4A
This Transmitter was introduced to the amateur radio community in the October 1933 issue of QST. It is a crystal-controlled CW-only transmitter capable of 20 watts RF output. The crystal and associated band-changing coils were plugged from the top of the unit. However, the production units were a bit different than the Museum's artifact. The Power Amplifier Neutralization control was moved to the front panel as well as the crystal module. Notice this particular unit did not have a manufacturer’s plate - that we can see.
Construction
The 4A was a kit, all parts included, however, you were responsible to purchase the tubes separately. Like many home-assembled projects of the day - this unit had no top cover, sides or back.
As Advertised
The 4A transmitter marks the entry of the COLLINS line in the extremely low-priced field. The 4A uses a 47 crystal oscillator and parallel 46's in the power amplifier permitting an output of 18 to 20 watts on 1.7, 3.5 or 7 me. The power amplifier is operated on the crystal frequency in each case. Despite its low cost, the 4A embodies the mechanical and electrical refinements found in the larger COLLINS transmitters. A separate power supply is used for the oscillator to reduce frequency "chirp." Standard COLLINS plug-in coils are employed. A single Weston meter is provided with a switching arrangement to read plate and grid currents. The 4A is ideal for an amateur who wants to start out with a minimum investment and yet have a transmitter which will deliver a high quality C. W. signal. The 4A can also serve as a stand-by transmitter in a high-powered station to be used when full power is not required. Really surprising results can be obtained and amateurs who are accustomed to think in terms of kilowatts can get a great deal of service and amusement from one of these little transmitters.
