310A - Monophonic FM Tuner
Scott's first FM tuner, introduced in 1954, was the 310A. The 310A had an unusual slide rule dial, where you could actually slide the dial pointer for fast tuning, a tuning knob was also provided for use a vernier. The chassis layout was also somewhat unusual, with the tubes mounted upside down. The 310A FM tuner used a 6BK7 as a cascode RF amplifier, followed by a 6U8 Mixer/Oscillator. The mixer was followed by three 6AU6 IF amplifiers, which drove a 6BN6 Gated Beam limiter tube. The 6BN6 limiter was followed by another 6AU6 to drive the wide band Ratio Detector using germanium diodes. The wide band Ratio Detector had a 2 mHz peak separation. A 12AU7 was used as the audio output stage, while a second 12AU7 was used as a squelch control. The power supply rectifier was also a tube. All the 310 series tuners, through the 4310 and 310E stereo models, used the same RF/IF tube lineup as the original 310A, with the exception that the 6BK7 cascode RF amplifier was changed to a 6BS8/6BQ7 tube. I am not sure at what point this change was made, but the 310A is the only Scott tuner I have seen that used the 6BK7 in the RF amplifier stage. The 310 series tuners, through the 310D, were all monophonic tuners.
310B - Monophonic FM Tuner
The 310B saw the introduction of the traditional Scott round tuning dial, and a conventional chassis layout. While the 310B had the general appearance of later Scott tuners, it was built on a slightly narrower chassis than the typical Scott tuner of later years. The round tuning dial had a small vernier knob mounted coaxially with the main tuning dial.
310C - Monophonic FM Tuner
The famous Scott "Silver Plated" front end was introduced about this time, I am not sure if it was a running change on the 310B, or if it was introduced with the 310C. The front end sub chassis was actually copper plated in the first models that used what eventually became the "Silver Plated" front end. I believe the silver plating was introduced as a running change. The "Silver Plated" front end included the 6BS8/6BQ7 RF amplifier tube and the 6U8 oscillator mixer tube, along with the tuning circuits on a silver plated sub chassis. The small center vernier tuning knob was changed to a larger knob, with a small crank, which became the standard style for the round Scott tuning dial, until the introduction of the stylish fluted plastic knobs with metal caps. The early round dials had the dial scale on a flat piece of plastic, which was screwed to a metal hub. At some point, after the larger crank style vernier was introduced, the flat plastic dial scale with a metal hub was replace by a molded plastic piece that served as both the dial scale and the hub, this change was mad possible by the fact that the larger vernier knob covered the center of the molded plastic dial scale. The molded plastic dial scales, which were used on all the later round dial Scott tuners, had a tendency to crack, if the set screw that fastened them to the tuning capacitor shaft was tightened to tight. Once the dial is cracked, it can no longer be fastened securely to the tuning shaft.
310D - Monophonic FM Tuner
The 310D introduced an improved squelch circuit with a high speed relay for audio muting. The 310D included provisions for connecting a second 310D in a switched diversity arrangement. The chassis was also widened to the same size as the chassis of the 330 series of AM/FM tuners, this became the standard form factor of later Scott tuners.
4310 - FM Multiplex Stereo Tuner
The "Wide-Band 4310 Broadcast Stereo FM Multiplex Tuner" was the first stereo model in the 310 series. The 4310 was intended as a Broadcast monitor, and was built on a large chassis like the Scott receivers. It had a number of special features that set it apart from the other Scott tuners, although the RF Front end, and IF stages were the same as the other tuners in the 310 series. The 4310 included a matching network preceding the tuner front end, which made provisions for connecting either a balanced or an unbalanced antenna, of either 75 Ohms or 300 Ohms, giving 4 possible combinations in all. The 4310 also had VU meters on the front panel, to monitor the audio level on each channel, as well as provision for optional plug in transformers to drive 600 Ohm balanced audio lines. The 4310 was the only Scott tuner to use a DC heater supply for the 6U8 Oscillator Mixer tube, this reduced FM hum. The 4310 also used vacuum diodes in the switching multiplex decoder, in place of the germanium diodes used in all but one other Scott FM tuner, the bottom of the line 370/LT-111. Like the 310D, the 4310 also had provision for Diversity operation, again using relays for the audio switching, this time in stereo.
310E - FM Multiplex Stereo Tuner
The 310E was the last tuner in the 310 series. Unlike the 4310 it was built on a normal size Scott tuner chassis, and was essentially a 310D with FM multiplex stereo added. It included a squelch circuit, and automatic mono/stereo switching, both via relays, although no provision was made for diversity operation. The 310E also had Scott's new styling, which included an extruded aluminum front panel, and new fluted plastic knobs with stylish metal caps.
311 - Monophonic FM Tuner
The 311 series was Scott's second FM tuner design. The 311 was a lower priced version of the 310 model, and was introduced with a round tuning dial, that became a standard feature of Scott tuners for many years. The RF front-end was the same as was used in the 310 series. This front end eventually became the famous Scott "Silver Plated" front-end. After it was introduced, the "Silver Plated" front-end was used in all Scott tube tuners and receivers, with the exception of the 370/LT- 111. The cost of the 311 was lowered by eliminating the 3rd IF stage, and the 6BN6 Gated Beam limiter. The 6AU6 Ratio Detector driver circuit was modified to operate as a limiter. This reduced the IF/limiter chain from 5 tubes, to only 3 6AU6 tubes. This 3 tube IF, became the prototype for all the Scott FM tuners and receivers that followed, other than the 310 series. The 311 also eliminated the squelch circuit, and the second 12AU7 used in the 310.
311B - Monophonic FM Tuner
311C - Monophonic FM Tuner
311D - Monophonic FM Tuner
All the 311 series tuners were built on the narrow chassis, like the early models in the 310 series. The 311 series went through the same technical and cosmetic evolution as the 310 models.
314 - Monophonic FM Tuner
The 314 replaced the 311 series, and made further cost reductions by eliminating the 12AU7 audio amplifier tube. The 6AU6 limiter tube was replaced with a 6U8, the triode section serving as the audio amplifier. The tuning meter used in the earlier Scott tuners was also eliminated, and replaced by a magic eye tube. The 314 was built on the wider chassis used by most other Scott tuners.
LT-10 - Monophonic FM Tuner Kit
The LT-10 monophonic tuner kit was essentially the 314 tuner in kit form, with a tuning meter in place of the tuning eye.
350 - FM Multiplex Stereo Tuner
The 350 was Scott's first FM stereo multiplex tuner. The 350 used the "Silver Plated" front end, and a 3 tube IF like most Scott tuners, but the 6AU6 limiter was replaced by a 6BN6 Gated Beam limiter. The original 350 model was the only Scott tuner to use the 6BN6 in a 3 tube IF lineup. This configuration was never seen again in later Scott tuners or receivers. The innovative Scott FM stereo multiplex decoder circuit was also available separately, as the 335 multiplex adapter, for use in converting older monophonic Scott FM tuners to FM multiplex stereo. The Scott multiplex decoder used a 6BL8 as a composite buffer and 19 kHz amplifier. A 12AU7 was used for the 38 kHz oscillator, driving a germanium diode switching matrix. A second 12AU7 was used as an audio matrix tube to adjust the ratio of L+R and L-R signals, and insure full stereo separation. A 12AT7 was used as the audio output amplifier. The original 350 model had a front panel level control.
LT-110 - FM Multiplex Stereo Tuner Kit
The LT-110 was a kit version of the 350, but differed in that it used the traditional Scott 3 tube IF with a 6AU6 limiter, rather than the 6BN6 Gated Beam limiter used in the original 350 model. The first LT-110 had a front panel level control, like the 350. The early LT-110's had brown painted front panels, which were later replaced by gold panels, similar to factory assembled tuners. The later LT-110's were upgraded to the 350B circuit, and the front panel level control was replaced with a "Sonic Monitor" switch. The vacuum tube rectifier used in the first LT-110, was replaced with a selenium rectifier in the later, revised LT-100. I do not know if this circuit change occurred at the same time as the front panel change. There was no model number change when these changes were made.
350B - FM Multiplex Stereo Tuner
The 350B replaced the original 350. The 350B eliminated the 6BN6 Gated Beam limiter used in the 350, and went back to the 3 tube IF using 6AU6's. The 6X4 vacuum rectifier used in the 350 was also replaced by a selenium rectifier in the 350B. The multiplex circuit remained essentially the same, the major change being the addition of the "Sonic Monitor" feature. The level control was eliminated from the front panel of the 350B, to make room for a switch to control the "Sonic Monitor". The "Sonic Monitor" switch basically detuned the 38 kHZ oscillator, so a beat note with the 19 kHz pilot signal would be heard, if the station was broadcasting in stereo. A mechanical change was made, which moved the 12AT7 audio stage from the multiplex decoder sub chassis, to the main chassis, yielding what some call the 3 tube multiplex circuit, although there was now change in the circuit topology. The gain of the 6BL8 composite amplifier was increased by a change in the value of the cathode resistor, and the Q of the 38 kHz oscillator tank was reduced, both of these changes were to improve the stereo performance. At least 4 different variations of the 3 tube IF were used in the 350B. There was the traditional circuit using 3 6AU6's. Another variation had a 6U8 limiter, like the 314. I am not sure what the triode section was used for, but I suspect it was used to operate the "stereo guide" light that was offered for a while. Most of the "stereo guides" used a 6AV6 tube on a small add on chassis, to control the "stereo guide" light. Most of the Scott "stereo guides" were add on kits that could be added to any early Scott multiplex tuner or receiver, but some 350B's may have had an integrated "stereo guide" circuit. The Sonic Monitor" circuit that was introduced on the 350B eventually replaced the optional "Stereo Guide" light. Another 350B variation used a 6EJ7 as the first IF amplifier, and the 4th variation I know of, used a 6HS6 as the limiter. Both the 6EJ7 and the 6HS6 had more transconductance than the 6AU6's that they replaced, although Scott seemed to always come back to the all 6AU6 lineup.
350C - FM Multiplex Stereo Tuner
The 350C had the new Scott styling, with a silver colored, extruded aluminum front panel, and new fluted plastic knobs with stylish metal caps. I do not know if there were any circuit changes from the 350B to the 350C.
LT-110B - FM Multiplex Stereo Tuner Kit
The LT-110B was the kit version of the 350C, and introduced the new Scott styling to the tuner kits. The new styling included an extruded aluminum front panel, and fluted plastic knobs with stylish metal caps.
350D - FM Multiplex Stereo Tuner
The 350D was the final model in Scott's 350 line, as well as Scott's last tube tuner. In the 350D, a slide rule dial replaced the traditional round Scott dial. The slide rule dial closed the circle with the original Scott 310A tuner, and marked the beginning of the end for quality Scott tuners. The 310A, Scott's first FM tuner, and the 350D, Scott's last tube FM tuner, were the only two Scott FM only tuners to have slide rule dials. The 350D also used a new multiplex decoder circuit, with electronic stereo/mono switching, the first tuner in the 350 line to have this feature. It was also the only separate tube tuner outside the 310 line, that had automatic mono/stereo switching.
370 - FM Multiplex Stereo Tuner
The last Scott FM tuner family to be introduced was the 370 line. This was an attempt at further cost reduction. The Scott "Silver Plated" front-end was replaced by a simpler front-end, based on a 3 section compactron tube. The standard Scott 3 tube IF and Ratio Detector were retained. The multiplex decoder used two compactron tubes. The multiplex switching matrix consisted of 4 vacuum diodes, 2 in each compactron. The 370, Scott's lowest priced tuner, and the 4310, Scott's cost is no object FM tuner, were the only two Scott tuners to use vacuum tube diodes in the multiplex decoder switching matrix.
370B - FM Multiplex Stereo Tuner
The 370B was the 370 with the new Scott styling, including an extruded aluminum front panel, and new fluted plastic knobs with stylish metal caps.
LT-111 - FM Multiplex Stereo Tuner Kit
The LT-111 was a kit version of the 370.
300 - Monophonic AM/FM Tuner
The model 300 was Scott's first AM/FM tuner with a slide rule dial. The 300 and 320 were the only AM/FM tuners Scott built with slide rule dials. The 300 appears to have been the predecessor to the Scott 320 AM/FM tuner, and has a tube complement identical to the early 320 models. The 320 added several features that the 300 does not have. The 300 has only a connection for an AM wire antenna, and does not have an AM rod antenna like the 320. The 300 also lacks the front panel level control, and switching for an external FM multiplex adapter, that the 320 has. Unlike the 330 series of AM/FM tuners, the AM and FM sections of the 300 could not be used independently, to receive the early stereo AM/FM simulcasts.
320 - Monophonic AM/FM Tuner
The 320 was Scott's second, and last AM/FM tuner with a slide rule dial. There are two versions, the first is similar to the model 300 AM/FM tuner, with the addition of an AM rod antenna, in addition to the AM wire antenna connection. The 320 also added a front panel level control, and switching for an external FM multiplex adapter. It is not clear why the 320 was given a new model number, rather than being called a 300 with a letter suffix. The first 320's used a the triode section of a 6U8 as a grounded grid RF amplifier for the FM front end. The grounded grid RF amplifier was followed by the typical Scott 6U8 mixer oscillator circuit, and 3 - 6AU6's in the standard Scott 3 tube IF/limiter circuit. A 12AU7 was used as the audio amplifier, a EM80 was used for the tuning indicator, and a 6X4 served as the B+ rectifier. The pentode section of the first 6U8 served as the AM RF amplifier and was followed by a 6BE6 as the AM converter. The first FM IF amplifier, (6AU6) did double duty as the AM IF amplifier. The grid of the second FM IF amplifier served as the AM detector. Later models of the 320 replaced the 6U8 grounded grid FM RF amplifier with the typical Scott 6BS8 cascode RF amplifier circuit. The AM RF amplifier was replaced by a 6BA6 tube. Two AM bandwidth positions were provided on the selector switch, but these only changed the audio bandwidth, the RF/IF bandwidth was fixed. Unlike the 330 series of AM/FM tuners, the AM and FM sections of the 320 could not be used independently to receive the early stereo AM/FM simulcasts.
330 - Stereo AM/FM Tuner
The 330 was a stereo AM/FM tuner, with two independent round tuning dials. The AM and FM sections could be operated simultaneously, and independently, to receive the early stereo AM/FM simulcasts that many stations experimented with in the days before the present FM Multiplex Stereo system was standardized. I don't know much about the original model 330, and how it differed from the model 330B.
330B - Stereo AM/FM Tuner
The 330B was a stereo AM/FM tuner, with two independent round tuning dials. The AM and FM sections could be operated simultaneously, and independently, to receive the early stereo AM/FM simulcasts that many stations experimented with in the days before the present FM Multiplex Stereo system was standardized. The 330 series of tuners provided switching for three different AM selectivity settings. The three selectivity settings were combinations of two different RF bandwidths, a quad tuned IF filter with two different bandwidth settings, between the 6BE6 converter and the 6AU6 IF amplifier, and two different audio bandwidths. In addition to the two round tuning dials, the front panel included a four position rotary selector switch to select between FM, and AM with any of the three AM bandwidths, for feeding the the main output. The power switch was also a rotary switch. A slide switch was provided to switch the tuning meter between the AM and FM tuner sections. Switching was not provided to switch the 330B for receiving stereo AM/FM simulcasts. To receive these broadcasts, the signals had to be taken from direct outputs from the AM and FM tuner sections, on the rear panel. These outputs were in addition to the tuners main output, and switching between them had to be done in the amplifier. The 330B used the typical Scott FM tube lineup, with a 6BS8 cascode RF amplifier, 6U8 oscillator mixer, and three 6AU6's in the typical Scott 3 tube IF/limiter circuit. The AM tuner used a 6BA6 for the AM RF amplifier, a 6BE6 as the AM converter, a 6AU6 as the AM IF amplifier, and a 6AL5 as the AM detector/AGC. Like all Scott AM tuners, the 330B's AM circuit included a 10 kHz whistle filter. Two 12AU7's were used for audio amplification of the AM and FM signals. A 6X5 rectifier provided the B+ Voltage for the tuner. The Scott "Silver Plated" front end was introduced to the 330 family in the later 330B models, or with the 330C.
330C - Stereo AM/FM Tuner
The 330C was similar to the 330B, but the front panel styling was changed somewhat, and a rod antenna was added for AM, in addition to the connection for an AM wire antenna. The meter switch used in the 330B was changed to a mono/stereo switch, so switching between AM or FM monophonic reception, and reception of stereo AM/FM simulcasts could be accomplished in the tuner. The rectifier tube was changed to a 6X4 miniature tube, from the 6X5 octal rectifier used in the 330B.
330D - Stereo AM/FM Tuner
The 330D was the ultimate development of Scott's stereo AM/FM tuner line, designed to receive stereo AM/FM simulcasts. The switching provisions were much improved over those of the 330C, to provide more flexibility for the reception of AM/FM simulcasts. The slide switch was changed back to the configuration it had on the 330B, to allow switching the tuning meter between the AM and FM tuner sections, without disturbing reception. The power switch was converted to serve as the mono/stereo switch, in addition to switching power. In addition to positions for power off, monophonic operation, and stereophonic operation, it had a fourth position for stereo phase reverse. The phase revere position was useful in receiving stereo AM/FM simulcasts, to correct for reversed phase at one of the transmitters. In the 330D, a 6CN7 was used as the AM detector, replacing the 6AL5 in the 330C. The 6CN7 provided the extra triode section needed to implement the stereo phase reverse function.
331 - Stereo AM/FM Tuner/Preamp
The 331 is essentially a 330 AM/FM tuner, with a monophonic preamp section added. I don't have any information on how the 331 differed from the 331B
331B - Stereo AM/FM Tuner/Preamp
The 331B is essentially a 330B AM/FM tuner with a monophonic preamp section added. The preamp added two 12AX7 tubes to provide the preamp functions. Two magnetic phono inputs were provided, which could be selected by a front panel slide switch. Seven additional positions were added to the four position selector switch of the 330B, bringing the total number of positions to eleven. In addition to positions for FM, and AM with three different bandwidths, as in the 330 series tuners, five different equalization settings were provided for the magnetic phono inputs. Equalization was provided for "EUR 78", "ORIG AES", "RIAA NARTB ORTHO", "ORIG COL.", and "NARTB Tape". The selector switch also provided inputs for Tape and TV. Concentric Bass and Treble tone controls were provided, and a volume/loudness control was added to the power switch. A slide switch was provided to switch the volume control to a loudness control.
331C - Stereo AM/FM Tuner/Preamp
I am unfamiliar with the 331C AM/FM tuner/preamp, and don't have any information on it.
333 - AM/FM Multiplex Stereo Tuner
The 333 was the AM/FM stereo multiplex version of the 330D stereo AM/FM tuner. The 333 retains the two round tuning dials of the 330 series tuners, and while the AM and FM tuner sections can operate independently, front panel switching is not provided to select between the normal FM Stereo Multiplex mode, and the simultaneous AM/FM mode. When the Selector switch is in the "Stereo" position, a chassis mounted slide switch selects either the normal FM Stereo Multiplex mode, or the simultaneous AM/FM mode. This was just one of several concessions needed, to make room for the "three tube" variation on Scott's original ground breaking FM multiplex circuit, in an already crowded chassis. Other changes included simplification of the AM IF stage, to eliminate the IF bandwidth switching and to simplify the IF filter circuit, by eliminating two coils. A slide switch was provided to select between two AM selectivity's, which were provided by switching only the RF and audio bandwidths. The selector switch choose between AM, FM, FM stereo, and FM stereo with sub channel filter in. The tuning meter switch was again eliminated, and the slide switch was used to switch between partial, and full AGC for the FM tuner. A "Sonic Monitor" switch took the place of the rotary power switch, and a slide switch was added for power switching. As a further space saving measure, the 6X4 rectifier tube was replaced by a selenium rectifier for the B+.
333B - AM/FM Multiplex Stereo Tuner
The 333B was the same as the 333, except the styling was updated to include the stylish new silver colored, extruded aluminum front panels, and brown plastic fluted knobs with caps.
355 - AM/FM Multiplex Stereo Tuner/Preamp
The 355 was a large AM/FM Multiplex Tuner Preamp combination designed to be used with the 208 power amplifier. The 355 was the only AM/FM tuner, or receiver, that Scott built which used a single round dial for both AM and FM. The FM tuner and multiplex sections were the typical Scott five tube FM RF/IF design, with the "three tube" variation on Scott's original ground breaking FM multiplex circuit design. The AM section was similar to the model 320 tuner, using a 6BA6 AM RF amplifier, and a 6BE6 AM converter. As in the 320, the AM tuner borrowed the first FM IF amplifier tube (6AU6), for use as the AM IF amplifier. The preamp section of the 355 followed the standard Scott stereo preamp design, but was unusual in that it was the only Scott stereo preamp to use a cathode follower in the line output stage.
399 - Stereo AM/FM Receiver
340 - FM Multiplex Stereo Receiver
340B - FM Multiplex Stereo Receiver
345 - FM Multiplex Stereo Receiver
380 - AM/FM Multiplex Stereo Receiver