3-4 MHz ARC-5 WWII Command settransmitter, modified, working, 50 watts output.

This radio will be of more interest topersons intending to operate it rather than to collectors who wantauthenticity, since it is a \"hybrid\". I include ARC-5 inthe description as a generic term, but this radio seems to have someARC-5 components in addition to the BC-676 parts. The chassis paint isrough as you can see from the photos. The chassis appears to havebeen repainted, and certainly the front panel was repainted. Thisradio uses parts from other versions of the command set series. Theserial number and part number on the top cover, BC 475-A, Serialnumber 502. Western Electric are clearly not original to the rest ofthe set. The historical value of this is only as an example of typicalham modifications, rather than the original military configuration.Note that covers were removed for photos and photos show some screwsmissing. These will be replaced before shipping.

This set covers 3-4 MHz. It has beenextensively modified as follows:

1. Output network modified to feed 50ohm loads, keeping the original coils, but with the addition of afixed capacitive load at the output terminal. Output connectorchanged to a UHF type.

2. Filaments rewired for 12 volts AC orDC.

3. Metering jacks added to allowmetering of the tube currents. These have TVI filtering.

4. Cathode keying jack mounted on frontpanel. Also with TVI filtering.

5. RF choke added for plate supply feedto final.

6. TVI filtering added to modifiedpower input plug, now power is fed via external wires.

7. Copper screen used to improve TVIradiation from the chassis.

8. Magic eye tube and crystal aremissing. I believe that if plugged in, the calibration circuitswould work, but have not verified this. Nowadays, calibration isbetter done against a good receiver.

9. The relays used to select thetransmitter are removed. These are not needed for operation.

The modifications have been neatlydone, by a person with good soldering skills. Check inside photosfor details. There may be other modifications in addition to thoselisted, I didn\'t trace all the wiring.

This radio was tested with 195 volts onthe oscillator/final screen and 550 volts on the final plate.

The output power was 50 watts into a 50ohm load, with 140 ma plate current. Loading is smooth and theoutput coupling control was at 3, meaning you can adjust from lowpower to maximum power output without hitting the stop. The antennaloading coil was using a few turns, meaning that reactive loads canbe accommodated at the output. The cathode keying was clean. Calibration was checked at 3.675 MHz and is right on. All of thecontrols turn smoothly.

This transmitter is ready to be put onthe air with the addition of a 12V, 200V and 550V power supply.

The person who did the modificationsapparently used the transmitter for CW operation. For AM, anexternal modulation source would be required for the plate voltage. Ideally the screen should be rewired to also have modulation from theplate supply via a resistor, since the modulation will be better ifboth screen and plate are modulated.

Full money back, lessshipping, if you are not pleased for any reason.

I will double box this with ample bubble wrap, so it should arrive in perfect condition.

sale.