Please click your language flag. Bitte Sprachflagge klicken.

T-R Switch 250-39

T-R Switch 250-39; Johnson Company, E.F (ID = 1798192) Amateur-D
T-R Switch 250-39; Johnson Company, E.F (ID = 1798193) Amateur-D
T-R Switch 250-39; Johnson Company, E.F (ID = 1939670) Amateur-D
Use red slider bar for more.
T-R Switch 250-39; Johnson Company, E.F (ID = 1939670) Amateur-D
Johnson Company, E.F: T-R Switch 250-39 [Amateur-D] ID = 1939670 912x928
Select picture or schematic to display from thumbnails on the right and click for download.
For model T-R Switch 250-39, Johnson Company, E.F.; Waseca, MN:
aus ebay, #351608029367, Verkäufer riatla2
Country:  United States of America (USA)
Manufacturer / Brand:  Johnson Company, E.F.; Waseca, MN
Year: 1963 ?? Category: Amateur Equipment (Other, but not Key)
Valves / Tubes 2: 6BL7 6X4
Main principle something special ? Please give information (notes)
Wave bands Short Wave (SW only)
Power type and voltage Alternating Current supply (AC) / 110-120 Volt
Loudspeaker - - No sound reproduction output.
Power out
from Model: T-R Switch 250-39 - Johnson Company, E.F.; Waseca,
Material Metal case
Shape Tablemodel without push buttons, Mantel/Midget/Compact up to 14
Dimensions (WHD) 4.25 x 4.375 x 5.375 inch / 108 x 111 x 137 mm

The E.F. Johnson T-R Switch 250-39 is a compact electronic T-R switch with transmitter pass-through and receiver output, using three SO-239 (UHF) connectors. Power rating 1KW carrier and 4KW PEP. 2-30MHz. Gain 2dB@30MHz, 6dB@3.5MHz. A 6BL7 dual Triode is used as a broadband voltage amplifier followed by Cathode folllower stage which limits output to a separately muted receiver. Instant break-in. Tip jack on panel for monitoring by oscilloscope. It has no external controls.

Editors notes: This product is designed for use with tube type receivers. Use extreme caution when using a solid state receiver because the RF signal at the receive port may be high enough to damage sensitive transistor inputs of receivers. The user should take steps to control this. The TR switch is intended to be used with the receiver on the same frequency as the transmitter. Because this TR switch is left in-line with the transmitter output and any antenna tuner, the tuning circuits in those equipments may reduce the gain at frequencies to which they are not resonated. On the other hand, the TR switch has a high impedance input and works well as a broadband buffer with gain when no additional resonating circuits are connected. The cabinet normally runs very warm.

Net weight (2.2 lb = 1 kg) 4 lb (4 lb 0 oz) / 1.816 kg
Price in first year of sale 29.95 USD

Model page created by Patrick Jankowiak. See "Data change" for further contributors.

All listed radios etc. from Johnson Company, E.F.; Waseca, MN
Here you find 62 models, 52 with images and 27 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.