Power Mod for AN/GRC-9
 

OK perhaps I should have said the wiring on the plug will be
transposed :))
But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??
from Ron...


On Wed, 29 Oct 2003 11:40:36 GMT, (Ron)
wrote:

AA/GRC-9 Mod
Hi I have recently bought one of these sets
and like most I expect have no PSU or Power Plug
However I did find an old Hand crank unit on its
own with no handles or tripod for a couple of pounds
And worked out a nice little mod to power up the set :))
Take all the nuts and bolts off the generator case and remove the
generator undo the psu connector leads making
sure you keep a note of where the wires go, unbolt the
dynamo generator and crank system and bin it.
take the power socket to pieces and remove the brass fixing
ring and reverse the housing this now makes the plug to fit
the Radios power connector (smart eh) you even have a plastic
cover to make it look neat
we now have a power plug with all the right connections..
The generator was just a dynamo so find where the 450v wires
came from it and connect to a 450 volts DC supply to the generator
chassis
and the same for 6.3 volt wires to a 6.3volt DC supply these
could be made up on a small chassis fitted where the dynamo was.
In theory it should all fire up with all the correct voltages!!!
I havn't tried the last bit yet but the plug bit certainly
works, and I'm just about to test it :))
good fun...
From Ron...

OK perhaps I should have said the wiring on the plug will be
transposed :))
But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??
from Ron...


On Wed, 29 Oct 2003 11:40:36 GMT, (Ron)
wrote:

AA/GRC-9 Mod
Hi I have recently bought one of these sets
and like most I expect have no PSU or Power Plug
However I did find an old Hand crank unit on its
own with no handles or tripod for a couple of pounds
And worked out a nice little mod to power up the set :))
Take all the nuts and bolts off the generator case and remove the
generator undo the psu connector leads making
sure you keep a note of where the wires go, unbolt the
dynamo generator and crank system and bin it.
take the power socket to pieces and remove the brass fixing
ring and reverse the housing this now makes the plug to fit
the Radios power connector (smart eh) you even have a plastic
cover to make it look neat
we now have a power plug with all the right connections..
The generator was just a dynamo so find where the 450v wires
came from it and connect to a 450 volts DC supply to the generator
chassis
and the same for 6.3 volt wires to a 6.3volt DC supply these
could be made up on a small chassis fitted where the dynamo was.
In theory it should all fire up with all the correct voltages!!!
I havn't tried the last bit yet but the plug bit certainly
works, and I'm just about to test it :))
good fun...
From Ron...

ALSO :) What does the K102 relay do???
I't a bit of a problem at the moment it seems to cut off the screen
grid supply to the PA at odd times?
Is it some sort of protection device?
from Ron...


On Thu, 30 Oct 2003 10:09:00 GMT, (Ron)
wrote:


OK perhaps I should have said the wiring on the plug will be
transposed :))
But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??
from Ron...


On Wed, 29 Oct 2003 11:40:36 GMT, (Ron)
wrote:

AA/GRC-9 Mod
Hi I have recently bought one of these sets
and like most I expect have no PSU or Power Plug
However I did find an old Hand crank unit on its
own with no handles or tripod for a couple of pounds
And worked out a nice little mod to power up the set :))
Take all the nuts and bolts off the generator case and remove the
generator undo the psu connector leads making
sure you keep a note of where the wires go, unbolt the
dynamo generator and crank system and bin it.
take the power socket to pieces and remove the brass fixing
ring and reverse the housing this now makes the plug to fit
the Radios power connector (smart eh) you even have a plastic
cover to make it look neat
we now have a power plug with all the right connections..
The generator was just a dynamo so find where the 450v wires
came from it and connect to a 450 volts DC supply to the generator
chassis
and the same for 6.3 volt wires to a 6.3volt DC supply these
could be made up on a small chassis fitted where the dynamo was.
In theory it should all fire up with all the correct voltages!!!
I havn't tried the last bit yet but the plug bit certainly
works, and I'm just about to test it :))
good fun...
From Ron...

ALSO :) What does the K102 relay do???
I't a bit of a problem at the moment it seems to cut off the screen
grid supply to the PA at odd times?
Is it some sort of protection device?
from Ron...


On Thu, 30 Oct 2003 10:09:00 GMT, (Ron)
wrote:


OK perhaps I should have said the wiring on the plug will be
transposed :))
But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??
from Ron...


On Wed, 29 Oct 2003 11:40:36 GMT, (Ron)
wrote:

AA/GRC-9 Mod
Hi I have recently bought one of these sets
and like most I expect have no PSU or Power Plug
However I did find an old Hand crank unit on its
own with no handles or tripod for a couple of pounds
And worked out a nice little mod to power up the set :))
Take all the nuts and bolts off the generator case and remove the
generator undo the psu connector leads making
sure you keep a note of where the wires go, unbolt the
dynamo generator and crank system and bin it.
take the power socket to pieces and remove the brass fixing
ring and reverse the housing this now makes the plug to fit
the Radios power connector (smart eh) you even have a plastic
cover to make it look neat
we now have a power plug with all the right connections..
The generator was just a dynamo so find where the 450v wires
came from it and connect to a 450 volts DC supply to the generator
chassis
and the same for 6.3 volt wires to a 6.3volt DC supply these
could be made up on a small chassis fitted where the dynamo was.
In theory it should all fire up with all the correct voltages!!!
I havn't tried the last bit yet but the plug bit certainly
works, and I'm just about to test it :))
good fun...
From Ron...

In article ,
(Ron) writes:

But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??

I still don't know if we're talking about the same radio -- mine has a big cast
dial with adjustable tab stops around it, and was half of a Tx/Rx combo in one
case. If I knew where to look, I'd go check its model number :-)

But ISTR that in mine, the heater is indeed 3V, and the 8-plus tubes are wired
in parallel-series. Four 1.4V tubes in parallel, in series with the other
four, and the 3V tubes wired across the whole thing, maybe with their center
tap connected to the "floating" junction of the two parallel strings. But
don't take my word for *anything*!

The usual trick when dealing with a 3V tube, when running from 1.4V source, is,
as you know, to power both sides of the filament and ground the center tap.
Hope this helps -- Mike K.

Oscar loves trash, but hates Spam! Delete him to reply to me.

In article ,
(Ron) writes:

But it works!! the 1.4volt heater has lead me astray, seems its
not 1.4volt but actually 3volt? the 3A4's in the Tx have a tapped
filiment I think, working a bit in the dark here, anyone else familiar
with these old beasts??

I still don't know if we're talking about the same radio -- mine has a big cast
dial with adjustable tab stops around it, and was half of a Tx/Rx combo in one
case. If I knew where to look, I'd go check its model number :-)

But ISTR that in mine, the heater is indeed 3V, and the 8-plus tubes are wired
in parallel-series. Four 1.4V tubes in parallel, in series with the other
four, and the 3V tubes wired across the whole thing, maybe with their center
tap connected to the "floating" junction of the two parallel strings. But
don't take my word for *anything*!

The usual trick when dealing with a 3V tube, when running from 1.4V source, is,
as you know, to power both sides of the filament and ground the center tap.
Hope this helps -- Mike K.

Oscar loves trash, but hates Spam! Delete him to reply to me.