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Q: What is the Stoner PRO-40
SSB?
A: The
BEST SSB CB radio ever made
A number of unusual engineering techniques were
employed in the PRO-40.
To
eliminate crossmodulation interference from adjacent channels, Stoner
avoided the conventional transistor r.f. amplifier/mixer technique used in
virtually ALL CB receivers even today. In fact, no r.f. stage is used at all
and a Schottky diode mixer is employed, similar to that used in commercial
SSB equipment. With no amplifying stages in the front end which could
be overdriven by strong signals, the receiver uses dual cascaded crystal
filters for extraordinary selectivity. Reception of unwanted sideband is
totally suppressed. This allows the radio to be used within 100ft. of
another station without harmful interference. Adjacent channel rejection is
greater than 90dB, and crossmodulation rejection greater than 120dB.
AM heterodyne can be eliminated by the "Whistlestop"
passband audio filter, which can also be used to "peak" audio, helping
separate stations on the same channel. In addition, dual time constant "NB1"
and "NB2" noise blankers are provided.
The PRO-40 employs a
built-in speech processor which creates a unique SSB tailored audio
envelope and "talk power" without distortion or the need for
an amplified microphone. The radio was factory equipped with an Astatic
GD-104.
What does it sound like on
the air? In the 11m environment full of "peaked and tweaked" radios,
overmodulated signals and excessive background, the Stoner shines,
always spurring unsolicited comments on the "sound". "..What kind of radio
are you on?....What kind of mic are you using?...very pleasant
sound...easy to listen to...easy on the ear...broadcast quality...sounds
real smooth...very crisp and clear....." When you key a Stoner,
people listen.
Channel
selection is controlled by a custom "Nitron" chip interfaced with
scan-actuating pushbutton switches. The radio features a true frequency
counter readout active on transmit and receive.
Fine tuning the PRO-40 is a real pleasure with
the wide range 10-turn clarifier and large dial for smooth response.
Another interesting feature is the unique
discriminator type SWR meter, unseen in typical CB radios, indicating the optimum transmitting frequency of the antenna without calibration. The
meter works much the same as the tuning indicator on an FM receiver.
Deviation from the centerline of the meter indicates antenna mistuning and
whether the antenna is high or low of the operating frequency.
Although the PRO-40 does NOT offer an AM or FM
mode, a provision is made to allow interconnecting antenna and power to a
typical external AM/FM CB radio, to allow using both radios on the same
antenna without swapping antenna leads by simply depressing the "AM" button.
This passes the AM/FM signal through the PRO-40 internal multi-stage TVI
filter and frequency counter for accurate display of the external radio
output.
In 1977-80, even
with contenders such as Cobra, Midland and Browning all vying for the high
end CB market with impressive models such as the 2000GTL, 78-999 and Golden
Eagles, the Stoner PRO-40 SSB stood out as the 11m DX Sidebander dream
radio.
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