You can operate the ART-13 without 811's (CW only)
This page on the ART-13 contains information and techniques
dedicated to the ART-13 transmitter. This web page assumes that the reader
has possession of the ART-13 A and B manuals. The Philco "Training
Manual is also a valuable source of info. Perhaps some of my adaptations or mods offend those that want a "perfect" radio. My goal is to modify the radio to suit my needs or rescue a old chassis. Most of my mods are easy to reverse.
My favorite ART-13 is a ugly $5 chassis found under one of the tables at a hamfest -- I saved it and use it for CW.
Basic plan is substitute a low voltage light bulb
in place of the 811 filament.
Figure
5-1 "Typical Operating Voltages . . ."
This
3 tube chain is initially fed with 22 volts.
813-10volts
811- 6 volts 811-6 volts
Click
to Enlarge
The 811 filaments (rated at 6.3V) are in series with the 813 (10V) filament. The ART-13 supply voltage for best operation is 28 volts input to the Dynamotor. The 28VDC output from the Dynamotor chassis will be slightly lower due to internal wiring of the Dynamotor etc.
R121 and 123 (shown above) reduce the 28 volts slightly. Do not remove R121 or R123.
You can't just unplug the 811's as the 813 final amplifier filament is in series.
Operating the ART-13 without the 811's will result in loss of modulation.
Here
is a link to the ART-13 schematic. Trace out the filament wiring. Note
that the 811's are also biased by the filament voltage.
ART-13 Schematic by Mike Hanz KC4TOS
When checking filament voltage go to the pin connections
on each tube socket.
The manuals state that 28 VDC is the "supply"
voltage for input to Dynamotor for all measurements.
The small yellow "Battery" square
represents a voltage range of approximately 5 volts.
Your 28 VDC
target might be some where on that little square. Play with it.
Here is a link to a nice PDF file of the ART-13 with corrections by Mike Hanz. Trace out the meter wiring to see the source of the meter's "Battery" voltage input.
Plenty
of bulbs available. Cheap.
The 1133 bulb is very close to having the proper resistance and wattage.
The 1680 is another choice. Both bulbs are "Close enough for Government Work."
The 1680 and 1133 use a single contact.
Bulbtown is a good source for bulbs and their page is easy to navigate.
The bulbs utilize a BA15 bayonet base. It has a single contact.
The
BA15 Bayonet base is common. Auto stores often stock them as
a license plate
light assembly.
4 pin base removed from a dead 811.
CLICK
to enlarge
Use
your dead tube as a base source. In addition there are plenty of vendors
that stock the 4 pin base.
The large diameter pins are the filament connections.
Q. What about the
811 plate cap leads from the modulation transformer?
A. You need to either
remove or insulate the plate cap leads.
Q. Where are R123
and R121?
A. They are located
right next to the 811 sockets.
Q. Why not use a piece
of resistance wire.
A. I put that in the "Too
Hard to Do Box."
Q. Do I need the
BA15 Bayonet socket?
A. No you can just
solder the bulb.
Q. Are 811's
expensive?
A. They are on ePay.
But go to a hamfest.
Q. CW Only.
Can I also pull the other Audio and MCW chassis?
A. Yes. You
will lose your CW sidetone - but I never use it.
Q. This whole concept
is stupid.
A. Well I like CW,
I had several junk chassis and was short of 811's.
Q Do you have any
other light bulb tricks for the ART-13?
A. See link section
at the end.
Plenty
of room for a BA15 socket inside the tube base.
Be sure and Insulate the 811 Tube Cap lead or disconnect.
Looks
a little strange but takes the place of an 811 in the filament string.
You can test your ART-13
RF output without 811's.
I insulated the leads for testing but later robbed the modulation transformer for another set.
I often just use my low power supply on my CW rig. You only need about 6 and 1/2 amp at 28VDC to run CW and I run 750 volts for plate with this supply. At least you can lift it.
Here
is a link to a keying modification for the ART-13.
Another use of a light bulb in the ART-13
837 Oscillator Filament Network
