by F1FRV

Rev6 March 2007, mods: Schematic of adaptation for SDR-1000

Rev7 March 2010, mods: Updated control box layout on PCB and values schematic page 4

Rev7b april 2014, mods: Updated amp & control box schematics.

Socket for GS-35b adaptation

For the fun, click on rotating "red tools"

This cold war era equipmentis a semi automatic (10 memories) 1,5 to 30 MHz linear amplifier. R-140 stations have been used in all Warsaw pact countries, with front panel in each local language. Original design uses a driver stage with 2 x 6E5P small tetrodes for about 100-200 mW input only. Final stage use a 1 kW dissipation glass/metal tetrode GU-43b or Q-1P/41, or a ceramic/metal Q-1P/42.

To use it in amateur radio station, with a 100 Watts class transceiver, we removed the driver stage, and made a wide band 50 to 200 W input adaptation, It was also necessary to add blower, antenna relays, covers, logic & safety circuits, and power supplies. With good power supplies, and PI network modifications, in amateur radio service, 1.6 kW RF SSB output can be safely reached. With a GU-78b, power up to 5 kW can be obtained. It is also possible to replace the tube by a GS-35b triode, to simplify power supplies and safeties, and have more output power.

Some improvements on output PI network to have a better match in ham bands can be done, see later-on.

Nota: SDR-1000 low power users will maintain the driver working.

This is the "rebuilt" schematic diagram (updated)


Download non inductive resistors data


6M1 FRONT PANEL OPEN (very nice mechanical & cabling works)

Click here for other pics


Download all output measurements: 6M1 measurements.zip


The remote command box for this amplifier


You can see some pictures (click to enlarge)

Connectors 6W1 & 6W2 decoupling, remote control box front and rear

Rear connectors to supplies & control box

Output relay for 2 kW max, input relay S2, with 6 dB attenuator

Output relay for 5 kW max with DIN 7x16 connectors

Wideband input circuit, wires shielding added behind connectors 6W1 & 2

Measurements: SWR at amplifier input, SWR in by-pass, relay insulation

Download schematic diagrams (rebuild & originals) and PCB's here:

 R-140 amp and control box: schematics & PCB

Internal link to output pi network improvements

Internal link to tetrode power supplies & auxiliary circuits

Internal link to high voltage power supply

Internal link to replacement of GU-43b by GU-78b to increase power

Internal link to "7PSZ" R-140 antenna tuner

Radio Scanner.Ru

(english translation)

Links to other

R-140 pages


(english translation)

Special thanks to some hams, who helped me to find technical documentations:
Pavel Vachal OK1DX, Milan Rusky OK1MR, Ludek Odehnal OK2ZC, and www.cqham.ru.

Nota. Some other original R-140 schematics and documents are available. In case of need, go to R-140 main page.

Dominique - f1frv@sfr.fr OR

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