W8QBG - Recent
Projects
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W8QBG Recent Projects II Page
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The
stock Bauer 707, cleaned up a bit from its sojourn in the Palm Springs
desert. The transmitter runs a pair of 4-400's in the PA,
modulated by a pair of 4-400's. |
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Click here for
over-the-air audio from W8QBG on the Bauer 707 describing his
ART-13 mods and other hardware subjects. (Recorded 0730MST,
10-Sep-2006, in Glendale AZ, ~1.5 Meg) |
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Bauer
707 after conversion to HF operation. Added bandswitch (top
center) and output loading control (top left) while retaining existing
plate tuning (top right). Exciter mods described below.
Silver disk between mod and PA tubes is an improved cooling-air
interlock switch. |
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Plate
tank mods for HF added a band switch to select taps on existing tank
coil and a large (2500 pF) variable loading capacitor. |
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Old
BC-band PA tank, a Pi-L network, shown for comparison. |
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Extensive
exciter mods: added tuning adjustments to driver stage, switch for
external driver, crystal socket on front panel and substituted 6146 for
6CA7 for improved drive on 40 meters. |
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Rear-panel
view of exciter/driver mods. External-drive connection is at
left. 25 watts CW from an amateur-radio transceiver will produce
legal-limit power out. |
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Original
exciter/driver stages showing 6CA7 tube. Note lack of access to
crystal sockets and tuning controls. |
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Rear
view of stock Bauer 707. |
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Industrial-strength
fan installed in place of stock unit for additional cooling in Arizona
summers. |
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Bauer
707 "heavy metal". No mods made to power-supply components.
Modulation reactor (center) is a Peter Dahl rebuild. |
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AN/ART-13 |
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ART-13
in Studio 'B' |
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ART-13
Power Supply |
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Homebrew
Grounded-Grid Xmtr RF Deck (2 x QY5-500's) |
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Homebrew
G-G Xmtr Modulator Deck (2 x 810's) |
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Homebrew
4-1000 rig currently at mechanical-layout stage of design flow. |
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Speech
Amp. using "guts" of HP200 audio oscillator |
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Speech
Amp., rear view |
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On to W8QBG Recent Projects II Page