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Reviews Categories | Antenna parts, accessories, incl. baluns, hardware, etc. | MFJ-915 RF Isolator Help

Reviews Summary for MFJ-915 RF Isolator
MFJ-915 RF Isolator Reviews: 22 Average rating: 4.3/5 MSRP: $29.95
Description: 1:1 Current Balun to reduce stray RF on coax.
Product is in production.
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K6EB Rating: 3/5 Jul 5, 2017 12:26 Send this review to a friend
Quality Control  Time owned: 3 to 6 months
It does what it is supposed to do, but I have bought two of them and both times the screws have stripped and fell out after two or three months, and they filled with water in the winter. I'm going to try a different isolator this time around.
W2DL Rating: 5/5 May 22, 2017 11:57 Send this review to a friend
So far, so good  Time owned: 0 to 3 months
I have five dipole antennas in the hemlock canopy on my property. All of them have the Alpha Delta DELTA-C center insulator kits with coax connectors. Because of this, I looked for a balun that had coax connectors on both ends and could be connected to the Alpha Delta DELTA-C center insulator using a uhf double male adapter (Amphenol 83877). The Radiowavz B-11 ISO 1:1 balun does this, so I bought five. Three failed within a year. I've since replaced them with MFJ-915s which also have coax connnectors on both ends. The MFJ-915s appear to be built much better and they cost a hunk less. I plan to replace the remaining Radiowavz with MFJ-915s the next time those antennas require maintenance. If interested, see my review of the radiowavz B-11 ISO 1:1.
KK4GGL Rating: 1/5 Feb 13, 2017 21:38 Send this review to a friend
Poor workmanship  Time owned: 0 to 3 months
I bought 2 isolators directly from MFJ at a hamfest. When I got them home and tried to attach the coax, I found that the PL-259s would not fit on any of the 239s. The holes were off-center preventing the 259 to fully seat.
K6SDW Rating: 5/5 Aug 4, 2016 22:09 Send this review to a friend
2 years going  Time owned: more than 12 months
It works........I know, it's MFJ but really, it's worked for 2 years now
N5TQ Rating: 5/5 Aug 4, 2016 15:28 Send this review to a friend
Works like a charm  Time owned: 0 to 3 months
My solid state amp would trip off on the upper end of 40M despite a 1.1 VSWR. Probably because my coax run is about 40M also! But given my lot and antenna config, I really couldn't shorten it. So I put 2 of these in, one in the coax entry point in my shack, and another one close to where the coax enters the house. Bingo! But it took 2, the one in the shack alone didn't work by itself.
N6CIC Rating: 4/5 May 30, 2016 12:50 Send this review to a friend
Good when needed  Time owned: more than 12 months
When operating at of my antenna restricted house using a shortened loaded vertical (Buddistick) I was getting so much Rf in the shack that my radio would shut down, my keyer gave extra dits, and I could feel tingling on my fingers. I inserted the Rf isolator into the feedline after my tuner and the Rf problems were gone. However, when using a simple dipole cut for the band I was working, I found that the Rf Isolator "detuned" my antenna and my internal as well as external antenna tuners could not bring down the SWR. Removing the Rf Isolator solved that problem. So my conclusions are--it works very well in antenna configurations where needed, but for resonant antennas it may or may not be useful.
WB9OTX Rating: 5/5 Dec 30, 2015 19:22 Send this review to a friend
It did the trick  Time owned: 0 to 3 months
I am running a pair of 1/4 wave phased verticals. It seemed 90 % of the time I would receive lower reports than I gave out when using JT65 digital no matter what power I ran. I installed the MFJ-915 RF Isolator that I got used on QTH. I inserted it at the input of the relay box thinking I would just see if it helped, and did it ever - I now can run from 5 to 20 watts and get now as high or higher reports back. The RF on the feed line must have been throwing the pattern off on transmit. A very cheap fix. I did waterproof the connections with coax seal. I do run 1.5 KW on these antennas with SSB and the choke takes it with no problem. I'm not a big fan of MFJ but this is a winner.
K6HMD Rating: 1/5 Sep 26, 2015 17:58 Send this review to a friend
Didn't isolate anything  Time owned: 0 to 3 months
Maybe I misunderstood what this thing would do but I still had RF coming back on the shield with this installed near the antenna feed point. Jt-65 would crash such that my radio (IC-7600) was stuck in TX. Putting a couple loops on the feed line coax worked perfectly. This thing didn't stop anything.
M0KFO Rating: 5/5 Mar 30, 2015 08:19 Send this review to a friend
Does what it says on the tin  Time owned: 0 to 3 months
What's there to say. I have a G5RV, twin-coax, and was advised that it would useful to place one of these (1:1 current balun) between ladder line and the coax.

Seems to do the trick, a little less background noise and seems to match a little easier.

It's a straight forward item, stick inline and forget it. Seems overall well made. I don't use high power (for a UK Amateur, the power tops out at 400w, not that I use anywhere near that).

I think that some of the review differences between UK & US use for MFJ equipment, is our power is always well inside the limits.

Was about 35 from Radioworld (not many dealers stock this item).
KD4ONT Rating: 5/5 Jan 25, 2015 22:46 Send this review to a friend
An inexpensive place to start.  Time owned: 0 to 3 months
There are better "hand made custom" chokes out there. When I added this piece of hardware to my mobile station, it made a drastic improvement on the ten meter band! Better chokes would probably work more efficiently, but this unit quieted down my mobile receive big time! This reduced the qrm from my car and external sources to the point to where it was very noticeable! It won't eliminate all noise, but it will help. If this filter helps, for the price, then I would guess a better built unit would help more. Adding a device like this will change your swr readings. For me, it made the antenna appear longer. After deciding I wanted to keep it, I had to shorten my mobile antenna almost two inches. It is a cheap option to see if it quiets your receive. If it helps, then more expensive and better built options "should" work better. I still hear noise, but the average levels have dropped noticeably. I can't vouch for lower band performance, but for ten meters, it helped a lot!
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