I have restored several receivers, but this is my first transmitter.
It seems to be nearly 100% original... paper caps and all. It was
reported to have been regularly used up until last summer by the
previous 30 year owner. I assume that I should go ahead and replace
the paper caps, check the resistors, and check/replace the
electrolytics as I have been for receivers... correct me if I am
wrong. Is there anything else that usually needs to be done/inspected
for a transmitter? I have no way of testing the 4-400 outputs or the
3B28 rectifiers, so do I just fire it up and hope for the best? I
assume I should try and bring this up with a variac, but would really
appreciate a startup procedure recommendation for high power vintage
transmitters.

What a beast. Lifting the power supply will make your eyes water. This
has the largest transformer and tubes I have run across to date. Can't
wait to see what those 4-400s look like lit up.

Dan

On Fri, 9 Jan 2004 16:49:57 UTC, (geojunkie) wrote:

I have restored several receivers, but this is my first transmitter.
It seems to be nearly 100% original... paper caps and all. It was
reported to have been regularly used up until last summer by the
previous 30 year owner. I assume that I should go ahead and replace
the paper caps, check the resistors, and check/replace the
electrolytics as I have been for receivers... correct me if I am
wrong. Is there anything else that usually needs to be done/inspected
for a transmitter? I have no way of testing the 4-400 outputs or the
3B28 rectifiers, so do I just fire it up and hope for the best? I
assume I should try and bring this up with a variac, but would really
appreciate a startup procedure recommendation for high power vintage
transmitters.

What a beast. Lifting the power supply will make your eyes water. This
has the largest transformer and tubes I have run across to date. Can't
wait to see what those 4-400s look like lit up.

Dan

After you replace the caps and bring the voltage up slowly with a
variac, you still shouldn't transmit unless you have a known good,
known low-SWR antenna.

Having an antenna or even better, a Heath cantenna, you can tell if
it is transmitting with a power meter and your receiver. The
receiver will tell you the frequency and a power meter will show you
that the controls are working properly, load, tune, drive, etc.

That much power will quickly warm up a cantenna.

Parasitics are self oscillating finals. If that happens, the plates
of the tubes will glow red when you apply HV but are not talking
into the mike or are key-up. Watch for this and be ready to cut
the power.

Unless you have solid state rectifiers installed, don't waste time bringing
it
up on a variac, especially if it has only been 7 or 8 months since it was
last
used. I would replace any paper caps though. If you have a dc bench
power supply, you can reform the electrolytics in circuit just as a
precautionary
measure.

All the other advice....dummy load, watch for parasitics, etc. was very
good.....
Check the bias voltages on the finals and then watch the plate current when
you
first turn on the HV. The manual should give you the resting plate current.

good luck & 73,
Phil
W5BVB

a dc bench power suppy just to be sure.
No Spam wrote in message
news:ifgU75G3LLdo-pn2-1Z6d7Sr9Ed4V@localhost...
On Fri, 9 Jan 2004 16:49:57 UTC, (geojunkie) wrote:

I have restored several receivers, but this is my first transmitter.
It seems to be nearly 100% original... paper caps and all. It was
reported to have been regularly used up until last summer by the
previous 30 year owner. I assume that I should go ahead and replace
the paper caps, check the resistors, and check/replace the
electrolytics as I have been for receivers... correct me if I am
wrong. Is there anything else that usually needs to be done/inspected
for a transmitter? I have no way of testing the 4-400 outputs or the
3B28 rectifiers, so do I just fire it up and hope for the best? I
assume I should try and bring this up with a variac, but would really
appreciate a startup procedure recommendation for high power vintage
transmitters.

What a beast. Lifting the power supply will make your eyes water. This
has the largest transformer and tubes I have run across to date. Can't
wait to see what those 4-400s look like lit up.

Dan

After you replace the caps and bring the voltage up slowly with a
variac, you still shouldn't transmit unless you have a known good,
known low-SWR antenna.

Having an antenna or even better, a Heath cantenna, you can tell if
it is transmitting with a power meter and your receiver. The
receiver will tell you the frequency and a power meter will show you
that the controls are working properly, load, tune, drive, etc.

That much power will quickly warm up a cantenna.

Parasitics are self oscillating finals. If that happens, the plates
of the tubes will glow red when you apply HV but are not talking
into the mike or are key-up. Watch for this and be ready to cut
the power.

Hi,

wrong. Is there anything else that usually needs to be done/inspected
for a transmitter? I have no way of testing the 4-400 outputs or the
3B28 rectifiers, so do I just fire it up and hope for the best? I
assume I should try and bring this up with a variac, but would really
appreciate a startup procedure recommendation for high power vintage
transmitters.

About bringing the TX up on a variac, IIRC 3B28's are xenon gas
rectifiers and may not strike until the voltage across them is high
enough.


73 de Joe, G3LLV