Rohde and Schwarz EK-07 Page
Yes, I finally got hold of one of these remarkable receivers. This is the Rohde and Schwarz EK-07 D/2. This particular one came from Matt Parkinson. Thanks, Matt! I haven't had it long enough to say a lot about it, but here are my first impressions.  This is the front panel. It has two headphone outputs on the front for a wide-band and a narrow-band (CW) output. No, it doesn't have 1/4" jacks - it has tiny individual jacks for 3 headphone wires (2 are ground). On the back, it has a 600-ohm audio output and a loudspeaker audio output. Of course, these are odd 3-blade connectors that I haven't seen before. |
EK-07 Notes . . .
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For the most part, the front panel controls are pretty much what you would expect. There is RF and AF gains, manual vs automatic gain control, AGC time constant, IF bandspread (6 values from 150 Hz to 6 kHz), BFO, on/off/standby, and noise limiter. |
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The tuning is done in 12 bands. The first 3 are 1 MHz wide, the rest are 3 MHz wide. It operates a bit like the R-390 in that it has a very stable VFO that operates from 3.4 to 6.4 mHz. It is shifted to the desired band by mixing it with the output of a 3 mHz crystal oscillator. That crystal oscillator output is shaped to give it a lot of harmonics, then a filter is switched in to select the correct harmonic for the given band. The R-390 uses a batch of crystals instead. The main tuning looks a lot like an R-388. There is a big, wide readout with a cursor that slides over it. The dial readout is on a drum that turns with the band selector to show just the band you are tuning. The one nice part of this arangement is that it has a vernier that reads out 1-100 kHz. All the tuning mechanism is driven by gears, so there is no slippage possible. |
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This is the signal strength meter. There is also the 300 kHz calibration oscillator switch and the 1-100 kHz vernier. |
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This meter and the switch to the right are dual-purpose. It serves as the audio output meter, but, with the switch, does a diagnostic on each of the 27 stages(!). You have to set it up correctly for each test, but then switching to numbers 1 to 27 will test the selected stage. If that stage is operating properly, the meter will swing to a marked "good" area. What a time-saver! I am not entirely certain, but it looks to me like this tests the basic operation of each vacuum-tube. It does not test, for instance, whether the receiver is in alignment or not. |
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Once you get the case off, this is what it looks like. There is a steel frame that the various units are mounted on. There are tubes visible and changeable from 3 sides of the receiver. I haven't found any on the bottom yet. The units are connected together with coax. |
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The bottom shows the power transformer and some of the bypass capacitors and not much else. ***MORE TO COME*** |
Scanned EK-07 Manuals
As noted before, one of the most difficult parts of dealing with these old receivers is finding the appropriate manuals. Without schematics and other descriptions, it is a hopeless task trying to repair these things. |
| Download 31MB |
"Kurtzwellenempfänger Type EK-07 D/1 und EK-07 D/2" This is the German-language military manual from Helmut Singer Elektronik (see above), dated December 1962. It does have all the schematics and a full technical description. I am starting to translate the manual, but it is pretty slow going. If there are any folks out there that can read technical German and would like to help, please let me know. |
| Download 98MB |
"Reparatur-Handbuch für Kurtzwellenempfänger Type EK-07" This is the repair manual for the EK-07. This one is much more technical than the other one. There are detailed schematics and tables of values. This scan is from Herbert Bloemen. He made a Xerox copy of his manual, and I scanned that. Thanks a million, Herbert! |