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Reviews Categories | Filters, RF: bandpass, duplexer, lowpass, highpass, RFI/EMI | T-4 line isolators Help

Reviews Summary for T-4 line isolators
T-4 line isolators Reviews: 11 Average rating: 4.5/5 MSRP: $$35.00-$50.00
Description: T-4 line isolator is an asymmetrical current type unbalanced to unbalanced [UNUN] device that acts as an rf choke to any rf flowing along the outer surface of a coaxial cable, without affecting the signalcarried by the cable.
Product is in production.
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K8DXX Rating: 5/5 Aug 25, 2016 14:15 Send this review to a friend
Pretty Good  Time owned: more than 12 months
I have owned 3-4 of these line isolators, installing them as a general precaution around my
former QTH. After changing locations, antennas, etc. I put up an off center fed dipole including a feed point RF choke made of 12 turns of RG8X around a 3 inch ferrite doughnut. Stray RF didn't bother my IC 7300 but disabled my Flex 6300 while running my ALS 600 amp. Installing one T4G took care of the problem. I was surprised but pleased.
K7MM Rating: 5/5 Mar 8, 2014 18:09 Send this review to a friend
Wow! No More RF Distortion in my Audio!  Time owned: 0 to 3 months
I installed a T4-500 at the transceiver feed to my QSK Master input. I installed a T4-G at my antenna cable that goes outside my hamshack. The connection from my Amp Supply LK-500ZA goes through the QSK Master, to the Bird peak-reading wattmeter, through the Alpha Delta antenna switch to the T4-G.

I could not use my amplifier on 80-m SSB before the line isolators. Now, beautiful, clean audio! There is no more distortion from RF feeding into my audio.

Another plus--my computer interference is gone. My 24/7 JNOS BBS used to go down every time I transmitted with the amplifier. Now, no more having to reboot my Linux machine!

These should be mandatory for every high-power (QRO) installation.
W4KVW Rating: 5/5 Mar 4, 2013 08:55 Send this review to a friend
GREAT Product! }:>)  Time owned: more than 12 months
Does an awesome job on my 160 meter half sloper.I could NOT ask for more & the price was reasonable.
Can't argue with success! {:>)

K5WRK Rating: 2/5 Dec 25, 2012 00:46 Send this review to a friend
NOT THIS TIME  Time owned: 0 to 3 months
K2HAT Rating: 5/5 Aug 3, 2010 03:33 Send this review to a friend
I am using 2, one before my amp, one after, A+  Time owned: more than 12 months

I fixed my RFI problem,{when adding 5 snap on ferrites didn't help;}
with 2 Radio Works Line Isolator's. :)

One is between the FT-920 and the FL 2100B, and the other is
inline between the FL-2100B and my antenna tuner.

Look under RFI suppresion on the web page.

When trying to solve the RFI problem, I upgraded my coax to LL400,
which has better shielding, lower loss too, it helped some but,
the Radio Works Isolator really made the difference.

73 K2HAT Lee :)
G0TIY Rating: 5/5 Dec 14, 2008 05:13 Send this review to a friend
Great  Time owned: 0 to 3 months
Just got myself two T-4 line isolators from local
emporium. I had bad RF getting into my equipment
and decided to try them out, i made myself some
patch leads out of 213 coax and placed the as directed on the instruction manual.BINGO no more
stray RF can now run full UK power(400)watts
without any trouble at all.Just make sure that
you make the patch leads correctly there is a
good demonstration of how to make them on you-tube just type in PL295 A guy from TEN -TEC demonstrates how to do them RIGHT. might be helpful to some who are not sure. Great product
a little expensive here in the UK 50 each
but solved my problem.I am almost directly
underneath my antennas so I'm in near field RF makes my situation even worse that others but as i
said my problem as now been eliminated thanks
the T-4 Line Isolators.

G3OZN Rating: 2/5 Jul 16, 2008 12:42 Send this review to a friend
Impaired SWR on Steppir vertical  Time owned: 0 to 3 months
I tried a T4 plus on my Steppir Big vertical and very dissapointing results.
It impaired the SWR on 4 of the bands, I tried it direct on to the EHU of the antenna, also through the DX Eng. coax barrel connector, even at the shack end. All variations impaired the SWR.
Might work with other antennas?
N0YXE Rating: 5/5 Apr 6, 2008 18:50 Send this review to a friend
Great improvement over air choke!  Time owned: 0 to 3 months
I just received my T-4 and immediately unwound my air choke and put the extra coax up against the wall. I added the T-4 directly with an adapter to the feed line of my G5RV ladder line. I haven't fully tested every frequency out, but the auto tuner WILL NOW MATCH (1:1) a big part of the Ten Meter SSB band! My air choke had a six inch diameter of coax with about eight or nine turns on it. 28.330 to 28.500 use to have problems. Now I get a perfect match! Did the unfolding of the extra coax have something to do with this? I also put a T-4 between the amp and the tuner. I'm on the second floor and so far, No Problems!
VA3EP Rating: 5/5 Jun 20, 2006 10:35 Send this review to a friend
T-4-500 line isolator cured mobile RF feedback problem  Time owned: 0 to 3 months
I was having problems with RF feedback in my mobile installation, consisting of a Yaesu FT-857D and an ATAS-120 in a 200 Honda CRV.

I addition to a larger copper wire dressed down the back corner of the vehicle and bonded to the chassis, I had to add some extra ground bonding braid from the antenna mount on the roof rack to a sheet metal screw under the back window lip to get a good autotune with low SWR on all bands.

In spite of the low SWR, I was getting reports of RF feedback in my audio on some bands from some contacts.

When I was in Dayton, I picked up a smaller T-4-500 line isolator from Jim, who suggested it would be best to put it at the antenna end, but that it also might work at the radio end. By the way, Jim is a very friendly and helpful guy!

As it was a lot easier to try adding at the radio end, I patched the line isolator in there, adding a short copper braid from a vehicle chassis ground on the seat mount to the coax connector fastening screw on the end of the line isolator that went to the antenna.

Extensive testing on 10, 15, 20 and 40 meters with a local ham shows that the RF problem seems to have been fixed by adding the line isolator. I am sure a happy camper so far!

You can find more details on my mobile installation (and some general mobile installation tips I discovered) at

Eric Pierce

2E1RDX Rating: 5/5 May 14, 2004 18:07 Send this review to a friend
does a great job  Time owned: 3 to 6 months
I was having a few problems with RF getting into my computer when I was running digi modes all problems solved by putting a T-4G just outside the shack with a 4ft ground stake no more RF getting into the computer just out of interest I tried the earth stake without the T-4G RF present again proving how well the Line Isolator works a little expensive here at 40 but don't hesitate to buy one it solved my problems one happy customer
73 Ian 2E1RDX
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