Bringing a RS-6 HF Transceiver back to life

A Spy Radio from the 50s ....COOL! These units were apparently an effort at a miniaturized version of the old reliable RS-1. They never had the widespread appeal of the RS-1 but have a lot of history surrounding them nevertheless as CIA "Spy Radios". Note the absolutely minimal marking and NO "USN", "USAF", etc markings anywhere. The Internet has many sites discussing these radios and their use from emergency bailout radios on SAC B-47s and U-2s to CIA Covert Ops, etc. It would be great to receive some first hand information on these units. There are basically 4 units making up the RS-6 HF Transceiver; the RR-6 3-15Mhz Receiver, the RT-6 3-16.5Mhz Transmitter, the RP-6 Power Supply, and the RA-6 Power Regulator. Each unit is small and light enough to be carried in a large pocket or easily hidden in ?? (the criteria used to be a European loaf of bread ?). There was quite a bit of effort to make these units as small as possible using soldered "pencil" tubes and a well ventilated 2E26 for the PA. Having a slightly different frequency coverage for the receiver and transmitter is not unusual since you RARELY transceive on the same frequency (unless you want to get caught quickly) and the Tx is crystal controlled so "home" knows where you are. Other items include a 100ft roll of antenna wire and two insulators, a single headphone, power cables, assorted power plug pins, an optional key, waterproof carrying bags, and plastic instruction book.

Disclaimer. Before you run off to duplicate the hardware in the pictures (which many of you can do) the RR-6, RT-6, RP-6, and RA-6 are absolutely stock from one end to the other including the sticker (even that oil capacitor I replaced on the RA-6 is original) and all the units have matching serial numbers. The headset is correct for the period but the RS-6 had a single moulded earpiece. The antenna, insulators, ground wire, ground clip, and monitor/antenna wire were made up with period wire, hardware, and pins. The DC power cable is original. The AC cord had crumbled so I cut off the Jones connector and replaced the 2 wire AC cord. The plastic info cards in the RA-6 are original. The optional external CW Key is just that.

RR-6 Receiver

RR-6 Dial and BFO closeup

The RR-6 receiver is a 8 tube superhet, with 455Khz IF, using "pencil" tubes (5899 and 5718) which are soldered in place. Some external connections are quick release pins and seem to work really well. The receiver may be tuned or crystal control. Crystal insertion disables the tuner through a microswitch. The single headphone shown in the picture is an old military unit with headstrap (not original RS-6). A monitor capability is provided from the transmitter to allow listening to your keying via a NE-2 osc. You can adjust the dial per the calibration signal and move the dial marker from side to side. The dial bands and switches are color coded red and blue. The unit comes apart easily and is not too difficult to debug. The only thing found so far on the receiver was one bad capacitor and a fine tuning drive which slipped. Although sensitivity is "good", selectivity on the ham bands is "marginal". This was further complicated by poor friction drive tuning design. I replaced the small (now) hardened rubber drive sleeve on the fine tuning dial with a 3/16" section of new car vacuum hose. Works much better.

RT-6 Transmitter

The RT-6 crystal controlled transmitter uses a 6AG5 Osc and a 2E26 PA. Small NE-2 type neon bulbs are used as tuning indicators and seem to work well. It's packed in there and this unit does not yet have the expected 10W output on the ham bands. The relay looks "a little marginal". The Final tuning is simple and the output network is designed for loads of 75 ohms to 1200 ohms. It will load up most anything ...hand rails, flag poles, porch railings, stairways, etc. It will even load into the 100 ft spool of wire which comes with the unit.

Fold out CW Key

The transmitter has a small self contained CW key. When the small key is folded into the unit the contacts are closed. An external CW key or code tape reader may be used by plugging into the jack (the small CW key must be out).

Power Supply and Regulator

RP-6 Power supply

The RP-6 power supply will work off 6VDC or 70-270VAC from 40-400Hz. An assortment of plug pins is provided for literally any combination. Beware that the AC power plug has a "HOT" male end if left plugged into the wall AC outlet. The original RS-6 came with a blank cap to prevent accidental shock but don't trust that and unplug from the wall AC outlet FIRST. A switch on the power supply is stepped from "OFF", through the voltage ranges, until the NE-2 neon bulb comes on, indicating you are at the correct voltage level. DO NOT GO PAST THIS POINT ....the resultant B+ outputs will be much too high. The power supply also contains a 6X4 rectifier tube and a 6VDC vibrator. The lid on the power supply flips up for servicing the two fuses. All the connectors are well marked.

RA-6 Regulator

The RA-6 regulator contains the Tx/Rx switch, two 5744 "pencil tube" 90V regulators, and power filtering capacitors/chokes. This is where I encountered a defective 1.5mfd oil filter capacitor. It was hot, swollen, and dangereous (could have ruptured hot oil). The output of the regulator is 420VDC for the transmitter and regulated 90VDC for the receiver. The transmitter Osc section has power during receive. The RA-6 has a flip up lid which houses plastic cards with interconnect instructions and schematics, the headset, spare fuses, and some power cords.

I've read that these units are difficult to use due to all the wiring but found the connections to be very straight forward and easy to use. But then, I don't have "the enemy" breathing down my neck. Found an OD green WWII backpack of some sort (12" x 12" x 4") ....fits nicely.