I managed to get a NIB BC-454-B for pretty cheap. I decided to keep
it 100% original, so I put a Dynamotor on it and cobbled up a 28VDC
supply. Works great as a WWV monitor.

I've never run a dynamotor this long before. The question is: What is
the proper running temperature for these small dynamotors? Seems quite
hot. (Yes, I repacked the bearings).

I have another dynamotor, not for the BC-454, that says "50C continuous
operation" Is that how hot it gets or is that its expected ambient.

TIA.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

Just like any power supply, make sure that the circuit supplied by the
dynamotor is all ok .

Check those paper caps etc.

Is the current on the HV side within spec?

Etc


"Steven Swift" wrote in message
...

I managed to get a NIB BC-454-B for pretty cheap. I decided to keep
it 100% original, so I put a Dynamotor on it and cobbled up a 28VDC
supply. Works great as a WWV monitor.

I've never run a dynamotor this long before. The question is: What is
the proper running temperature for these small dynamotors? Seems quite
hot. (Yes, I repacked the bearings).

I have another dynamotor, not for the BC-454, that says "50C continuous
operation" Is that how hot it gets or is that its expected ambient.

TIA.

Steve.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

(Steven Swift) writes:


I managed to get a NIB BC-454-B for pretty cheap. I decided to keep
it 100% original, so I put a Dynamotor on it and cobbled up a 28VDC
supply. Works great as a WWV monitor.

I've never run a dynamotor this long before. The question is: What is
the proper running temperature for these small dynamotors? Seems quite
hot. (Yes, I repacked the bearings).

I have another dynamotor, not for the BC-454, that says "50C continuous
operation" Is that how hot it gets or is that its expected ambient.

TIA.


I have gotten a couple of emails asking: "have you checked all the
loads, capacitors, etc.?" Yes. The loads are perfect. I am thinking
these beasts must just be hot runners.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

Steven Swift wrote:
(Steven Swift) writes:


I managed to get a NIB BC-454-B for pretty cheap. I decided to keep
it 100% original, so I put a Dynamotor on it and cobbled up a 28VDC
supply. Works great as a WWV monitor.

I've never run a dynamotor this long before. The question is: What is
the proper running temperature for these small dynamotors? Seems quite
hot. (Yes, I repacked the bearings).

I have another dynamotor, not for the BC-454, that says "50C continuous
operation" Is that how hot it gets or is that its expected ambient.

TIA.


I have gotten a couple of emails asking: "have you checked all the
loads, capacitors, etc.?" Yes. The loads are perfect. I am thinking
these beasts must just be hot runners.

They are. Most that are intended to drive a transmitter have an intermittent
duty rating. They are turned on when you key the transmitter, and turned
off when you release.

The units for receivers usually run on the warm side of cozy.

-Chuck Harris

It all depends on the quality of the insulation. Most WW2 stuff used
simple enamel and varnish insulation on the wires-- you probably don't
want to push that much above 50C for very long.

The general rule-of-thumb for old transformers and other things with
windings is: If you can hold your thumb on it for twenty seconds, then
it's okay. Actually, better than okay, the warmth drives out the
moisture which is the number one killer of aged transformers.

Actually the rotor and commutator are what get really hot-- you can
usually tell by smell, if the output air from the dynamotor smells like
varnish, it's too hot-- the varnish is slowly vaporizing, eventually
something is going to short out.

"Ancient_Hacker" writes:

It all depends on the quality of the insulation. Most WW2 stuff used
simple enamel and varnish insulation on the wires-- you probably don't
want to push that much above 50C for very long.

The general rule-of-thumb for old transformers and other things with
windings is: If you can hold your thumb on it for twenty seconds, then
it's okay. Actually, better than okay, the warmth drives out the
moisture which is the number one killer of aged transformers.

Actually the rotor and commutator are what get really hot-- you can
usually tell by smell, if the output air from the dynamotor smells like
varnish, it's too hot-- the varnish is slowly vaporizing, eventually
something is going to short out.

Thanks. That's "thumb time" is my normal calibration, but I never used a
dynamotor before.
--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

"Steven Swift" wrote in message
...

I managed to get a NIB BC-454-B for pretty cheap. I decided to keep
it 100% original, so I put a Dynamotor on it and cobbled up a 28VDC
supply. Works great as a WWV monitor.

I've never run a dynamotor this long before. The question is: What is
the proper running temperature for these small dynamotors? Seems quite
hot. (Yes, I repacked the bearings).

I have another dynamotor, not for the BC-454, that says "50C continuous
operation" Is that how hot it gets or is that its expected ambient.

Steve.

I believe that 50C continuous operation means that is the maximum
temperature for continuous operation. Ambient air temperature (and even
altitude in airborn stuff) as well as circulating air make a world of
difference. Smoking the shellac is not good, and can be smelled easily if
you remove the end dust caps, and leave them off. In the golden days, I
thought something was wrong with dynamotors on surplus so-called Command
Sets if I couldn't leave the palm of my hand on the dynamotor for 10
seconds. Ouch, ouch, ouch........
Old Chief Lynn

"Lynn Coffelt" writes:

I believe that 50C continuous operation means that is the maximum
temperature for continuous operation. Ambient air temperature (and even
altitude in airborn stuff) as well as circulating air make a world of
difference. Smoking the shellac is not good, and can be smelled easily if
you remove the end dust caps, and leave them off. In the golden days, I
thought something was wrong with dynamotors on surplus so-called Command
Sets if I couldn't leave the palm of my hand on the dynamotor for 10
seconds. Ouch, ouch, ouch........
Old Chief Lynn

I found an old manual in my stash that talks about "FITCAL" for
checking out old radios. This TM-11 manual said that the dynamotor is
okay if you could "lay your palm on it for 5 seconds without
discomfort."

Reading that as a spec, my dynamotor is running just fine. There's
no smell of burning.

The radio room in a B-17 must have been buzzing with dynamotors...

Thanks,
Steve.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA

Steven Swift wrote:
"Lynn Coffelt" writes:

I believe that 50C continuous operation means that is the maximum
temperature for continuous operation. Ambient air temperature (and even
altitude in airborn stuff) as well as circulating air make a world of
difference. Smoking the shellac is not good, and can be smelled easily if
you remove the end dust caps, and leave them off. In the golden days, I
thought something was wrong with dynamotors on surplus so-called Command
Sets if I couldn't leave the palm of my hand on the dynamotor for 10
seconds. Ouch, ouch, ouch........
Old Chief Lynn

I found an old manual in my stash that talks about "FITCAL" for
checking out old radios. This TM-11 manual said that the dynamotor is
okay if you could "lay your palm on it for 5 seconds without
discomfort."

Reading that as a spec, my dynamotor is running just fine. There's
no smell of burning.

The radio room in a B-17 must have been buzzing with dynamotors...

I think screaming is more the word. I remember walking alongside of
a B1 at an air show when someone fired up the Auxiliary Power Unit (APU).
Now that was loud. The airplane folks never seem to worry much about
how noisy their planes were inside. They just wore ear protectors.

-Chuck

The radio room in a B-17 must have been buzzing with dynamotors...

Yup, you are right there, but I imagine that with those four Wrights
hammering and shaking out there, with the wind screaming by (and through)
the compartment, the dynamotor noise was difficult to detect!

The B-17's liason BC-375 transmitter had a real whine from it's 1000
volt dynamotor too. Quite a nostalgic synchronized yooping with the
transmitter's keying when running it full tilt. In the middle 1940's, just
after WWII, Keith Martin, W7KGV ran one in his dad's garage. It took about
two, 24 hour days to charge up the old auto batterys collected to run that
dynamotor for a half hours work on 40 meters. Awsome! Those four VT-4Cs were
bright enough to read your copy and fill in the log.
But I digress.......
Old Chief Lynn, W7LTQ