RadioBanter - PS connections for NCX-3

RadioBanter (https://www.radiobanter.com/)

- Boatanchors (https://www.radiobanter.com/boatanchors/)

- - PS connections for NCX-3 (https://www.radiobanter.com/boatanchors/6700-ps-connections-ncx-3-a.html)

PS connections for NCX-3

I've got an NCX-3 HF xcvr with a fried power supply. The rig's PS
connector is a big, square 12-pole affair. The manual says the poles
are wired like this:

1 -- power switch
2 -- power switch
3 -- -80 volt bias @ 6ma
4 -- 12,6 volt heater @ 5a
5 -- speaker ground
6 -- common ground
7 -- speaker
9 -- +280 volt @ 125 ma
11 -- +700 volt @ 300ma

(the missing poles are unused)

My question: is it possible to fire this rig with my 25 amp Astron
2-pole 13.8 volt PS, and if so, how do I wire it to that big square
plug?

TNX,

Rob Henderson
KB7PWJ

See my article "Low Power, Crummy Antenna," QST, December 1999. PDF
file available from the ARRL website:

http://www.arrl.org/tis/info/pdf/9812057.pdf

RK Henderson ) writes:
I've got an NCX-3 HF xcvr with a fried power supply. The rig's PS
connector is a big, square 12-pole affair. The manual says the poles
are wired like this:

1 -- power switch
2 -- power switch
3 -- -80 volt bias @ 6ma
4 -- 12,6 volt heater @ 5a
5 -- speaker ground
6 -- common ground
7 -- speaker
9 -- +280 volt @ 125 ma
11 -- +700 volt @ 300ma

(the missing poles are unused)

My question: is it possible to fire this rig with my 25 amp Astron
2-pole 13.8 volt PS, and if so, how do I wire it to that big square
plug?

The only way a 12V supply could power that is if the rig was
set up to run off 12v.

There were tube rigs that had little DC to DC converters, built in or
as modules that plugged into the rig, so one could run them off 12v.

But that connector indicates no such thing. There is no place to
feed in just 12V DC, and the fact that it is expecting various voltages
is a good indicator that you need a complete power supply, that
will supply:

3 -- -80 volt bias @ 6ma
4 -- 12,6 volt heater @ 5a
9 -- +280 volt @ 125 ma
11 -- +700 volt @ 300ma

By making the power supply remote, it allows for much more flexibility.
You don't have to lug around a built in power supply, that might be
a waste if you only used the rig at home or in the car.

So you could choose between an AC supply, or a DC supply, and plug
either into that socket. Or, if you ran the rig in the car, leave
the DC supply there, and then bring the rig into the house and
connect it to the AC supply.

Michael

RK Henderson wrote:
I've got an NCX-3 HF xcvr with a fried power supply. The rig's PS
snip

Is the transformer of your power supply smoked?
(I assume it's the National a.c. supply type NCX-A).
If you are lucky, you may just have a bad
electrolytic capacitor causing fuses to pop immediately.

If the power transformer is still OK, the rest of the power supply
should be reparable.

73,
Ed Knobloch