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MFJ-915 RF Line Isolator

whiteastro

Sr. Member
Feb 22, 2019
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Need help understanding this object that came in the mail addressed to me from a ham shop in TN. And I didn't order this thing either but I was waiting for a MFJ-918 1.1 current Balun which came the next day. This MFJ-915 in suppose to be hooked between the radio and the antenna and it sounds like it is for mobile radio systems. HELP Anybody ever use this thing and if so what is the benefit of using it and is it meant for 11 meter radio? I'm all ears !
 

MFJ-915 RF Isolators are 1:1 ferrite chokes designed to be placed in line with 50-Ohm coax. These RF Isolators are effective from 1.8 to 30 MHz at full SSB legal power. They were designed to improve the performance of all amateur stations, fixed or mobile.

MFJ RF isolators reduce or eliminate stray RF often found on coax shields. If strong enough, this current may cause RF burns or other problems with electronic equipment in ham shacks and vehicles. Stray RF also results in a loss of radiated power from the antenna, which will cause a reduction in radiated signal strength. Use of MFJ-915 RF Isolators will increase the efficiency of all HF amateur stations.

These RF Isolators are made up of 50 Ferrite Core Beads, placed onto a 13-inch piece of RG-303 coax. The coax and SO-239 connectors have PTFE insulation which extends the life of the product. The entire assembly is enclosed in schedule 40 PVC pipe for maximum strength and protection.

If you have an RFI problem in your shack, then one of these MFJ-915 RF Isolators will help.
 
Here is the difference in the way they connect.
 

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Sorry haven't tried them yet. Still in the get ready for winter mode.
Whiteastro, it is time for cold weather, so if you ever think about my question when the weather gets better, leave us a post/thread with your results, OK?

Also give us some words about how and where you use them.

I'm 84, and I need all the good help I can get.

73' and God Bless,

Eddie - Marconi - Grampa on my radio.:)
 
Last edited:
  • Like
Reactions: whiteastro
Whiteastro, it is time for cold weather, so if you ever think about my question when the weather gets better, leave us a post/thread with your results, OK?

Also give us some words about how and where you use them.

I'm 84, and I need all the good help I can get.

73' and God Bless,

Eddie - Marconi - Grampa on my radio.:)
Yes I will when I get more chance to deal with my radios. I live alone and tend this and another property alone so every year it takes time to switch and prep equipment and fall clean up. Arthritis also slows you down. LOL I don't get as much radio time as I would like, but pretty soon Mother Nature will force me in the house until Old Man Winter forces me back outside to clean up the White Stuff. It's not bad enough I do my own property but I have a elderly Mom and 2 Elderly sisters who live on the other side of town who need help Always. The MFJ-915 will get installed in my car soon to see if it helps with DX. The MFJ-918 is for my garage dipole project and that will take more time to get at. 73s Happy DXing
 

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