Note
QST, Apr 1976, p. 89.
The HT-144B is a low-cost, 2-meter FM hand-held kit manufactured by VHF Engineering of Binghamton, NY. Designed specifically as an affordable, American-made alternative to expensive foreign-built hand-held transceivers and is designed for straightforward home assembly and self-maintenance.
Built primarily on a single pre-drilled G-10 epoxy-glass circuit board with a silk-screened parts layout to simplify component placement. It includes a separate small pre-drilled board for the crystal deck and channel switch.
Housed in a durable, scratch-resistant black textured/wrinkle-finish aluminum case. The chassis is roomy enough to accommodate internal add-ons such as PL tone encoders or a small touch-tone pad on the exterior.
Supports up to 4 crystal-controlled simplex or repeater channels within any 2 MHz segment of the 140–170 MHz band.
The transmitter uses a 4-transistor cascaded audio amplifier driving a varactor diode in the crystal oscillator circuit for true FM modulation. Oscillator uses 18 MHz parallel crystals (20 pF), quadrupling to 72 MHz, doubling to 144 MHz, and driving a 2N5389 output stage.
The receiver uses a 3N204 dual-gate MOSFET RF front end, a 2N5222 first mixer, a 10.7 MHz first IF with a 4-pole monolithic crystal filter (60 dB adjacent channel rejection), a 455 kHz second IF with a ceramic discriminator, and an MFC6070 audio output IC.
Features
– All tunable coils are prewound
– Transceiver is on one G-10 pre-drilled board
– Parts layout silk-screened on boards for easy construction
– Crystal deck is separate pre-drilled board
– Battery-case is AA size accepts alkaline or nicad
– External battery charging/power supply jack furnished
– 1 dual gate mosfet, 2 I.C.'s, 15 transistors, 7 diodes
– Antenna collapsible 17" whip
– Covers any 2 MHz segment between 140 and 170 MHz
– Plenty of room in case for add ons (PL and tone)
Transmitter Specifications
– Output: 2 watts minimum
– 3 dB Bandwidth: 2 MHz typical
– Stability: .002 typical (depends on crystal)
– Spurious Outputs: Down 30db or better
– Modulation: True FM with varactor in crystal circuit
– Netting: Separate trimmers for each channel
– Deviation: Adjustable to 7 KHz
– Audio: Limiter and active low pass filter
– Microphone: Speaker type
– Crystal: 18 MHz parallel at 20 pf
– Multiplication Factor: Frequency times 8
– Current Drain: 500 ma typical
Receiver Specifications
– Sensitivity: Better than .35uV for 20db quieting
– Squelch Threshold: Better than .25uV
– Stability: .002 typical (depends on crystal)
– Adjacent Channel Rejection: 60 db
– Spurious Responses: Down 70db
– First IF: 10.7 MHz
– Second IF: 455 KHz
– Filter: 4 pole monolithic 10.7 MHz crystal
– Discriminator: Pre-tuned ceramic 455 KHz
– Bandwidth: 15 KHz at 3db points
– Crystal: 45 MHz parallel at 20pf
– Crystal Formula: Receive frequency minus 10.7 divided by 3
– Audio Output: 0.5 watts typical
– Current Drain: 10 ma squelched, 100 ma on voice peaks
References
Review. 73, Oct 1974, p. 126.
