GROUNDED-GRID AMPLIFIER
TV. SWEEP-TUBE LINEAR
AMPLIFIER
IN THIS AMP I USED A PAIR OF AN OLD TV SWEEP-VALVES (6LF6)
. THEY GAVE ME AROUND 200 TO 250 WATTS OUTPUT ! STILL U
WILL FIND SOME OF THESE TUBES AROUND . LOOK AT THE OLD JUNK AT AN ELECTRONIC
REPAIR WORK-SHOPS . U CAN GET IT OR ALL OF THE TV SET FREE? BELIEVE ME!
THE GROUNDED-GRID DESIGN IS SO POPULAR TO AMATEUR . AND U WILL FIND MANY
AMPS WITH THE SAME DESIGN SKELETON, SO IF U FIND UP ALL THE WOOD
NEEDED TO BUILD UP UR NEST . GIVE IT A TRIAL AND ADD YOUR OWN
CREATIVE BUILDING STYLES .
GOOD LUCK AND
|
|
|
|
VALVES AND BIAS
|
|
RF DECK
THE TWO TUBES AT THE TOP LEFT SIDE . THE RELAY IS AT THE RIGHT SIDE .
THE TANK COIL AT THE MIDDLE MOUNTED HORIZONTAL AT RIGHT ANGLES WITH
CAPACITORS AT THE FRONT PANEL THE CONTROL KNOBS OF THE TUNE AND THE LOAD
CAPACITORS WITH THE SELECTOR SWITCH . YOU CAN SEE THE FAN FIXED AT THE BACK WITH
ITS BODY OUT SIDE THE BOX .I DID THIS AS THEIR WAS NOT ENOUGH SPACE INSIDE
. AND TO AVOID THE PICKING UP OF NOSE THE HOLES OF VENTILATION WINDOW ARE
COVERED BY MESH
|
|
FILAMENTS SUPPLY
|
|
TANK AND OUTPUT RFC
THE NUMBER OF TURNS FOR EACH BAND CAN BE EASY CALCULATED IF U START
TUNING THE AMPLIFIER BAND BY BAND
THE ALL COIL FOR 80 METER
7 TURNS FOR 40
10 FOR 30
13 FOR 20
14 FOR 15
15 FOR 10
ALL THIS ARE APPROXIMATION FIGURES . NOTHING IS SO RIGID LIKE THIS IN
REALITY .
YOU WILL FIGURE OUT WHAT I MEAN WHEN YOU COME
TO WORK WITH COILS AND CAPACITORS TO FILTER OUT OR TO GENERATE A FREQUENCY
WAVE.
|
|
PSU .THE FAN CAN BE A PC PSU'S FAN . CHECK IT'S VOLTAGE BEFORE INSTALL IT
|
|
PICTURE OF THE P.S.U
I USED HERE A BURNED OLD STEP DOWN TRANSFORMER . I REWOUND IT AGAIN
. THIS GAVE ME A 2ND AV OF ABOUT 660V . .ON RIGHT SIDE : U CAN SEE THE OTHER
TRANS USED TO SUPPLY POWER TO THE FILAMENTS AND TO THE RELAY .
LOOK FOR ONE TRANS GIVING U ALL VOLTAGES YOU NEED
(600V+6.3V+12V) THIS WILL HELP TO REDUCE THE TOTAL WEIGHT . HEAT AND
COAST .
|
|
U WILL FIND SOME DIFFICULTY TO GET THE 11V/50W ZENER DIODE SO
THINK ABOUT AN ABOVE SCHEMATIC.
73 DE ST2NH
BACK