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Author Topic: MFJ-270 Lightning Surge Protector  (Read 2843 times)
K5LPK
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Posts: 2




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« on: September 05, 2007, 08:51:57 PM »

The MFJ-270 Lightning Surge Protector has an (IN) and (Out) designator. Which sides goes towards the radio? Does it matter? I can not see anything special in its constructin that would require any specific polarization.

I have an e-mail out to MFJ, but read on their site where it takes up to 4 weeks to get a response.

Thanks in advance for any thoughts!
Leonard (K5LPK)
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K9KJM
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Posts: 2416




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« Reply #1 on: September 05, 2007, 10:25:29 PM »

This very same question was just asked on one of these forums.

Best answer:  RETURN the MFJ "protector" and buy a I.C.E. Or Polyphaser, And be aware that the actual device is a very very small part of the lightning protection system.

http://members.cox.net/pc-usa/station/ground0.htm

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KB9CRY
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« Reply #2 on: September 06, 2007, 05:43:04 AM »

I agree with Lon; return that and get a real protector from Polyphaser or ICE (Industrical Communication Engineers).

Anyway since you asked, the RF goes from your radio INto the IN side and then travels through the protector and leaves it on the OUT side and then heads towards your antenna.
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DXSHORTWAVE
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Posts: 12




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« Reply #3 on: September 06, 2007, 06:13:39 AM »

I've had much better performance and protection at my station with the Alpha Delta ATT3G50 protectors. The internal capacitors in 2 of my PolyPhasers failed at 800 watts CW so I threw them out. The ICE are over priced and don't do any better. In fact, at our commercial station we now use only Alpha Delta. Better know what you're getting. The MFJ are cheap and they are worth every penny.
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K5LPK
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« Reply #4 on: September 07, 2007, 05:16:00 PM »

All,

Thanks everyone for the information. K9KJM thanks for the informative link. It will take me a while to read through it all, but so far good info. I'll definately take the advice into consideraton for an upgrade.

As for my original question, here is the response from MFJ Enterprises - "truth is, doesn't matter. both meet in the middle at the gas discharge tube.  we say antenna in and out to rig but it could go either way"

Coincidentally this is the orientation I had mounted it.
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N3QD
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Posts: 26




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« Reply #5 on: September 07, 2007, 06:15:15 PM »

I would also suggest getting the ICE protectors (http://www.iceradioproducts.com/).  I've had them on my HF and VHF antennas for a few years now and never had an issue.  

Their main purpose is to protect your equipment from static electricity generated by blowing dust and precipitation rubbing against your antennas.  One always wonders if these devices really work, well I can tell you they do.  I live in southern New Mexico, and about a month ago we had an afternoon shower.  It happens that I just finished working on my 75M dipole when the shower came.  I picked up all my tools from the yard and reached over to plug the PL-259 back into my antenna switch box when ZAP, I got a pretty strong static discharge into my hand.  I dropped the connector to the ground from the surprise.  It took me a few seconds to realize what happened, and I grabbed the connector again figuring I discharged all the static between my grabbing it and it hitting the ground.  Well, I was wrong, ZAP again!  Not wanting to be the guy who touches a hot burner and says, "ouch that's hot", then repeats, I grabbed the coax, touched the connector to the base of my tower and quickly plugged it in.

So the moral of the story is I run a Ten-Tec Jupiter as my main rig.  It's an SDR and notorious for RF/Static issues causing it to act strangely.  I have never had a problem while using the ICE protectors.  With that said, any grade of protection is good, but have a look at the ICE website, read some of the tech documents and their theory of operation and make your own decision.

73,
Mike (N3QD)
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KG6AF
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Posts: 345




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« Reply #6 on: September 10, 2007, 04:48:35 PM »

I think the MFJ will work better on the second lightning strike, because the first strike should reflow the solder joints.
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N3QD
Member

Posts: 26




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« Reply #7 on: September 10, 2007, 06:01:39 PM »

Now that's funny!!  So if one runs an MFJ Tuner, no lightning  protection is recommended until after the first strike!

Mike (N3QD)
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