General Description
The electronic keyer model ETM-4C contains of an automatic SQUEEZE-keyer and two indep-
endet code stores (2 × 256 bit). Each of the memories can be loaded with up to about 22 letters
of text by simply operating the keyers paddle. Either memory may be recalled independently as
often as desired. For longer messages the two stores can be coupled together thus doubling the
storage capacity.
Once a message is loaded it remains stored until it is erased by loading a new message or by
switching off the power. Model ETM-4C's careful design using C-MOS-ICs reduces the idling
current of the entire set to only a few microamps doing away with the necessity for switching off,
even if the keyer is not to be used for a longer period.
Keyer and store have a common clock running start-stop with the keyer and continuously when
the store is in WRITE or READ mode. Therefore messages edited by the store and texts produ-
ced by keyer operation have necessarily the same speed. It is, however, possible to load the
store at any convenient speed and then to vary the speed of the edited message within the ent-
rie speed range.
The two separate circuit boards for keyer and store are "plugin-type" allowing easy serving. A
faulty circuit board may simply be unpluged and mailed for maintenance. Unplugging the store
board does not affect the function of the keyer.
The keyer output is factory assembled for relay operation (all purpose, 250 V or 0.5 A max.). To
make use of the more economical grid-block keying (max. 300 V NEGATIVE to ground) the jum-
per across pins "R" must be removed and put across pins "G" on the keyer board.
Note: POSITIVE voltages can only be keyed via the relay.
Operating Instruction
Note: Do not switch off the power, if you want to preserve the stored message.
a) Installation
Loosen the two mounting screws on the rear panel and remove the chassis from the case. In-
sert 4 standard size AA batteries (1.5 volts each) into the battery holder. Check polarity signs on
both batteries and holder. The polarity in the holder is marked (+) and (–). Note that the polarity
of tip and case with Mercury cells is different from that of normal batteries. Low battery voltage
will be indicated by dim LED indication during memory operation. Discharged batteries will not
operate the keyer properly. If at any time the keyer appears to be operating abnormally, the bat-
teries should be checked for low voltage. If the keyer is to remain unused for a longer time, it is
recommended to remove the batteries from the holder.
Use shielded cable to connect the keyer with your transmitter. Solder the shield to pin 2 and the
inner conductor to pin 3 of the supplied DIN-connector.
b) Operating the Keyer
The ETM-4C may be operated in the conventional manner by touching either side of the double
paddle for generating dots and dashes. For Iambic operation the double paddle must be squee-
zed to produce a dash-dot or dot-dash sequence according to the lever operated first. The
SQUEEZE-technique enables you to key characters like C, Q, Y, L, F, ar, ka, sk with fewer mo-
tion of the paddle as compared to the conventional manner of keying.
The keying speed can be varied with the speed control from about 8 to 50 words per minute.
To adjust the contacts of the paddle loosen the two mounting screws on the rear panel and re-
move the chassis from the case. The gaps of the silver contacts for dots and dashes can be ad-
justed independently with the milled screws on both sides of the paddle case. A setscrew using
an allen wrench (cf. fig 1) allows the adjustment of the paddle tension.
c) Loading the Stores
Adjust the speed control for a suitable speed.
Set switch "READ/WRITE" to "WRITE" and switch "512/2×256" to "2×256". Press button "PR1"
to choose program 1.
Operate the paddle to key the message into the store.
