Authored by VE3EFJ
3.5 WHAT DISTINGUISHED THE C LINE?
The differences between the B and C line receivers will be discussed in separate detail. Even the C line receivers were different as the years progressed. There is an overall difference between the C line and much of went before, however.
The B line employed copper plated chassis. In the C, this was done away with. The C series also employed dual concentric dial plates where the B series and even the T4X used a single dial plate. The knob skirt on the C line was plain; on the B it was calibrated in kHz and on the TR4 this dial skirt just had radial markings with no numbers.
Generally, in the receivers, Drake made optional on the C a number of things that were standard on the B. The B was a complete receiver out of the box; the C was not. The B automatically switched the AGC as the modes were changed; the C receiver had a 3 position AGC decay time constant setting that was independant of mode. Additionally, the C receiver allowed for more optional band select crystals. The primary reason for the triple conversion on the C was to allow for crystal filter selection and a notch filter. Pundits could argue the necessity of this, but regardless, thats what Drake did.
In the transmitters, Drake switched from a 6HS6 LO premixer to a 6EJ7 on the C line. This is a higher gain tube, but still, the B series did not suffer from a lack of drive. The 12BY7 was used as a driver tube throughout the 4 line. Drake used 6JB6 tubes for the final PA in all of their C and B line transmitters. In the transceivers 3 of these tubes were used to produce 200 watts output. On the separate transmitters, 2 of these tubes were used to produce about 150 watts on 80.
Most of the changes in the C transmitter were for operator convenience. The C series most notably moved the switch for PA current from a separate control on the B to a switch that was activated by pushing the load control in.
The C line also improved upon transceive operation of the separates by providing a separate line for the BFO. This alleviated the requirement to set the receiver and transmitter oscillators exact by the 'canary chirp' method. Additional switch lines were also provided to the dial lamps to indicate the active VFO when slaved together in the C line.
Despite these changes, the B and C series could be slaved together. While the TR7 and TR4 were not transceive compatible with the separate receivers, they still provided for external receive antenna switching and external RX mute. Drake took measures to provide for an intermix of their equipment despite improvements to the gear as the years progressed.
|Table of Contents||Previous Page||Next Page||Drake List Web Site|