A 1951 Beginner/Novice Station Introduction In 1951 "The Roy Rogers Show," "I Love Lucy" and "Mr. Wizard" were all new to television. In 1951 General Douglas MacArthur, relieved of his duties by President Truman, bid farewell to Congress. In 1951 20-year-old Willie Mays joined the Giants. Also, in 1951, the Novice license was introduced. This new license was nonrenewable and good for only one year. Novices had limited frequency privileges and only CW privileges on HF. Transmitters had to be crystal control and 75 watts maximum input power. But, by giving the beginner an onthe-air chance to build code speed to 13 WPM, the new Novice license was an effective stepping stone to the General Class license. The July 1951 QST editorial welcomes the new novices and pledges an increasing amount of material more directly useful to the beginner. Articles covering simple transmitters, receivers and basic workshop practices are promised. According to this QST editorial Nothing can compare with the thrill of the first QSO with equipment you have constructed or assembled with your own hands and your primary object in ham radio is communication. At the same time 1951 novice or beginner station projects assumed a tight budget, simple design and required a minimum of tools and special parts to assemble. Ideally most parts could be scavenged from old TVs or table radios. How well did equipment like this perform? Could new novices using this type of equipment really expect much communication? In order to get an idea of the effectiveness of a 1951 novice station I build one and put it on the air. For a transmitter I chose the 6AG7 Novice One Tuber transmitter (May, June 1951 QST). This design was updated in Nov 1953 QST to cover 80 and 40 and stayed in the ARRL handbooks through 1957. The receiver I elected to build is based on the "First Receiver for the Novice" (Aug 1951 QST). Station Description The "First Receiver for the Novice" is a two tube regen. A 6SJ7 regenerative detector is followed by a 6SN7 dual triode providing two stages of audio amplification. It uses home wound coils to cover both 80 and 40 meters. Controls include bandset, electrical/mechanical bandspread, regeneration and volume. With careful tuning SSB and CW signals can be copied but selectivity is lacking and stability is marginal. Like most simple receivers of it s day this one does not support a loud speaker. It is a headphones only set. This is definitely a beginner s receiver. The "Novice One Tuber" is a one tube crystal controlled oscillator with pi-network output. Plug-in coils or a bandswitch are eliminated by using homemade "basket weave" coils and supporting them on three pop sickle sticks. Instead of an expensive tuning meter it uses two small pilot lights. It runs about 10 watts input and puts out 3 to 4 watts on either 80 or 40.
The power supply is fairly straight forward supplying filament voltage, 350 volts for the transmitter and 150 volts for the receiver. All of the parts of this station are mounted on wooden chassis. The slats are spaced properly to allow mounting the tube sockets, transformers and filter capacitor. This works fine as long as shielding is not required. It saved the beginner from buying and using the tools required to bend, cut and hole punch a metal chassis. The wooden slats could even be nailed rather than screwed together to further simplify construction. In keeping with the times I chose to paint the rig in battleship gray like much of the commercial equipment in 1951. Operating All three pieces of my 1951 Novice Station work together pretty well. They each represent about the same level of complexity and sophistication. The one unexpected problem I found was that the receiver is sensitive to the magnetic field generated by the power supply transformer. To avoid hum I have to place the power supply as far away from the receiver as possible. With some frequency and schedule planning I've been able to have several QSOs using this station. All reported a nice sounding signal including a 599 from near Detroit, MI. The 80 and 40 QRP frequencies 3560 and 7040 usually worked best for starting a QSO along with the 80 and 40 meter "novice" bands (3675-3725 and 7100-7150). Using this station did present enough challenge that each QSO felt like a major accomplishment. I imagine the 1951 novice moving beyond the two tube regen receiver fairly quickly. The 10 watt power level of the single 6AG7 is fine for an experienced operator but, again, the new novice would have looked forward to running the 75 watt "novice gallon". Design and Construction details Receiver - Construction A metal front panel is required in order to eliminate frequency shift caused by hand capacity. My front panel is a piece of PC board, the phenolic side hidden by paint. The receiver controls left to right are bandset, bandspread (with smaller pinch drive knob), volume and regeneration. Position the sockets left to right (from the front) coil socket, 6SJ7 socket, 6SN7 socket, so that there is enough room for the bandset and bandspread capacitors. Also important is to allow for CH1, the audio choke in the plate circuit of the 6SJ7. If you are mounting T1, the audio isolation transformer, in the receiver allow for that also. Orient the 6SJ7 socket so that the key points... and the 6SN7 socket so that the key points... I used four
solder strips, two by each of the tube sockets. The parts list calls for straight line frequency tuning capacitors. If straight line capacity capacitors (those with symetrical half circular rotor plates) are used, the high frequency end of the frequency scale will be squeezed. C9, the bandspread series capacitor, sets the bandspread range. It is mounted in the plug-in coil so that the range can be fine tuned for each band. Wire the regeneration control, R2, so that the arm... Wire the volume control, R7, so that the arm is... Many radios of this era connected the headphones directly into the plate circuit of the last audio tube. 100 to 250 volts ran through the headphones clamped to your head. This is a potentially lethal safety problem. T1, the audio isolation transformer, removes this hazard. I have my audio isolation transformer built in a seperate box so that I can move it from radio to radio. While it does not show up in the photos, it is not optional. - Operation Operation requires high impedance headphones, antenna, 150V B+, 6.3 V filament voltage and patience. Start with the bandset and bandspread capacitors set to approximately half capacity, maximum/full clock-wise volume and minimum/full counter-clockwise regeneration. With band coil of choice plugged in and antenna connected, advance the regeneration control until you just start to hear a hiss. This should be a good setting for listening to CW or SSB signals. Adjust the bandset control until you hear stations and then fine tune using the bandspread control. - Calibration Instructions Once you've gotten a feel for tuning a regenerative receiver, you can set the bandspread range and make up a calibration chart. This requires a second, well calibrated receiver. Usually the station transceiver works well for this. When set for CW or SSB, a regenerative detector oscillates, radiating RF on the frequency it is tuned to. The second receiver can be used to tell the frequency the regen detector is tuned to. Decide on a lowest frequency for a bandspread range, set the bandspread capacitor for maximum capacitance and set the second receiver to that frequency. Advance the regeneration control until the hiss is just heard indicating that the regen detector is oscillating. Now tune the bandset capacitor while listening for the regen detector on the second receiver. Once you've found it, note the bandset capacitor setting. Now adjust the second receiver to a new calibration point (for example, 25KHz higher in frequency) and then listen for the regen detector while tuning the bandspread capacitor. Walk up the band noting frequency vs bandspread capacitor settings for each calibration point. If you find that the bandspread capacitor covers to much of the band or that tuning is to fast, decrease the value of C9. Transmitter
- Construction For safety I built my 1951 novice transmitter with a wooden front panel. On the front of the transmitter are the plate tuning (C8) control on the left and antenna loading (C9) control on the right. The key connects to the fanstock clips on the front left while the antenna connects to the fanstock clips on the far right. Coils are wound basket weave style. Build a winding form of seven nails evenly spaced around a 2" diameter circle. Winding in and out around the odd number of nails gives the basket weave. Before removing the coil from the winding form, tie it off using string or twine. Two studs at the right rear provide connection points for the pi-network coil. Position the sockets and coil left to right (from the front) crystal socket, 6AG7 socket, pi-network coil. Insure that there is enough room underneath for the two pinetwork tuning capacitors. Orient the 6AG7 socket so that the key points... I used two terminal solder strips to support the RF chokes and another solder strip for terminating the power cable. - Operation To minimize harmonic output, this transmitter is designed to only operate on the crystal fundamental frequency. 7 MHz crystals are used on 40 meters and 3.5 MHz crystals are used on 80 meters. The pi-network will load into a variety of antenna lengths. Once an antenna is connected, use the standard pinetwork dip-and-load adjustment procedure. Monitor current using either I1 or the lamp/current meter on the power supply. Fine tuning can be done by using the I2 output indicator on top of the pi-network coil. Additional loading capacity, if needed, may be connected across the studs just to the right of the pi-network coil. Power Supply - Construction The power supply supplies filament voltage, 350 volts for the transmitter and regulated 150 volts for the receiver. I1, between the rectifier and the filter, serves both as a current "meter" and as a fuse. If the filter
capacitor fails, shorting to ground, I1 will burn out before any damage is done to the transformer. Choke input improves high voltage regulation but limits the output voltage. If more voltage is required for a transmitter, the filter should be converted to capacitor input. If this is done, the VR tube dropping resistor, R1, needs to be increased in value so that the VR tube is never required to draw more than 40mA. Operating Comments/Notes Keep in mind that I purposely kept this station at the novice/beginner level. Two options to improve the performance of receiver require an additional tube. One would be to add an RF stage with gain control, the other is to add a mixer/converter stage. Similarly I could have added an amplifier stage beyond the one tube oscillator/transmitter. I chose to forgo these complexity increasing options so that I could see how well the beginner solution worked. Receiver selectivity and tendency to overload were the biggest drawbacks to the simple regen receiver design. Unfortunately, tweaking the regeneration for greatest sensitivity also made the receiver most prone to overload. Nearby strong signals or slight drift caused the 6SJ7 detector to go in and out of regeneration. In 1951 the novice operator probably sacrificed a little sensitivity in favor of a stable signal. I imagine a novice struggling to copy the code would not want to be simultaneously fiddling with the receiver controls. In my original station configuration I had an antenna tuner between the TR switch and the antenna. Both the receiver and the transmitter "saw" the antenna tuner as part of the antenna system. I found the regeneration point and frequency varied a lot as I adjusted the antenna tuner for best transmitter loading. I removed the antenna tuner from the station configuration and depended on the transmitter pi-network to load into my 105'inverted L. This step actually made the station more like my 1951 goal and made it easier to use. I had no way to accurately zero beat my transmitter frequency. I finally used my station receiver/code monitor (a 75A3) to listen for the receiver regeneration action. If I heard both the transmitter and the receiver regenerative detector oscillating on the same 75A3 dial setting, I was on frequency. This was probably not a problem in 1951 since all novices were "rock bound". No one expected a response to a CQ to be on their transmit frequency. Everyone tuned the band looking for a call. That habit discontinued with the very stable and accurate transceivers that have been in use for several years. I found the receiver sensitive to the power supply transformer magnetic field. Placing the power supply as far as possible from the receiver cured this problem. Some of today's hams might complain about crystal control. Given the basic receiver of the 50s era, crystal control helped a lot to keep novices legal. A crystal is always on frequency. A drifty VFO tracked by a receiver with minimal frequency readout accuracy in a relatively small slice of the ham band leads to a high risk of one operating out of the band limits. I found crystal control to be a good design balance with the receiver. Conclusion As a beginner station, this receiver and transmitter would have gotten the new novice on the air with a minimum investment. Some contacts may have been made but it would not have been easy. I suspect that many would have become discouraged and dropped out before moving to something better. By the 1956 ARRL Handbook the two tube regen was being presented only as the minimum "shortwave receiver" useful for code practice and for listening to amateur and commercial stations. By then a three tube superhet (converter + regen detector + audio amp) is shown as minimum receiver for the novice. It is also interesting to note that by 1958 the entry novice transmitter shown in the ARRL Handbook was a 3-band 6DQ6 transmitter running 35 watts.