I just got an ARC 5 receiver and wonder if anyone has any tips on modifying
it; I had one in the 1960's, but can't remember what I had to do to it. I
think I replaced the dynamoter plug with a modern one, but dont remember how
I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV

Rewire the filaments from 24 volt configuration to 12 volts.

You need +250 for plate voltage.

It's been 50+ years since I modified one, so I don't know the pin assignments.

/s/ DD



genev wrote:

I just got an ARC 5 receiver and wonder if anyone has any tips on modifying
it; I had one in the 1960's, but can't remember what I had to do to it. I
think I replaced the dynamoter plug with a modern one, but dont remember how
I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV

Dave wrote:
Rewire the filaments from 24 volt configuration to 12 volts.

You need +250 for plate voltage.

It's been 50+ years since I modified one, so I don't know the pin
assignments.

/s/ DD



genev wrote:

I just got an ARC 5 receiver and wonder if anyone has any tips on
modifying it; I had one in the 1960's, but can't remember what I had
to do to it. I think I replaced the dynamoter plug with a modern one,
but dont remember how I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV



Hi!
The tuning needs a special socket in a splined multi pointed star formation.
The best source is of course the original remote cables, but finding
those would be a minor miracle by now. It just might be possible, if you
have well stocked hardware store near you to find a nearly identical
socket which could be made to fit. Don't forget the output impeadance of
the audio transformer is about 200 ohms to match the original crew
headsets. Actually by now I reckon that you might find that a lot of the
bypass and coupling caps in the cans along either side of the chassis
are leaky and may need replacing.
I'm not sure which RX you have, there are actually about 5 or 6
versions. The Hf ones above 3 MHz or so are very lacking in selectivity
with an IF frequency of 1.4 or 2.6 (I think) MHz.
I still have one of my first homebrew Ham RX's that I made back in the
1960's when I first came out to NZ.
It was a triple superhet, Ist IF tunable from 3.5-4MHz, 2nd IF 2xARC5
IFT's at 1.4MHZ and 3rd IF 2 stages of 85KHz using "Q5er" ARC5
transformers with 6 tuned circuits.
Worked very well but did have some image problems 2.8 MHz away from the
wanted signal.
Hope you can get it all going OK. I sem to remember several ideas
published back in the 1960's and 50's which you might be able to trace
on the web.
73's
Cliff Wright ZL1BDA ex G3NIA.

In the 50s I used to make the tuning knob shaft with a piece of car
radio antenna that fit and filled it palster of paris and pushed it and
let it harden. It's removeable but I'll bet there are some better
synthetics available today. I see the splines selling for $5 top $10 on
ePay.

--

73
Hank WD5JFR
"cliff wright" wrote in message
...
Dave wrote:
Rewire the filaments from 24 volt configuration to 12 volts.

You need +250 for plate voltage.

It's been 50+ years since I modified one, so I don't know the pin
assignments.

/s/ DD



genev wrote:

I just got an ARC 5 receiver and wonder if anyone has any tips on
modifying it; I had one in the 1960's, but can't remember what I had
to do to it. I think I replaced the dynamoter plug with a modern
one, but dont remember how I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV



Hi!
The tuning needs a special socket in a splined multi pointed star
formation.
The best source is of course the original remote cables, but finding
those would be a minor miracle by now. It just might be possible, if
you have well stocked hardware store near you to find a nearly
identical socket which could be made to fit. Don't forget the output
impeadance of the audio transformer is about 200 ohms to match the
original crew headsets. Actually by now I reckon that you might find
that a lot of the bypass and coupling caps in the cans along either
side of the chassis are leaky and may need replacing.
I'm not sure which RX you have, there are actually about 5 or 6
versions. The Hf ones above 3 MHz or so are very lacking in
selectivity
with an IF frequency of 1.4 or 2.6 (I think) MHz.
I still have one of my first homebrew Ham RX's that I made back in the
1960's when I first came out to NZ.
It was a triple superhet, Ist IF tunable from 3.5-4MHz, 2nd IF 2xARC5
IFT's at 1.4MHZ and 3rd IF 2 stages of 85KHz using "Q5er" ARC5
transformers with 6 tuned circuits.
Worked very well but did have some image problems 2.8 MHz away from
the wanted signal.
Hope you can get it all going OK. I sem to remember several ideas
published back in the 1960's and 50's which you might be able to trace
on the web.
73's
Cliff Wright ZL1BDA ex G3NIA.

For a tuning knob you can use an old tv or radio knob, the type that
fit on the shaft that was split and had splines on it. Most of those
old knobw will fit on the arc 5.

Another way to do it is to remove the shell that is around the tuning
shaft. That will allow you to put a 1/4 inch shaft coupling on the arc
5 shaft. Then put a short shaft and knob on the other end and you are
all set.

73
Gary K4FMX

On Wed, 28 Feb 2007 19:31:11 +1300, cliff wright
wrote:

Dave wrote:
Rewire the filaments from 24 volt configuration to 12 volts.

You need +250 for plate voltage.

It's been 50+ years since I modified one, so I don't know the pin
assignments.

/s/ DD



genev wrote:

I just got an ARC 5 receiver and wonder if anyone has any tips on
modifying it; I had one in the 1960's, but can't remember what I had
to do to it. I think I replaced the dynamoter plug with a modern one,
but dont remember how I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV



Hi!
The tuning needs a special socket in a splined multi pointed star formation.
The best source is of course the original remote cables, but finding
those would be a minor miracle by now. It just might be possible, if you
have well stocked hardware store near you to find a nearly identical
socket which could be made to fit. Don't forget the output impeadance of
the audio transformer is about 200 ohms to match the original crew
headsets. Actually by now I reckon that you might find that a lot of the
bypass and coupling caps in the cans along either side of the chassis
are leaky and may need replacing.
I'm not sure which RX you have, there are actually about 5 or 6
versions. The Hf ones above 3 MHz or so are very lacking in selectivity
with an IF frequency of 1.4 or 2.6 (I think) MHz.
I still have one of my first homebrew Ham RX's that I made back in the
1960's when I first came out to NZ.
It was a triple superhet, Ist IF tunable from 3.5-4MHz, 2nd IF 2xARC5
IFT's at 1.4MHZ and 3rd IF 2 stages of 85KHz using "Q5er" ARC5
transformers with 6 tuned circuits.
Worked very well but did have some image problems 2.8 MHz away from the
wanted signal.
Hope you can get it all going OK. I sem to remember several ideas
published back in the 1960's and 50's which you might be able to trace
on the web.
73's
Cliff Wright ZL1BDA ex G3NIA.

Hi

I managed to pick up an almost new ARC5 receiver a year ago and later
found a dynamotor. The set worked well for a bit then popped a smoothing
cap. My suggestion is to run on much lower HT (I have heard that these
sets might even work on 28v HT). I don't like modifying classic antique
sets such as these that are now getting harder to find - it immediately
reduces the value by over half apart from anything else, especially if
the front is altered as many were.

Tuning knobs can be found on internet auction sites, but even a short
piece of thin stiff plastic tubing slipped over the splines with some
solid rod inserted the other end and a knob will work.

There were many conversion articles/books written in the 1950s which
sometimes turn up at radio sales or auctions but these usually show
major mods to create a cheap and useful piece of ham radio gear. But
times have changed.

Simon VK2UA

genev wrote:
I just got an ARC 5 receiver and wonder if anyone has any tips on modifying
it; I had one in the 1960's, but can't remember what I had to do to it. I
think I replaced the dynamoter plug with a modern one, but dont remember how
I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV

On Feb 27, 8:53 pm, "genev" wrote:
I just got an ARC 5 receiver and wonder if anyone has any tips on modifying
it; I had one in the 1960's, but can't remember what I had to do to it. I
think I replaced the dynamoter plug with a modern one, but dont remember how
I put the tuning knob on the front.
Also, what voltages are needed?
Thanks in advance for any info.
Richard
K1TAV


Richard. If your ARC-5 is original my strong suggestion is to not
modify the radio itself, except to fit some kind of tuning knob to
where the tuning cable was originally attached. You don't mention what
frequencies yours tunes. The most valuable model covers the broadcast
band. In mint (unchopped) condition some of those have sold recently
for over $100! And value is rising. Other frequency, unmodified ARC-5
often command $50 or higher.

It is not necessary to modify the receiver itself. I had one at around
age 14 which operated with an outboard power supply etc. the ARC-5
being completely untouched. It was my first superhet radio.

Information is readily available from other enthusiasts and on the web
about connections. I could forward some info if you wish.

Many of the 'chop jobs' done when these receivers were commonly
available (And cheap, sometimes as little as four dollars etc.) were a
shame and substantially reduced their value without improving the
ability of the receiver to work just as well as it did when installed
in an aircraft.

As you mentioned there is a 3 pin dynamotor plug on the back. You can
either connect wires to that to power the radio or power it via the
socket at the back. I have found that certain sizes of those blue
shelled crimped 'wire splicers/joiners ' commonly used to join say car
wiring will slip nicely and fit over those pins without destroying
them (some types will; some won't so experiment a bit) I do hope
somebody has not soldered to yours. It ruins them!

The sockets and plugs on those radios are a beautiful job of metal
pins mounted in mica. Some people have chopped them out and installed
various other types such as an octal etc. Some people have been able
to find an ex dynamotor base, or have made, a suitable base plate on
to which they have a mounted a small power supply; not very hard to
do. The advice about running the radios at much lower than the
original 250 volts DC B+ that the dynamotor put out seems to be very
good indeed. because the metal cased capacitors inside the base now
60+ years old can deteriorate, sometimes leak and/or short circuit.
have a fuse in the power supply no matter how you power it. Once or
twice power supplies specifically for that purpose have been seen on
eBay.

The 12 volt tubes are wired in three pairs so as to work on the 24 to
28 volt DC aircraft supply, so that heater current requirement is 3 x
0.15 = 0.45 amps at 24 volts. The 28 volts also powered the dynamotor
on the back of each ARC-5 receiver. Radio Shack used to sell small 115
volt input transformers that put out 24 volts at more than sufficient
amperage However many enthusiasts have transformer lying around that
may be suitable for the heater circuit and to provide B+. If you do
'have' to modify the heater circuit to 12 volts it will require about
0.9 amps. AC for the heaters is fine.

Even if done neatly other modifications to the front of the radio to
add a) RF gain control b) CW BFO on/off switch and sometimes also a
phone jack, usually involved butchering the plug in unit that goes in
the front secured by four small screws. It usually wasn't possible to
fit the controls into the small box that comes out so it and the
screened area behind it was often chopped out.

Some are lucky to have a one, two, or three position slide in plug in
rack into which these radios were mounted in the aircraft. They are
not very common now so it is usually necessary to connect wires in
some manner to the connector socket on the back of the receiver
itself. Best, if possible, to use some sort of small plugs to avoid
damaging the socket.

Somebody mentioned the gauge of wire that will just neatly plug into
each socket; maybe it was #6 or #8 AWG, I'll try and measure which
size fits firmly and tidily. And advise here.

From memory to get the radio to work it is necessary to provide power.
An RF gain potentiometer (no AF volume control was provided) and
provide a switch to ground (IIRC) the BFO oscillator lead. Another
caution is check whether the output transformer, which fed aircraft
headphones directly or the aircraft intercom system, could be set, on
most models for either low (600 ohm?) or (6000 impedance?) required
soldering inside IIRC. Volume output may seem low if set to high
impedance.

As mentioned a lot of this is from memory; I have six of those radios
downstairs but haven't worked on them since the 1950s! Three of mine
have been 'got at' and three are almost pristine but are all the same
frequency coverage.

There are most likley many people around who will have better
information; but am rushing this reply in order to encourage and urge
you from unnecessarily 'butchering' yet another 'Command' receiver as
so many were in the past.

As advised it is completely possible and was quite common to have a
power supply and all controls neatly outboard and to not have to chop
up the ARC-5 radio at all. One advantage being that if one then
acquired another ARC-5 it was not necessary to also modify it! Just
plug into the same power supply etc. and head phones, attach the
antenna and away you go.

Another seemingly unnecessary mod. that has been seen is that which
replaces the output circuit to provide enough power to feed a
speaker. The out put tube is a 12A6 which could provide sufficient
audio output. But attempts to do so often burnt out the primary
winding of the original 'potted' output transformer in the plate
circuit of the 12A6 tube. That led to replacement, inboard and
outboard OP transformers and sometimes the displacement of of other
parts. In one case someone added another tube on the back of the set
in a most untidy fashion!

If I can provide additional info which I have somewhere please
contact me. Again I urge, do not make unnecessary alterations.
Terry.

"terryS" ) writes:

Many of the 'chop jobs' done when these receivers were commonly
available (And cheap, sometimes as little as four dollars etc.) were a
shame and substantially reduced their value without improving the
ability of the receiver to work just as well as it did when installed
in an aircraft.

But this is revisionist history.

Nobody has an obligation to keep things intact for some potential
point down the road.

Those things were cheap and plentiful back then. Even in 1972, I could
get a Command Set transmitter for ten dollars, which meant that modifying
it to be a VFO was a far better choice than buying parts and making a VFO.
If you got it for ten dollars, who cares about resale value? Especially
when you could turn around and get another. If they'd carried a higher
price back then, obviously people would have thought twice about it,
because their appeal would be less. But they were so plentiful that they
were practically given away, so it was perfectly fine to do whatever you
wanted to do with them, even if it meant stripping it down and basically
using the chassis and variable capacitor(s) for something drastically
different, like a homebrew receiver or SSB transmitter.

Obviously it's all a different matter, now that they have become scarce.
But it's now over sixty years after WWII ended. And of course, if people
hadn't been making use of them, doing whatever they wanted to do with
them, then the numbers wouldn't have dropped, and while some might consider
them valuable, nobody could get high money for them, because they'd still
be plentiful.

But it's silly today to be critical of what was done to them back then
because things are meant to be used. We bought comic books and read them
and wore them out and threw them out; we didn't keep them in plastic and
never read them. We bought equipment and put it to use, and if things
weren't to our liking, modified them, and if things broke down, they
got fixed and nobody felt a need to keep things exact. And people got
value out of all that surplus equipment that came out of WWII, precisely
because it was cheap and in large quantities. Because things are made
to be used.

Michael VE2BVW

On Mar 3, 4:08 pm, (Michael Black) wrote:

But it's silly today to be critical of what was done to them back then
because things are meant to be used. We bought comic books and read them
and wore them out and threw them out; we didn't keep them in plastic and
never read them. We bought equipment and put it to use, and if things
weren't to our liking, modified them, and if things broke down, they
got fixed and nobody felt a need to keep things exact. And people got
value out of all that surplus equipment that came out of WWII, precisely
because it was cheap and in large quantities. Because things are made
to be used. Michael VE2BVW
..
That was then. This is now. Comments were written in the vein of
vintage radio preservation ; and what are 'Boat Anchors' and any
interest in them, but vintage items? There are probably not that many
'unchopped' Command units around now.
If you want modern go buy an Ipod, cell phone or satellite DAB
receiver etc.
Preservation too not for the dollar value but the aesthetic and
cultural value of having at least a few of items of historic interest,
in as original form as possible.
But also to look at $ value; of vintage cars, for example. Especially
if in good restored condition and especially if all the vehicle serial
numbers match!
And particularly when it is not 'necessary' now to chop up older
radios. Even if you don't have one of those aircraft mounting Command
Set racks (Which came AIUI in 1,2 and 3 set versions) it is possible
to have very neat non-intrusive out board arrangements.
I recall for example that postwar one could buy a power transformer
specifically for these sets with a 24 volt heater winding. Although
there are a number of ways of obtaining that voltage.
In the early 1950s, as an untrained and not very skilled 14 year old,
made a separate power supply (in a vented wood and Masonite box with a
B+ milliammeter IIRC) and out boarded the RF gain, CW switch and
headphone connections. My beautifully made BC455 was untouched!
Have fun.