HISTORY:
Ex a lovely T2 LUXMAN AM/FM Tuner which has become an "organ donor" due to a damaged casing.
I don't see these around very much nowadays, very useful for those who still partake in the art of radio equipment "home brewing" - no longer is this variable capacitor suitable for use in another LUXMAN T2 as I have completely stripped the inner PCB out so that the future use of this component has more possibilities.
VARIABLE CAPACITOR - Mechanical
Manufacturer is unmarked on the component and unknown
Circa late 70's - early 80's
Most likely to be of Japanese origin
Marked on one end as:
5 electrically separate gangs, although one "side" of the capacitor is electrically common to all (the rotating shaft section)
COMPONENT DIMENSIONS:
MAIN BODY - 79mm depth x 72mm wide x 30mm height
The capacitor(s) only take up less than half of the available "real estate", being just 35mm wide
The remaining empty area(s) used to house the input tuned circuits, preamplifier FET etc - I have completely removed those boards so this empty space is a nice area for the custom fitting of your own RF input circuits, surrounded by a strong RF shield (no top cover though)
All walls of the variable capacitor block are 2mm thick metal and most joins are heavily soldered - this is one very strong framework for the capacitors.
All capacitors use a common Brass shaft which is connected to a gear mechanism and 1/4" round shaft. These gears mean that you need to add a further 9mm height and 32mm to the depth of the main body measurements above.
Three main "tags" underneath act as anchor points when secured to a PCB plus there are other tags to access one side of each variable capacitor available for PCB insertion.
Weight is 200g for the complete assembly
COSMETIC CONDITION:
USED
Clean (particularly between vanes!)
Absolutely NO corrosion points at all
Shaft rotates smoothly and without "backlash"
Gears used are ALL METAL and there is no teeth damage
Shaft fitted to the gears is 15.45mm length x 5.9mm diameter
ALL connection points have had previous wiring removed and there are no substantial solder "dags"
TESTING:
First, the mechanical side of things. The gears mean that the capacitors rotate from fully open to fully closed with the shaft being rotated through 540 degrees (1.5 full turns)
Of course all capacitor vanes move in unison, being on a common shaft, can't be sure but this shaft looks to have ball bearings.
Electrically checked EACH variable capacitor for shorts or other signs of vane damage by rotating through from fully open to fully closed - no problems at all with any vane.
I then measured the "fully closed" capacitance of each gang
Gang 1: 85pF
Gang 2: 320pF
Gang 3: 20pF
Gang 4: 320pF
Gang 5: 20pF
Rotated through to the fully open position and all capacitors are now "open circuit" i.e no measurable capacitance
Nice little, very well made antiquity from the days of analog radio receivers although there is no reason they could not be use on low power (QRP) transmitters with a variable frequency range e.g Amateur Radio use perhaps on HF
Now that my description is complete, this component has been laid on a strong protective bed, bubble-wrapped to protect the vanes and then sealed within clear plastic
