The E.F. Johnson (model 250-30) Kilowatt Matchbox was and is famous for its ability to match practically any antenna (Google the online reviews). Calling it a Kilowatt was a just a moniker, the components are rated for duty at least twice that. Many matchbox owners modified their units; multiple ideas and examples are easily found online. Unmodified matchboxes are now rare. Many amateurs construct their own antenna tuners, some with open frame construction, others with an enclosure.
Here are excellent condition parts which were taken from a Kilowatt Matchbox. All components have been cleaned and electrically checked out. This is an great way to buy the major components to construct your dream high power tuner.
The components (refer to E.F. Johnson schematic, see photo 20):
C1 (photos 16, 17, 18) is a part # 152-517-3 dual section variable capacitor (manual parts list specifies 152-517-2). Marked 110 uuf, 7000 volt rating, air gap .175. Very clean. With the sections connected in parallel, I measure 43-225 pf. Prior owner made two custom Bakelite (or similar) insulated mounting bars, which are easily removable if unneeded. Mounting brackets included. 5.5 x 5.5 x 9". Will be double boxed in the shipment.
C2 (photos 5, 6, 7, 8) is a part # 169-32 four section variable with two rotors (manual parts list specifies 160-32). I measure 19-102 pf for each of the four sections. Very clean. Mounting brackets and 4 porcelain mounting pillars included. Capacitance is maximized in two sections when minimized in the other two. Shafts of the two sections are connected with a non-conductive arc-resistant porcelain connector. 5.5 x 6.5 x 9". Will be double boxed in the shipment.
L1 (photos 9, 10, 11) inductor is a part # 232-511 dual edgewise-wound Hi-Q inductor (manual parts list specifies 236-511-1). Catalog says coil construction is plated (probably silver) copper strip with 3 mycatex insulator bars. Main inductor 3.75" diameter; outer coupling inductor 5" diameter. Coupling inductor has one attached end connector strip, main inductor has three such strips at each end plus 7 attached band tap strips. I measure 27 uH for the main coil and 5 uH for the coupling coil. Includes four 3" aluminum mounting pillars and hardware. In the original design, the pillars lifted the inductor above the (not included) dual section 5 position rotary switch. Additional or different tap attachment points can be done simply by soldering to the plated coil. Will be double boxed in the shipment.
Four original Kilowatt Matchbox rubber mounting feet (photo 21), 3 x 3.5 x 1.5 cm, with mounting hardware.
Two 3" (skirt diameter) Bakelite (or similar) knurled control knobs with 4" diameter 180 degree tuning scales marked 0-100 (photo 20). One knob is fixed (but easily user-removable) to the tuning scale. The other knob turns a 4:1 ratio Velvet Vernier (photo 22) with attached index mark. Smooth action of vernier, lubricated. All very good condition, tuning scales unscratched.
Two shaft couplings for 1/4" shafts, one brass, the other probably steel (photo 19). All setscrews included.
Two paired porcelain lead-in bushings, each 3" long x 1.25" diameter with all hardware (photo 4).
One 2" diameter porcelain non-arcing insulated shaft coupling for 1/4" shafts, similar to the coupling found between the sections of C2 (photo 3).
Two paired General Electric single circuit six-position high voltage rotary switches (photos 1, 14, 15); these have been cleaned, lubricated, and tested. Provided with original pointer knobs, eight after-market 2.25" brass mounting spacers, and eight 3" mounting bolts. Very heavy duty. One source says this type of switch was originally provided with the WWII BC-375 and BC-191 aircraft transmitters (used together, these could be potentially used to replace the original Johnson dual circuit five-position rotary switch; however, suitable five position ceramic dual circuit rotary switches are also presently available inexpensively from more than one source on eBay). Originally intended to be panel mounted without the spacers. Will be double boxed in the shipment.
RY is part number 22.1153 relay with 5000 ohm DC coil (photos 12, 13). Mfr. by Remco Inc., Mankato, MN. DPDT contacts plus an additional single normally closed contact. Heavy duty contacts and porcelain base. Provided with mounting hardware and 8 thumb-screw binding posts with solder lugs. Tested and working well with 90-150 VDC applied to the coil. By comparison of online photos, this appears to be the original type relay supplied with the Kilowatt Matchbox. Will be double boxed in the shipment.
Additionally, the Kilowatt Matchbox schematic and Operation Instruction Manual (printer copy; see photos 23, 24), the original 7-lug Bakelite (or similar) feed through connector strip from the Matchbox rear panel, and six cleaned SO-239 coaxial connectors, mounting hardware, and several lengths of heavy gauge bare connecting wire will be included. These last pieces are not shown in the photos.
A real find for someone interested in higher power antenna tuner design and construction.