zeno wrote:
The one has already been modified, the other is relatively unmodified, but missing
the bottom and the top case.

Send me your mailing address.
I'll dig out a bottom and a top for your rig.

Concerning the power supply in the ARRL book-
It isn't the best design for the rig.
I'm putting together a couple of posts about all this
and will have them up shortly.

73 Dave S.

N2EY wrote:

In article , zeno writes:

Someone gave me an old ARC 5 (7-9.1) transmitter found at the county
dump. I would like to see if I can get it going on 40 meter CW.

First question is: What condition is it in?



The one has already been modified, the other is relatively unmodified, but missing
the bottom and the top case.





What does that conversion article show?

There was an article in the ARRL Handbooks for years that involved building an
external crystal oscillator in a minibox, using a 6AG7. Most of that article
was pretty good because it didn't hack up the ARC-5 too much (but it did
recommend destroying the power socket, unfortunately).


Yes, that is the article. I also have a power supply that works and has an octal
male plug as described in that article. I would have to add an octal female socket
on the back of the unmodified unit to receive this power supply plug. If I were to
attempt to put the modified unit back together I would need way more information
than I have at this point. For example the unmodified unit has an RF choke next to
the large vertical coil in from of the 1625s, on the modified unit, it looks like
it never had this rf choke installed. There are little wiring differences like
this in these two units which I do not understand. The vertical coil in the
unmodified unit has the red number 9295 printing on its edge, the modified unit
has the number 7250 on it. I do not know what this number means (?).

What (where would I get) information would I need to rebuild a totally modified
unit, to make it into some kind of an operating transmitter?



The Xtal in this unit is 8870 KC. Is this OK?

Not for ham operation!


The way I understand it, this is just for calibration of the VFO, so it is OK.




My original intention was to recreate a 50's style conversion of one of these
transmitters, however, I am not wondering if there is not a better way to go.

Bill k6TAJ

Bill posted:

Someone gave me an old ARC 5 (7-9.1) transmitter found at the county
dump. I would like to see if I can get it going on 40 meter CW. I have
found some information online, namely a schematic and an article for
"converting to Amateur use". I realize this is a crap shoot, but I
think it would be fun trying. I am trying to verify the wiring
according to this old schematic knowing that so many units have been
hacked into over the years. I have put together a power supply along
the lines of the reprinted "converting" article available at the ARRL
website. The Xtal in this unit is 8870 KC. Is this OK? How does this
Xtal function in this otherwise VFO unit, and what determines the
frequency that was chosen for this xtal? Other information or sources
of information would be welcome. Anyone else have any luck with these
things? Any recommendations?


You should not have any strange problems getting it running. The xtal was
selected for each mission. The crystal is used as a reference for setting the
VFO frequency. In the check position, the VFO and crystal oscillator are both
on, and when the vfo comes close to the crystal freq you will see the affect on
the tuning eye.

Have a ball.

Don

Bill, There is also a tuning eye tube in back of xmtr , the Xtal and
tuning eye is used to calibrate the VFO .You won`t need the Xtal or eye
tube for ham use.. I used an Arc 5 about 60 years ago on 40 mtrs. I had
pretty good output BUT it chirped like all crazy..there were several
schemes to get the chirp out, none of them worked very well..If you can
get the VFO to key without chirping it will be all OK. Good luck 73
Harold W4PQW

The ARC-5 transmitter is one of the great piece of electronics out of WWII.
As a kid, my first transmitter was an ARC-5 bought from JJ Glass of Los
Angeles for about $5.95. It was brand new and a beauty to behold. Getting
it working right will teach you everything that you need to know about
electronics (well as of 1957 anyway).

I was able to get mine to key nicely with no chirp at all. I still have a
wall full of them, they are nice to look at. You should be able to find a
schematic on the internet. I found that adjusting the oscillator plate
voltage to the individual transmitter could help solve a lot of problems and
regulated dc on the filaments does wonders, too. They will run 100 watts
without too much strain, although the power supplyis often twice the size of
the transmitter. But, they also run qrp on a much smaller supply and lower
voltage.

Have fun, Colin K7FM


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Nostalgia. When drafted into the Navy is 1943
my first job was setting up ARC-5 transmitters
and receivers in 336 SNJ (AT-6) aircraft. (among
other things) Later after the war when there wasn't
much money around, I would rewind ARC-5 receivers
and use them for ten-meter converters. In those days
tapping on the case of just about any transmitter or
receiver would produce some modulation. Except for
Collins equipment. The ARC-5 VHF transmitters were
truly awe inspiring when they arrived. 73s W6BWY

In article , zeno writes:

Someone gave me an old ARC 5 (7-9.1) transmitter found at the county
dump. I would like to see if I can get it going on 40 meter CW.

First question is: What condition is it in?

If it's in original unmodified condition, or close to it, please don't hack it
up. Unmodified ARC-5s *used to be* all over the place for low prices, and were
often subjected to all sorts of modifications. Some mods were pretty good, most
really weren't. IMHO, one that's survived this long in unmodified shape
deserves to be preserved. If you don't want to keep it historically accurate,
sell it to someone who does. There are plenty of hacked-up ones around to
experiment with.

OTOH, if it's been through the mods already (power socket changed, lots of
extra holes, coils rewound, paint largely gone, etc.) it might be OK to mod it
or use it as a parts source.

I have
found some information online, namely a schematic and an article for
"converting to Amateur use". I realize this is a crap shoot, but I
think it would be fun trying. I am trying to verify the wiring
according to this old schematic knowing that so many units have been
hacked into over the years. I have put together a power supply along
the lines of the reprinted "converting" article available at the ARRL
website.

What does that conversion article show?

There was an article in the ARRL Handbooks for years that involved building an
external crystal oscillator in a minibox, using a 6AG7. Most of that article
was pretty good because it didn't hack up the ARC-5 too much (but it did
recommend destroying the power socket, unfortunately).

The Xtal in this unit is 8870 KC. Is this OK?

Not for ham operation!

How does this
Xtal function in this otherwise VFO unit, and what determines the
frequency that was chosen for this xtal?

It allowed the dial to be checked against one known point, using the 1629
magic-eye tube. This was a simple check that could be done in the plane to be
sure that things weren't way off. ARC-5 transmitters (when used in small
planes) were usually meant to be adjusted on the ground by a technician, who
would then lock all the settings and the pilot would simply choose which
transmitter to use.

Other information or sources
of information would be welcome.

KG7BZ website, if it's still operational


Anyone else have any luck with these
things? Any recommendations?

They are an excellent example of 1930s radio engineering at its very best. They
did the job with a maximum of efficiency and a minimum of size, weight,
complexity and cost. The receivers are even better.

73 de Jim, N2EY

btw, about 12 years or so ago, a local ham showed me an intact BC-459. A little
dusty but completely untouched. He found it on someone's trash, wanted to know
if it was worth carting to the upcoming hamfest and if so, how much to ask. I
said $25 and he thought I was nuts. It was the first thing he sold.