Production Year 1946 at $99.50
The Hallicrafters Skyrider SP-44 Panoramic is designed for operation in conjunction with a receiver to allow the operator a means to visually monitor up to a 200 KHz wide frequency spectrum. The device will allow the operator to visually analyze the characteristics of a transmitted signal such as modulation, distortion, key clicks, carrier shift, parasitic radiations, and other types of transmission parameters. The unit will allow the operator to view both periodic(automobile ignitions, motors, buzzers, etc.) and aperiodic(static crashes) transient disturbances. For the amateur radio operators among us, the SP-44 can also be used to find a clear frequency on a crowded band. A 1/4 phone jack on the back of the unit allows for audible monitoring of all signals within the 200 KHz range at one time. With the SP-44 you will be able to see what you are hearing from the receiver, and be able to monitor and locate stations up to 100 KHz off to either side of your center frequency. The 2 inch CRT(Cathode Ray Tube) display on the panadaptor will show a blip in the form of an inverted V on the screen when a signal is present. The size of this blip is determined by not only the strength of the received signal, but also the transmission type. In other words, a SSB(Single Side Band) signal will be a tad smaller then an AM signal. As the receiver is tuned from a low to a high frequency, the signal deflections will move across the display screen from left to right.
The SP-44 is designed for use with any superheterodyne receiver that employs an IF(Intermediate Frequency) of between 450 and 470 KHz. The unit has been factory set for a receiver having an IF of 455 KHz. If a receiver is used that employs a different IF between 450 and 470 KHz, then the RF bandpass transformers of the panadaptor should be realigned for best performance. In many cases no modifications to the receiver is required. When the SP-44 is connected to a receiver, it will in no way interfere with the normal operation of the receiver.
The SP-44 is supplied with an RF input cable that is used for connecting the unit to a companion receiver. The RF cable terminates in a small loop which is intended to be connected to the plate pin on the converter tube(also known as the mixer or 1st detector) of the receiver. Remember that this connection goes to the B+ line and very bad things will happen if this connection is shorted. At the bottom of this page I list the plate pin number for several popular converter tubes. The RF cable also has an alligator clip that should be connected to the receiver chassis. If the RF cable on your SP-44 has been terminated with say a coaxial terminal, then it probably has been modified some time in the past for a more permanent installation and operation should not be affected. Whether the RF cable is modified or not, when the panadaptor is connected to some receivers with two or more RF stages, it may not be possible to observe up to the rated 200 KHz of bandwidth. However, the bandwidth may be extended by realigning the RF bandpass transformers of the panadaptor so that the peaking frequencies are less then ± 90 KHz from the receiver IF.
The SP-44 has been designed for ease of use, all of the controls that are used to operate the unit on a day to day basis are located across the front panel, while the controls that are used to make trace adjustments are located on the rear apron of the chassis. The electronic components of the SP-44 are mounted on a cadmium plated steel chassis which is housed in a metal cabinet with rubber mounting feet. A light shade protrudes out slightly above the CRT display for greater visibility. It is generally a good idea to have the AVC(Automatic Volume Control) of the receiver turned off when using the panadaptor. Otherwise the signal that appears at the center of the display screen may control the height of all of the other signals that are displayed. For example, if the receiver is tuned to a strong signal, the weaker adjacent signals may be reduced in height or they may not appear at all.
Scanning across the front panel from left to right, the controls and their functions are as follows: at the bottom left hand corner is the Equalizer control that was perfected during WWII and is used to compensate for the varying preselector characteristics of the receiver. In the center is the Scanning Width control that adjusts the bandwidth of the SP-44 from zero to 200 KHz. Next is the Sensitivity control knob that has three functions. The first function of the Sensitivity control is as the On/Off switch, next it is used to control the height of the CRT deflections which at the same time controls the audio output when a listening device is connected to the 1/4 inch phone plug on the rear apron of the unit. At the bottom right hand corner is the Centering control knob which aligns the "pip" of the received signal with the zero mark on the display screen of the panadaptor.
The 10 tubes that are used in the SP-44 along with their functions are as follows: 2AP1 = CRT, 6SG7 = RF Amplifier, 6SA7 = Mixer & Oscillator, 6SG7 = IF Amplifier, 6SQ7 = Detector & Video Amplifier, 6AC7 = Reactor, 6SN7 = Saw Tooth Generator and Amplifier, 6X5 = Low Voltage Rectifier, 6X5 = High Voltage Rectifier, and a VR-105 as the Voltage Regulator. The unit requires a 105 to 125 volt, 50 to 60 cycle AC power source. The normal power consumption of the SP-44 is approximately 55 watts. The physical dimensions of this panadaptor is 11 inches wide by 6 3/16 inches high by 10 3/4 inches deep.
The word Panadaptor is short for Panoramic Adaptor. Technically, panoramic reception is defined as the simultaneous visual reception of a multiplicity of radio signals over a broad band of frequencies. The panadaptor is a really nifty and powerful piece of equipment that can be used for so much more then simply watching a section of the frequency spectrum. Some other uses of the panadaptor include automatic visual monitoring, automatic aural monitoring, three way QSO's or conversations, spotting replies to your CQ call, watching for CQ calls, finding clear frequencies, locating stations whose frequency is unknown, instantaneous signal strength meter, measuring the percentage of AM modulation, spotting distortion on AM signals, spotting spurious and RF parasitics, detecting splatter, detecting carrier shift and frequency drift, finding key clicks on CW signals, checking deviation of FM signals, identifying AM on FM signals, detecting residual hum on a carrier, frequency measuring and setting, quickly checking a band for activity or propagation, and on and on.
Experimental versions of the panadaptor appeared just prior to the outbreak of WWII. Government agencies that relied on standard direction finding techniques for intercept and counter-espionage monitoring quickly learned that it was virtually impossible to follow illegal stations which would change frequencies at random intervals. Panoramic reception solved this problem since they can visually display the signals present on a given portion of the band. Any disappearance and then subsequent reappearance of a suspicious signal on another frequency was immediately detectable. The panadaptor had yet more to offer in the way of direction finding by obtaining null points with greater accuracy which aided in triangulation of the illegal signal. When WWII broke out the panadaptor was pressed into service in great numbers. In the UK there are reports of more then 100 panadaptors at one location operating simultaneously. Panadaptor's were installed at listening posts, control towers, aboard ships and numerous other installations. A spectacular application of the panadaptor was in radar countermeasures. The units would allow the Allied transmitters to match the exact frequency and characteristics of the enemy radar systems for effective jamming techniques. Speaking of radar, the use of pulse automatic gain control, which is used to compress the stronger signals while leaving the weaker signals unaffected, made its appearance in panadaptors long before it was ever incorporated into radar receivers.
Panadaptors have been manufactured by numerous companies through-out the years. The model PCA-2 type T-200 was produced by Panoramic Radio Corporation in New York and is nearly identical to this Hallicrafters SP-44.. The main difference between the two is the finish on the cabinet and the style of knobs on the front. Today, modern companies such as Icom and Yaesu have this feature built into some of their transceivers. If one wanted this feature in a tube era radio then the Central Electronics 100V and 200V some what come to mind. Click HERE for a look at a military style of panadaptor.