[TenTec] OT: S.E.M. TRANZMATCH (matchbox)

[Rick - NJ0IP / DJ0IP]

Sri guys, I posted wrong data on an earlier post.

The matchbox was indeed for high power, not 100w as I stated.

Even though Jerry (with a J) got older today, it’s my grey cells that are failing!

 

I believe it was Tom who asked about the SEM matchbox.

Tonight after work, I dug through my archives and found the information Paul advertised with.

 

Below you will find, word for word, the text of the catalog.

I don’t have the year of the catalog, but I do have a letter from Paul, dated November 1994, so it was in this timeframe.

 

At that time I was negotiating a deal for Paul with a US Ham Radio company to become his US distributor.

That company was bought out by another in Texas; Paul’s health went south, and the deal never materialized.

Thus Paul’s interesting and innovative products never made it (commercially) to the US.

 

Here we go:

 

-S.E.M. TRANZMATCH Mk III AERIAL TUNING UNIT

TECHNICAL DATA:-

Matching Range:  15 – 5000 ohms.  BALANCED or UNBALANCED.  

Frequency Range:  1.8 – 30 MHz.

Power:  1,000 Watts max.  

Construction:  Steel case, anodized aluminium front panel, black cover.

Size:  8¾” x 4” front panel.

Weight:  4.5 lbs.

Rear Connectors:  SO239 to transmitter receiver.  SO239 to co-axfed aerials.  2 screw terminals for wire feeders, either end fed or balanced twin feeders of any impedance.  Screw earth terminal.

Front Panel Controls:  TUNE and COUPLING slow motion calibrated dials  BAND SWITCH 80-10 metres continuous OR 160 metres.

FUNCTION SWITCH:  DIRECT, TUNER, DUMMY LOAD, EZITUNE ON/OF (Optional)

Without doubt this matching unit provides wider matching range and VERSATILITY than any other range.

It will match the aerial to 50 ohms, either balanced and fed with twin wire feeders low or high impedance.  OR unbalanced, either co-ax cable or end fed aerials.

The termination to the aerial is by air coupled coils to provide a balanced output so there is no direct connection between the aerial and the radio, this can be a great help with TVI and RFI breaktrough on both transmit and receive.

The circuit is a BANDPASS type, giving attenuation on either side of your frequency, reducing harmonics and other spurii.  Other ATUs often give no selectivity.

A switch selects either STRAIGHT THROUGH to the aerial, or via the TRANZMATCH or to the optional 50 ohm 100w DUMMY LOAD.

You can use the conventional method of an SWR meter to adjust your TRANZMATCH, but we advise that you have the EZITUNE built in.  This circuit was invented by S.E.M. to overcome the difficulties of watching an SWR meter, with the meters swinging wildly and the transmitter power output changing with the varying impedance.  It stops the annoying tuning signals on the bands, and think of the lack of strain on your transmitter by tuning up the receive.

So useful has this development been that over 90% of the TRANZMATCHES we sell have the EZITUNE built in.  (For further details see below)

Prices:  TRANZMATCH  ₤179.00;  EZITUNE built in ₤59.50 Extra.  DUMMY LOAD built in ₤10.90 Extra.  All including VAT and delivery.

An indication of the robust construction of these units can be seen from the ones that have been in daily use for 20 years.

 

 

The EZITUNE was a noise generator, generating random noise across a wide spectrum.

You turn it on, tune the matchbox for maximum S-Meter reading on your receiver.

Paul designed this nearly 40 years ago.

 

73

Rick