Note
The Model 25E was introduced in 1946 by the Kaar Engineering Company of Palo Alto, California. It was designed as part of a one-piece radio-telephone installation marketed primarily to West Coast fishing fleets. It was built to endure hard, demanding, and unforgiving marine environments.
The 25E was often piggy-backed with a transmitter (such as the Kaar 19, 46, or 96 Series) either inside a single cabinet or in separate cabinets. A 19-inch rack-mount version was also offered.
The receiver is considered quite rare today, with historians noting very few surviving units.
It was designed solely for radiotelephone AM use. Notably, it does not feature a Beat Frequency Oscillator (BFO), which is an occasional exception for equipment categorized as a communications receiver.
The receiver features an absolute minimum of controls, consisting of:
– A channelized, crystal-controlled circuit supporting five fixed channels.
– A tunable standard broadcast (BC) band.
– A tunable medium-frequency band (1600–5000 kHz) to cover existing marine frequencies.
Tube Line-up: It utilizes a single-conversion circuit layout with six octal-based tubes:
– 6SK7 – Radio Frequency (RF) amplifier
– 6K8 – Oscillator / Mixer
– 6SK7 – Intermediate Frequency (IF) amplifier
– 6SQ7 – Diode detector, Automatic Volume Control (AVC), and squelch
– 6SQ7 – First audio stage
– 6V6 – Audio output
Power Supplies: The radio utilized a variety of interchangeable, plug-in power packs designed to adapt to a boat's specific power source. These automatically linked to the chassis via an 18-pin Jones plug. A standard 117VAC transformer-operated version used a 5Y3 rectifier tube.
The standard cabinet model includes a central, oval front-facing speaker. On the 19-inch rack panel variant, a dedicated switch was added to toggle audio between the internal speaker and headphones.
Variant Distinction
Kaar 25G: A close relative to this model was the 25G receiver. It shared the exact same basic circuit architecture but differed because it did not include the tunable broadcast and medium-frequency bands.
