no more.

The problem appears to be some type of broadcast overload on the handheld analyzer.  I'm at a new QTH and I have some 1500ft TV broadcast towers about 4 miles to the south, I'm guessing that's the issue?  Upon getting some LMR400 to the tower and putting some real RF into the antenna from the shack, all appears to be good.  I have the antenna flat up aroud 7.060.  

Thanks,

Greg
K9IG


----- Original Message ----
From: wa5zup <wa5zup at msn.com>
To: towertalk at contesting.com
Sent: Sunday, April 6, 2008 8:35:49 AM
Subject: Re: [TowerTalk] XM-240 Tuning Issues

I thought the XM240 balun was a 1:1?
The XM240 balun they supply is just teflon coax wound (4 or 5 turns I
think)around three ferrite cores
The older CC antennas used a coax coil balun and grounded the reflector.
John
Wa5zup

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Doug Renwick
Sent: Saturday, April 05, 2008 9:58 PM
To: 'Greg Clark'; towertalk at contesting.com
Subject: Re: [TowerTalk] XM-240 Tuning Issues

Greg,

Is this a brand new CC antenna?

Something is wrong with the SWR ... you should see 1.4 or 1.5 at 7.062
MHz which is correct.

The reflector on the XM is NOT grounded to the boom.

The matching network you are referring to is probably the CC balun.  I
would replace it with an Array Solutions AS-25-1 2:1 balun.

Doug

"Those Island days are always on my mind,
Someday I'm going to leave it all behind."

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Greg Clark
Sent: April 5, 2008 7:20 AM
To: towertalk at contesting.com
Subject: [TowerTalk] XM-240 Tuning Issues

Just got a CC XM-240 together and on the tower.  I'm having some tuning
issues.  There are CW, MID and SSB settings on the elements and I split
the difference per some of the other posts that I have seen between CW
and MID.  At 80ft and using an MFJ-259B, the best I see is about 2.5 SWR
at 7.062Mhz.  I see no other dips.

Any tips?

Coils looked good with the exception of 1.  The outward facing opening
on one LCA was larger than the others and was too large for the element
tip.  I made an aluminum sleeve so that the tip would fit.  

I'll be bringing the antenna back down today or Sunday to go-over.  BTW,
I am using the CC supplied matching network.

Thanks,

Greg
K9IG
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