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Conar Coletronics Service Inc. Training Kit 3R Transmitter
Conar Coletronics Service Inc.
Modell: Training Kit 3R
Kategorie: Funk und Kommunikation
Gruppe: Transmitter
Beschreibung: 25 Watt CW Transmitter
                                    Circuit Description
Your transmitter uses a high perveance beam tetrode in a
grid-plate power oscillator circuit. Output power for the
three bands is taken from the plate circuit and coupled to
the antenna by a pi-network tank circuit.

A dual-silicon rectifier, full-wave voltage doubler power
supply, furnishes approximately 320V dc for the plate of the
6DQ6B. A combination voltage divider-bleeder resistor
furnishes lower voltage for the screen grid of the tube at
the same time it acts as a fixed load on the power supply to
improve voltage regulation and discharge the filter
capacitors when the transmitter is turned off.

On 80 meters, fundamental frequency crystals (3.7 mc-3.75
me) must be used. On 40 meters, either fundamental crystals
(7.15 mc-7.2 me) or 80-meter crystals (3.575 mc-3.6 me) may
be used. Using 80-meter crystals on 40 meters will produce
less output power than 40-meter crystals because the
oscillator must operate as  a frequency doubler in the plate
circuit, a less efficient manner of operation than operating
at the fundamental frequency.

On 15 meters it is necessary to operate the plate circuit as
a frequency multiplier since fundamental frequency crystals
in the 21.1 mc-21.25 me range are very expensive in addition
to being hard to find. Therefore, crystals in the range of
10.55 me to 10.625 me are recommended for 15-meter
operation. As an alternative, 40-meter crystals in the range
of 7.034 me to 7.083 me may be used. The plate circuit must
be tuned to the third harmonic of the crystal frequency when
40-meter crystals are used for 15-meter operation, a less
desirable method of operation than using crystals in the
10.55 me range, since frequency tripling results in lower
efficiency and less output power. Table 1 summarizes the
crystal selection for the three bands.

To provide stabilization of the crystal frequency and to
protect the crystal from excessive crystal current, a
positive temperature coefficient resistor in the form of a
pilot lamp is used in the crystal circuit This variable
resistance lamp
virtually eliminates any chirp frequency shift of the output
signal when the transmitter is keyed. At the same time it
protects the crystal from excessive currents if the
transmitter should happen to be operated out of resonance
accidentally. The large out-of-resonance crystal currents,
which could fracture the crystal, will burn out the lamp
before they build up to a level sufficient to damage the

A cathode bias resistor is used in the transmitter to limit
the plate current to a safe level as the plate tank is
tuned. If the transmitter did not have this protection, the
plate current would drive the plate current meter off scale
and possibly damage the tube.

The pi-network tank circuit provides a good load match into
unbalanced resistive antenna loads of 50 to 600 ohms
impedance, the most widely used antenna impedances. In
addition, the large output capacitor helps suppress
harmonics from the transmitter. Adequate harmonic
suppression is required by the FCC so that you will not
interfere with other radio services by radiating harmonic

Folgende Anleitungen sind hier verfügbar:

Dokumenttyp: Service- und Bedienungsanleitung Conar-9188-Manual-Page-1-Picture
Seitenanzahl: 20
Dateigröße: 439.96 Kbytes (450524 Bytes)
Sprache: Englisch
Qualität: Gescanntes Dokument, teilweise schwer oder teilweise nicht zu lesen.
Upload Datum:
MD5: 469355eb71b9ff5b30a1b5890abb5c54
Downloads: 26 seit dem 06 August 2017

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