1944 National HRO-W Receiver & RAS Speaker Unit

HRO/W Receiver at WB6FZH/KH6

Frequency Coverage-50kc to 30mc, 9 Slide-in Coil Drawers

Power Requirements: 240 vdc @ .07a, 6.2vac @ 3.4 amps

Tubes-2 6K7 rf, 6J7 mix, 6J7 hfo, 2 6K7 if, 6SQ7 det/avc/af1, 6V6 2af & 6J7 bfo

Audio Output- 1.5w @ 8ohms, Headphone Output mutes speaker.

Selectivity- Variable 3.0-.2kc selectivity and phasing @ 456kc

Tropicalized, built for Signal Corps WW2-1944/5

"PW"Precision Micrometer Dial and Tuning Condenser

VTVM "S"Meter Circuit for Carrier Measurements

Separate Power Supply for minimum noise and ac hum

Stable low drift design(Separation of coils and Tube heat)

Used in H.Hughes 1938 "Round the World Flight"

Found in British Admiralty "War Room",and Most US Navy Ships

Antenna Input-Select: longwire, or balanced line

Calibration: Read # on dial, consult chart on coil for frequency

In use @ WB6FZH since 1990 with homebuilt RX-TX AC Power supply

Reference-Photocopies of National Co. Manual, Literature and Articles

I repaired this radio in 1990, and it has been working ever since. It was more difficult to obtain the coils. I am still looking for the 50kc to 100kc and 100 to 430kc coils, but I have the rest.

I often listen to Old radio dramas on the AM Broadcast Band, and can hear KFBK 1530 AM in Sacramento in the evenings for the latest in Northern California news and weather.

I have a TCS WW2 Navy Transmitter (Collins 1943), that is a VFO or crystal controlled, 25wCW or 10wAM 1.5- 12.0 Mc and it is inerfaced with the HRO/W RX to a Homebuilt AC Power Supply. This station can operate on the 160/80/40/30 meter bands. I will keep this Circa WW2 radio station going as long as I can.

The Navy also used the National RAS series of receivers. It was very similar to the HRO/W in design, but had no crystal filter, and was primarily a rackmounted radio system with built-in coil storage, power supply and speaker panel several feet tall. I have been collecting pieces of this system and have one working, but the military nameplates were removed.

I would like to find parts units, coils, speakers, and power supplies for these types of radios to fix some of my sets. Working Sets would be considered too! I would appreciate your help if you hear of any.-Greg

Last Updated: 11/21/97