This is a Philips-branded Schoeps CMT 25. The CMT 20 series were Schoeps' first solid-state microphones, with a bridge-type RF circuit and transformerless output. The first few that were ever sold were made near the end of 1963, and the series as a whole (including two subsequent variations, the CMT 200 and CMT 100) continued through 1967.
The CMT 20 microphones were the first phantom-powered condenser microphones on the world market by a few years. The principle of Schoeps' circuit was the subject of a German patent dated February, 1963, and I found and scanned the internal test sheets for when the first microphones were produced, not long after that patent filing was accepted. (The Neumann KM 84, which some people would like to claim was first, wasn't introduced until 1966.)
The CMT 20 series ran on 8.5 Volts delivered through a matched pair of 270-Ohm feed resistors with the positive supply pole grounded, i.e. the reverse of the usual polarity today, and obviously at a lower voltage. The operating current was about 6.5 mA. The sensitivity of the microphone--its output voltage for a given sound level--was more typical of dynamic than condenser microphones. A later variant, the CMT 200 series, was furnished with an additional output stage that made the amplifier's wiring even more crowded, but it raised the signal levels to more typical condenser-microphone levels. The amplifier type CMT 100 was developed for parallel powering, and was also based on the RF-bridge circuit.
It's pretty nightmarish point-to-point wiring, no? I doubt that they were able to make and QC more than one or two of these amplifiers in a day. And the capsules weren't interchangeable, despite being removable; each amplifier was hand-tuned to one particular capsule, and if the user swapped capsules, the microphone often wouldn't put out a signal. The company even put a warning in the catalog that the capsules weren't interchangeable (unlike the company's very successful M 221 B series, which was still being made at this time).
By 1967 low-noise silicon FETs began to be available in production quantities, and at the start of 1968 Schoeps discontinued its RF designs in favor of the new CMT 30, CMT 30p and CMT 40 series, which were distinctly more reliable as well as being simpler to manufacture and maintain. Among those amplifier types, the CMT 30p was the most nearly direct replacement for the CMT 20 or 200, while the CMT 40 replaced the CMT 100; the CMT 30, which used the now-standard form of 12-Volt phantom powering with the negative pole grounded, was new. Finally around 1969 the CMT 50 amplifier for 48-Volt phantom powering was added to complete the series.
--best regards
P.S.: For the cardioid setting, a plexiglass ring was required, as shown in the attached catalog photo; that's why the front end of the capsule housing is indented.
P.P.S.: This capsule type is indeed derived from the M 934 capsules of the M 221 series, but its design and construction are from about ten years later, and it was called the MKT 25. That's more or less an internal name; capsules for this series weren't sold as separate items. -- The mechanical adapter at the bottom of the capsule looks original to me; it exactly matches one that Schoeps has in the display case in their lobby in Karlsruhe, as does the circuitry in your excellent photos.
If this microphone is functional (which would be quite remarkable) do NOT remove the three screws near the pattern selector or attempt to disassemble the capsule any further unless you are prepared to give up that functionality permanently. The amplifier works by means of a dual tuned circuit, one branch of which includes the membrane and backplate as a tuning element. The balance is more delicate than it really should be in a professional product in my opinion; this wasn't a series of microphone that lived up to the expectations for reliability that we think of today, and it is one of the first older series that the company stopped servicing--when they failed, the company would instead offer you a good deal on a later model.
In other words, I would consider it a "collector's item", all the more so if it works. But it's not a microphone to rely on for any actual recording, beyond the possible curiosity value of doing so (which I can fully understand).
P.P.P.S.: If you look at the flat, ring-shaped surface surrounding the spring-loaded contact pin that points from the amplifier toward the capsule, is there a number engraved on it? If so, may I ask what that number is on your amplifier?