[Milsurplus] East German EKB and variants, answers to questions

[Ulrich N Fierz]

G'day all
just received a  message with some questions which might be of wider interest so I post them here:
Q: 1)  On your page 7/9, in the upper photo, on the right-hand side, a switch (I believe) is shown. Can you tell me its designation, and ??  - I do not know yet what it does.
A: On this picture of the power supply the switch (and the fuse) are in the 220VAC input as shown on the left side in the ckt diagram on page 9/9 and serve to turn on the supply, they are accessible from the rear side through a cutout.
Q:  2) the ZS-R5 (EKB) power supply: I wonder if that part will be in the receiver being sent to me! Apparently, 220 v AV @ 50 Hz comes in...2 transformers... and 7.2 v DC/150 mA  and 1.2 v CD/420 mA, respectively...
A: The ZS-R5 is a Czech design and product and I doubt if it's in your Polish version (but don't know). In the East German DV-44/35 there is no mention of an AC power supply, while the use of different external batteries is described therein in detail. There are two transformers because the two supply voltages are floating with respect to ground. Obviously much simpler supplies can be built, e.g. with transformers with two isolated outputs of perhaps 10VAC. When this is rectified and regulated by e.g. an LM317 in each leg (the regulator 1.2V needs a proper heatsink then) you'll get what's needed including short circuit protection. To prevent accidentally blowing up the heaters connect e.g. three 1N4001s in series across this output to limit the max voltage. Also note that the second connector needs two bridges. Do not use switching supplies due to the RF noise these produce. YMMV as always.
Glad to answer more questions if needed and as far as given in DV-44/35...Ulrich  hb9aik - vk2ani
 Ulrich N Fierz
Telecommunication Engineering Services
Zurichbergstrasse 203
CH-8044 Zurich
Switzerland
<hb9aik at yahoo.com>
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