Transmitter tube testing
 

I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?

Thanks for you suggestions, Don

I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?
=====================
If the valves are old a Hipot test would be very important to check for
'gassing'.
A Hipot or breakdown test involves a very high voltage up to 10000 V or
higher and a very low current in the few microamperes region.
Real transmitting tubes (used for amateur radio power amplifiers) operate at
anode voltages somewhat higher than 500 V , usually between 2000 and 4000 V.
TV line sweep tubes often used for RF Power amps in the sub kW range usually
need up to 1250 V anode voltage.

In addition to an anode voltage supply ,you need an adjustable up to - 250 V
grid bias supply (a few mAs) . Your 500 V supply will be adequate for a
screen supply when testing tetrodes and penthodes, be it that the max
current would probably not exceed 25 mA.

Frank GM0CSZ / KN6WH

I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?
=====================
If the valves are old a Hipot test would be very important to check for
'gassing'.
A Hipot or breakdown test involves a very high voltage up to 10000 V or
higher and a very low current in the few microamperes region.
Real transmitting tubes (used for amateur radio power amplifiers) operate at
anode voltages somewhat higher than 500 V , usually between 2000 and 4000 V.
TV line sweep tubes often used for RF Power amps in the sub kW range usually
need up to 1250 V anode voltage.

In addition to an anode voltage supply ,you need an adjustable up to - 250 V
grid bias supply (a few mAs) . Your 500 V supply will be adequate for a
screen supply when testing tetrodes and penthodes, be it that the max
current would probably not exceed 25 mA.

Frank GM0CSZ / KN6WH

castles wrote in message ...
I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?

Thanks for you suggestions, Don
++++ I recently built a transmitter tube tester. I made several
sockets ,4 pin 5 pin 6 pin etc for 811, 4-400/3-500, 813, etc.For
instance,to test 811 tubes, I would drop in the 4 pin socket,hook up
proper filament,set bias voltage as per tube data, set up for 811
tubes and test all I had .. I used about 1400 Volts on plate,had
adjustable filament voltage..I had var bias,var screen.. I tested for
emission by reading plate current..I worked out very well for matching
emission on several tubes ..I also applied RF drive ,usually at 14
mhz.using a standard ham transmitter..an old Heathkit is OK..anything
with adjustable RF power out.a soft tube will come up to about normal
and will then start to fall-off..A person could keep on hand a known
good tube for comparsion...good luck Harold W4PQW Ps: I sold my
tester after I finished testing all my tubes..

castles wrote in message ...
I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?

Thanks for you suggestions, Don
++++ I recently built a transmitter tube tester. I made several
sockets ,4 pin 5 pin 6 pin etc for 811, 4-400/3-500, 813, etc.For
instance,to test 811 tubes, I would drop in the 4 pin socket,hook up
proper filament,set bias voltage as per tube data, set up for 811
tubes and test all I had .. I used about 1400 Volts on plate,had
adjustable filament voltage..I had var bias,var screen.. I tested for
emission by reading plate current..I worked out very well for matching
emission on several tubes ..I also applied RF drive ,usually at 14
mhz.using a standard ham transmitter..an old Heathkit is OK..anything
with adjustable RF power out.a soft tube will come up to about normal
and will then start to fall-off..A person could keep on hand a known
good tube for comparsion...good luck Harold W4PQW Ps: I sold my
tester after I finished testing all my tubes..

Hi Harold,

Thanks for the input on the tube testing. I have an HP-6035 Power Supply for the plate source and it
only goes up to 500 Volts. I was hoping to build something that I could just breadboard and then take
apart after I had tested the tubes. So it would be very simple and I would triode connect tubes with
more elements. I thought that this would be better than just selling the tubes with no information on
them. Mainly an emission check. Another response suggested a hi-pot test for gas. Did you find any of
your tubes to be gassy?

Thanks again for your help, Don W6QEY

wrote:

castles wrote in message ...
I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?

Thanks for you suggestions, Don
++++ I recently built a transmitter tube tester. I made several
sockets ,4 pin 5 pin 6 pin etc for 811, 4-400/3-500, 813, etc.For
instance,to test 811 tubes, I would drop in the 4 pin socket,hook up
proper filament,set bias voltage as per tube data, set up for 811
tubes and test all I had .. I used about 1400 Volts on plate,had
adjustable filament voltage..I had var bias,var screen.. I tested for
emission by reading plate current..I worked out very well for matching
emission on several tubes ..I also applied RF drive ,usually at 14
mhz.using a standard ham transmitter..an old Heathkit is OK..anything
with adjustable RF power out.a soft tube will come up to about normal
and will then start to fall-off..A person could keep on hand a known
good tube for comparsion...good luck Harold W4PQW Ps: I sold my
tester after I finished testing all my tubes..

Hi Harold,

Thanks for the input on the tube testing. I have an HP-6035 Power Supply for the plate source and it
only goes up to 500 Volts. I was hoping to build something that I could just breadboard and then take
apart after I had tested the tubes. So it would be very simple and I would triode connect tubes with
more elements. I thought that this would be better than just selling the tubes with no information on
them. Mainly an emission check. Another response suggested a hi-pot test for gas. Did you find any of
your tubes to be gassy?

Thanks again for your help, Don W6QEY

wrote:

castles wrote in message ...
I would like to build a set up for testing transmitting tubes. I was
thinking of just testing a couple of points. My power supply will have a
capability of 500 volts maximum at 2 amps. I would test a triode for
instance for cutoff and then I was thinking of going to the plate
dissapation value. I would do this short term so that the tube would not
need to have forced air cooling.

I am planning to sell some of my transmitting tubes and would like to
advertise them as having passed a series of tests. What tests would be
most meaningful?

Thanks for you suggestions, Don
++++ I recently built a transmitter tube tester. I made several
sockets ,4 pin 5 pin 6 pin etc for 811, 4-400/3-500, 813, etc.For
instance,to test 811 tubes, I would drop in the 4 pin socket,hook up
proper filament,set bias voltage as per tube data, set up for 811
tubes and test all I had .. I used about 1400 Volts on plate,had
adjustable filament voltage..I had var bias,var screen.. I tested for
emission by reading plate current..I worked out very well for matching
emission on several tubes ..I also applied RF drive ,usually at 14
mhz.using a standard ham transmitter..an old Heathkit is OK..anything
with adjustable RF power out.a soft tube will come up to about normal
and will then start to fall-off..A person could keep on hand a known
good tube for comparsion...good luck Harold W4PQW Ps: I sold my
tester after I finished testing all my tubes..