Le 15/07/2010 20:48, Antonio Vernucci a écrit :
Mine has the same behavior, and the technical manual says that it's
the way it works so no problem.

Furthermore it seems rather logical as in A.M. mode the H.T.s are only
required when the mike paddle is depressed... The dynamotor speed
settle time is acceptable in this mode but try to figure out the
dynamotor being turned on and off at the keying speed in CW!

Hope this helps,


Thierry
--

Thanks for information. OK for CW, though for AM it gives me a strange
feeling to hear the dynamotor starting every time I push the microphone
PTT. In the BC-191 / BC 375 the dynamotor instead runs continuously,
either CW or AM.

I have built an AC power supply for my ART-13 and I must now adapt its
control logic to that of the ART-13, which is not immediate to
understand because the schematic diagram is not easy to read (so many
relays ...) and the service manual describes things using a rather odd
sentence structure, difficult to follow. I do not succeed to get the
antenna relay energized in any way, so I fear I'll have quite a hard
time in the near future to have it in working order.

73

Tony I0JX
Rome, Italy

You're welcome, it's always a pleasure to have an opportunity to read or
to talk about this wonder.

About the behaviour of the dynamotors on the wwii US transmitters I can
add that on the BC604-684 it also goes on and off depending of the ptt
or tune button.

I must say that I've not powered up my T-13 for a while, about 22
years... A true shame. I've got all the components including a very
strong 19" rack to build an AC P.S. in storage, waiting for the right
day to come as the dynamotor seems to be a little too much an outdated
item by today's comfort, noise and energy savings standards.

In fact I'm still hoping to have enough spare time someday to get a
license to use this Tx. as it should be, not only to power up a dummy load.

I'll have a look in my documentation as I believe I could have some
schematics showing the connections required on/between plugs to operate
the Collins with a separate mains supply.

Also, I would be glad to know if you've got any help from ICP for your
RF ammeter?


73,

Thierry



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You're welcome, it's always a pleasure to have an opportunity to read or to
talk about this wonder.

About the behaviour of the dynamotors on the wwii US transmitters I can add
that on the BC604-684 it also goes on and off depending of the ptt or tune
button.

I must say that I've not powered up my T-13 for a while, about 22 years... A
true shame. I've got all the components including a very strong 19" rack to
build an AC P.S. in storage, waiting for the right day to come as the
dynamotor seems to be a little too much an outdated item by today's comfort,
noise and energy savings standards.

In fact I'm still hoping to have enough spare time someday to get a license to
use this Tx. as it should be, not only to power up a dummy load.

I'll have a look in my documentation as I believe I could have some schematics
showing the connections required on/between plugs to operate the Collins with
a separate mains supply.

Also, I would be glad to know if you've got any help from ICP for your RF
ammeter?


73,

Thierry

I contacted ICP but they do not have a spare meter to sell. Anyway I restored my
meter in some way. The thermocouple had blown up, so I replaced it with a 5-ohm
resistor across which I put a Shottky diode which measures RF voltage and,
hence, RF current. It works fine and I adjusted it for 250mA full scale, as the
original meter. Clearly the scale is not the same, but it is OK until I will
find a spare meter. Another uncertaintly is the resistor value, which should
ideally be the same as the original thermocouple, but I do not know how much it
was.

Yesterday I was able to finally get my ART-13 working. It delivers about 140 RF
on 7 MHz. Everything seems to work fine including the auto-tune system. Next
step will be to hook it up to a BC-348 receiver.

I am using a home-built power supply instead of the original dynamotor which is
very noisy. Not difficult to build. I have a transformer connected to a voltage
doubler which delivers about 1300V. Another transformer connected to a bridge
rectifier delivers about 400VDC. And finally the filament transformer connected
to a high-current bridge rectifier which delivers 28VDC at 9A. Plus two control
relays. Connections are rather easy. The only issue is to get the connector for
the ART-13 which is quite expensive (they typically sell it for about 50$).

In Italy we use the frequency of 7.190 kHz for AM, and one can find there many
AM aficionados on saturdays and sundays. I normally use a BC-191 hooked up to a
BC-312 receiver, and now I would like to try my ART-13 + BC-348.

73

Tony I0JX