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

On Thu, 15 Jul 2004 01:28:53 UTC, (RK Henderson)
wrote:

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?

Not possible. Hit eBay or a big hamfest and find a Heathkit HP23,
any model. 23, 23A, 23B, etc. Should be about $50.

What's wrong with the NCX=3's power supply? If the transformer is
OK, you can fix the rest of it for a couple dollars. If the
transformer is bad, it's essentially a basket case unless you feel
like rewinding it.

de ah6gi/4


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 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

(RK Henderson) wrote in message . com...

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?

It would seem better to locate or clone the correct NCX-3's mobile SS
12v supply/similar; surprised to hear some say it can't be run of 12v
as-is when it was designed to do so. FWIW I have both supplies & the
rig (not interested in separating) - the mobile supply is compact &
fairly simple AIRC from its schem. Wouldn't mind parting with it cplt
for a tempting offer (not a giveaway).

) writes:
(RK Henderson) wrote in message . com...

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?

It would seem better to locate or clone the correct NCX-3's mobile SS
12v supply/similar; surprised to hear some say it can't be run of 12v
as-is when it was designed to do so. FWIW I have both supplies & the
rig (not interested in separating) - the mobile supply is compact &
fairly simple AIRC from its schem. Wouldn't mind parting with it cplt
for a tempting offer (not a giveaway).

Of course it can't be run off 12v as is; you even state that when you
talke about getting the mobile supply.

He wanted to know if he could apply his 12V dc output from his power
supply the the NCX-3 and run the transceiver. And the answer is no,
it needs the mobile supply.

At that point, unless one wants to run it in the car, he is better off
buying or building an AC supply for the thing.

Michael VE2BVW

On Thu, 1 Jan 1970 01:59:59, wrote:

(RK Henderson) wrote in message . com...

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?

It would seem better to locate or clone the correct NCX-3's mobile SS
12v supply/similar; surprised to hear some say it can't be run of 12v
as-is when it was designed to do so. FWIW I have both supplies & the
rig (not interested in separating) - the mobile supply is compact &
fairly simple AIRC from its schem. Wouldn't mind parting with it cplt
for a tempting offer (not a giveaway).

huh? He asked if he could wire his 2-pole 13.8 PS to the square
plug on the back of the NCX3. The answer is no.

My advice is to get a Heath HP-13. These are about $50 on the Bay
and very plentiful. I have two for my 3 SB transceivers, so that
leaves one extra out there.

I'm not itching to get another HP-13 either as I have the Heath DC
supply and as you point out, I could use a big 12 V supply to run
the transceiver using it.

I'm sticking to my (and the others) point. If the NCX AC supply's
transformer is good, fix whatever else is wrong. A bad cap or
diode, a bad switch, whatever. Everything else in there should be
cheap and simple to fix.

If the transformer is bad, sell it on eBay as "Bad Transformer -
Full disclosure" Someone will buy it for the case or will take a
shot at fixing the transformer. Get a Heath. Folk use the Heath
for everything.

de ah6gi/4