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Reviews For: S.E.M. Transmatch

Category: Antenna Tuners/Matching Networks

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Review Summary For : S.E.M. Transmatch
Reviews: 13MSRP:
Description:
HF Antenna Tuner
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00134.5
G4VVQ Rating: 2020-09-19
Good HF Tuner Time Owned: 0 to 3 months.
Hi Fred in uk, I have just acquired one of these S.E.M Transmatch units, it was of course second hand, made in the Isle of Man, when I got it, it would only tune on 40 and 60 mts, took cover off, found there was a connection broken off the big capacitor, due to loose screws and too much twiddling, soldered it back on the pcb, it was better but still wouldn't tune on 80 mts, then I noticed when I turned the tuning knob right round the capacitor plates were not going right in, so I loosened the grub screw and realigned the capacitor, all works ok now, it will tune balanced, unbalanced and long wire no problem, I use it with a 115 ft doublet, if you use unbalanced antenna or long wire you need to earth one of the balanced terminals, the one nearest the earth post. Drawbacks...mine has no by-pass switch, power is limited to 100 watts from 10 to 80 and 10 watts on 160. Mine has an ezitune function which needs a 12 volt dc supply to phono socket on the back, optional, the schematic seems impossible to get hold of, happy tuning, PS Update, i sold mine some time ago now from Fred g4vvq.
G4WXF Rating: 2018-06-17
Simple Elegant Design Time Owned: more than 12 months.
I bought my first SEM Tran-Z-Match in early 1984 - I still have it and it works as well as it did 38 years ago.
One reason for this is because of the elegantly simple design.
The tuner uses high quality Jackson Bros. Capacitors, smooth vernier reduction drives and a solid case.

The dual section split stator unit is substantially built, using ceramic end plates, silver plated capacitor plates, and is identical to the one in KW E-ZeeMatch and KW 107 antenna tuners (both of which I have owned).
In fact the basic circuitry is the same as the KW units and, as you would expect, performance is very similar (borne out by many A/B tests using dual RF ammeters).

The basic (original) model SEM unit was designed using a similar scheme to the Z-match design, by BY ALLEN W. KING,* W1CJL (which was published in QST May 1955) and had dual HI and Lo Z outputs.

Later versions had a single balanced output with the inks internally connected in parallel.
Options were the Ezi-tune noise bridge module and a switched LOW POWER “Top Band” modification.
Later models also included a “Thru” switch and a dummy load option.

The cost of the units, when production ceased in the late 1980’s, was up around the £300 level - if available today the cost, using similar quality components, would be considerably more.

The following are some observations made using the unit with a variety of doublet and loop antennas - all fed with open wire feeder or ladderline.
.
Apply LOW power initially and alternately adjust the TUNE and COUPLING verniers for minimum reflected power.
Generally the settings on the Tune vernier will be towards the low end of the range with the exception of 3.5 and 14 Mhz. The setting for the Coupling vernier will depend on the Antenna/Feeder configuration.

Failure or difficulty to tune on a particular band is usually indicative of an “oddball” antenna/feeder length. Usually lengthening (or shortening) the feeder will solve the problem.

Suitable Half Top + Feeder lengths for all band (inc WARC) operation are
9.25, 12.85, 27.10 (ssb only) 26.00 (all modes) or 34.10 metres (using a velocity factor of 100 for the feeder). Real world vf’s are below 100.

The power handling capability of the unit is very much dependent on the load. Under normal conditions no flashover should occur when using power levels up to 250 watts.
If flashover does occur this is often indicative of trying to load into a very low impedance.
An example of this would be trying to use a very short dipole on 3.5 or 7 Mhz.
However, I have often used a dipole with a 20M (66’) top very successfully on 80 metres.
.
Only one antenna can be connected to the unit at any time.

For Unbalanced operation, when using an antenna fed via coax, the inner binding post must be connected to the bottom GND post.

For sheer simplicity, longevity and reasonable cost, I haven't found anything better to use at modest power levels with multiband doublet/loop antennas.
MM1EWA Rating: 2015-12-08
Pretty poor Time Owned: more than 12 months.
Sorry to kill the party, but while I'd like to like these tuners they are simply unable to tune anything more than a slight mis-match.
After buying one and it failing to perform as expected on a number of antennas I figured I had lemon and picked up another, sadly its the same.

The tuner fails to perform when put up against KW-107 tuners or even a Leader Lac-895, on various wire antennas, infact the internal tuner of the radio does a better job than these dogs.
The inductor looks very mickey mouse, and the 160 meter 'add-on' inductor takes the biscuit.

The tuner simply lacks the ability to handle any serious mismatch.
As I said, I wanted to like these tuners, but in all honesty save your money and get a KW-107 these SEM things are rubbish I'm sorry to say.

I suspect I'd have better results with these tuners if I ran a couple of hundred meters of waterlogged TV grade coax to my antenna.

Michael - MM1EWA
G4VEC Rating: 2014-10-24
Very Good Quality Components. Time Owned: 0 to 3 months.
Obtained this TranZmatch via eBay about a month ago.Yes, it is a great performer,and appears to be more or less hand assembled,good quality parts as mentioned by most other postings. I have another 'dark horse' ATU also hand assembled, LAR Omni-Match, made in Leeds UK, and as with the SEM, 'production' ceased early 1980's (I think) Back to the SEM TranZmatch, I am puzzled as to why some state that the power handling should be kept to no more than 100 watts, another has stated 50 watts. It seems that no mention is made on the ATU, or instruction sheets as to the max rated power handling. My rig has power output of 100 watts and have loaded this ATU at this power on all bands with no sign of any problems (full size G5RV) The capacitors and coils and all components look as though they could handle considerably more power,my LAR Omni-Match is not as such high quality, but is rated at 200 watts. Of course if one is using a SEM version with a dummy load I doubt if it would be rated at more than 100-watts.....? 73 Mike
M0LSX Rating: 2013-11-21
A great buy Time Owned: more than 12 months.
I wanted one of these & the reality has matched my expectations..It is used at home & on Special Event Stations & will tune almost anything. Even a patch lead & SWR meter on 10 & 20 meters (Don't ask.)
I have had my SEM for at least 10 years now, it has top band & ezi tune fitted, but I do not normally use either.
I have other tuners both manual & auto, including a KW ezi match & a Nevada TM-1000, but nothing has been used as much as the SEM.
The only down side to these ATU's is the fact that they do not handle more than 100 watts...And if buying one, look inside the case, as if they are over loaded they flash over.
The price for these is getting silly, but they are a great ATU..
MI3LVZ Rating: 2009-03-12
Superb! Time Owned: more than 12 months.
My SEM is the basic model but still a great tuner, once you find the resonant point on the band your working, write down your findings for next time and away your go. Will tune a table leg, great job.
M3PMY Rating: 2008-09-25
Super, Lovely, smashing Time Owned: 0 to 3 months.
I managed to buy my Tranzmatch from ebay, it has the 160+80-10 switch, the tuner has no other bells or whistles, but what a performer! it can fool my 897 that a 50ohms match is possible on 80-10m on a 450 ladder line fed 66ft doublet, no meters no mess, just tune her in, write down the tuner and coupling settings for the next time you visit the band of choice, now i can tune it quicker than some auto tuners!!

Get one! if you can.

cheers

Trev
GM0WEZ Rating: 2008-01-19
Quality Manx engineering Time Owned: 6 to 12 months.
If you want a balanced tuner there are not many options - the Johnson Matchbox, the KW Eezeematch, and I think MFJ now offer a balanced tuner. There is also the SEM Tranzmatch, made on the Isle of Man, and widely available on British ebay.

Some of the SEM Tranzmatches have a dummy load, some have 160m coverage, some have the ezitune noise bridge circuit. Mine has all three. The most basic model seems to go for around £60, often more for the options.

It will tune end fed wires etc but it really shines when using balanced feeders to a doublet or loop. Tuning is quick and reproducible. It nearly always copes with 100watts - on a few settings it objects but these can be noted and avoided.

The direct setting bypasses the tuner. This is handy if you're tuning down to medium wave for broadcast stations, navtex, 500khz ham etc, as I find at these very low frequencies you get better results bypassing the tuner.

Ezitune needs 12v at 25mA (centre positive on mine) but isn't really worth having in my view.

Its quite big - bigger than the photos suggest at circa 8.5 x 4.5 inches. There is no integral meter.

The engineering is pretty good with a robust case and fairly well rated components.

The 'manual' (one sheet) is available on line at: http://homepage.ntlworld.com/m.rabel/sem.htm

G6XCJ Rating: 2008-01-19
Excellent tuner! Time Owned: more than 12 months.
Do not exceed 50w. This ATU is magic and yes you dont need the Ezitune(TM) just listen to what ur tuning in, go for the loudest signal. You are set to go. Bought mine in 1980s and it really is worth the 200quid paid for it.
EXG8JCF Rating: 2008-01-19
Excellent:Does the job Time Owned: 0 to 3 months.
Hi, I've just acquired an SEM Tranzmatch ATU on eBay-don't why people sell them, 'cos they seem to be a unique piece of kit ! - anyway, I have the model with the EZiTune feature with an RCA Phono socket on the back marked DC, can anyone tell me what the wiring is for this skt, ie is centre +(positive), I assume 12V DC input ? Also, on the front panel it has a 3 way switch marked Direct, Tuner, Load. I assume that Direct means bypass the ATU ie connect the aerial directly to the output terminals, Tuner means go thru the Tranzmatch, but what does Load mean ? Any help would be very much appreciated. The model has the 160/80-10 switch on the front and only has XMIT and ANT PL259's on the back - I've seen some which also have SO259's for 160, ie 4 SO259.

Once again many thank in advance for any help.

73s

Peter
(ex G8JCF - if you are interested in SDR's then please take a look at http://www.g8jcf.dyndns.org and the G8JCFSDR)

PS. I know this is more of a cry for help than a review, so if I've it got wrong please forgive my newbie ignorance