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dynamotor seems to be a little too much an outdated item by today's comfort,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