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K-20 ; Kolster; USA (ID = 112208) Radio
K-20 ; Kolster; USA (ID = 750298) Radio
K-20 ; Kolster; USA (ID = 750299) Radio
K-20 ; Kolster; USA (ID = 2474487) Radio K-20 ; Kolster; USA (ID = 2474488) Radio
K-20 ; Kolster; USA (ID = 2474490) Radio K-20 ; Kolster; USA (ID = 2474489) Radio
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K-20 ; Kolster; USA (ID = 241565) Radio K-20 ; Kolster; USA (ID = 241564) Radio
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K-20 ; Kolster; USA (ID = 2474487) Radio
Kolster; USA: K-20 [Radio] ID = 2474487 1400x1071
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For model K-20, Kolster; USA:
USA, Kolster; Model K20 - 4
Country:  United States of America (USA)
Manufacturer / Brand:  Kolster; USA
Year: 1928 Category: Broadcast Receiver - or past WW2 Tuner
Valves / Tubes 7: 26 26 26 27 26 71A 80
Main principle TRF without regeneration
Tuned circuits 4 AM circuit(s)
Wave bands Broadcast only (MW).
Power type and voltage Alternating Current supply (AC) / 110 Volt
Loudspeaker - For headphones or amp.
Power out
from Model: K-20 - Kolster; USA
Material Wooden case
Shape Tablemodel, with any shape - general.
Notes One dial (primary tuning control knob)
Price in first year of sale 135.00 $
External source of data Ernst Erb
Source of data Radio Collector`s Guide 1921-1932
Circuit diagram reference Rider's Perpetual, Volume 1 = 1931/1934 (for 1919-1931)
Mentioned in Collector's Guide to Antique Radios 4. Edition
Literature/Schematics (1) Beitman Radio Diagrams, Vol. 01, 1926-1938

All listed radios etc. from Kolster; USA
Here you find 101 models, 46 with images and 67 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.


Forum contributions about this model
Kolster; USA: K-20
Threads: 1 | Posts: 2
Hits: 1768     Replies: 1
kolster-br: ; K-20
Robert Heimbueger

Hi Folks,

I have a Kolster K-20 with a metal casting wheel on the tuning capacitor shaft. It's about 3 inches diameter to receive the dial cord and a tensioning spring. In this case the wheel has some fractures, but is still whole.

I'm wondering if I should apply a sealer or adhesive to this to help stabilize the metal before I attempt to apply the dial cord. Do you have a suggestion for such a material? The fractures are very fine, so a sealer would have to be low viscosity. I also hoped to perform this without dismantling the capacitor shaft. I'm not sure that dismantling is possible, but it would certainly take a lot of time and care.


Thanks for the help,

Bob Heimbueger

Alan Scott Douglas † 16.11.15

Pot metal oxidizes at the grain boundaries in some alloys, and there's not much that can be done about it.  An adhesive might add a little strength, but it would have to be one that cures with no volumetric change, which eliminates anything in a solvent. Some epoxies or cynoacrylates might work, but I've never seen anyone report on using such materials, so you would be experimenting.  It's easier to do nothing.  That also leaves the option to do something in the future, if necessary.

Kolster; USA: K-20
End of forum contributions about this model