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?

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 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

Tnx, Oh, I see, you calibrate the tuning dial by using the Xtal as a reference
knowing it is at the stated Xtal frequency when the magic eye peaks. I assume you
use the little knob next to the dial for this tweaking? or do you loosen the dial
and re-set it according to this calibration?

Bill K6TAJ

Dbowey wrote:

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

Tnx, Oh, I see, you calibrate the tuning dial by using the Xtal as a reference
knowing it is at the stated Xtal frequency when the magic eye peaks. I assume you
use the little knob next to the dial for this tweaking? or do you loosen the dial
and re-set it according to this calibration?

Bill K6TAJ

Dbowey wrote:

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

Tnx, Oh, I see, you calibrate the tuning dial by using the Xtal as a
reference
knowing it is at the stated Xtal frequency when the magic eye peaks. I assume
you
use the little knob next to the dial for this tweaking? or do you loosen the
dial
and re-set it according to this calibration?


Just turn the vfo freqency knob to see the zero beat, then lock it.

In ham use you would not usually use the crystal check/set feature, but you
could. The crystal's socket probably would accept an FT243 mounted crystal.

Don

Tnx, Oh, I see, you calibrate the tuning dial by using the Xtal as a
reference
knowing it is at the stated Xtal frequency when the magic eye peaks. I assume
you
use the little knob next to the dial for this tweaking? or do you loosen the
dial
and re-set it according to this calibration?


Just turn the vfo freqency knob to see the zero beat, then lock it.

In ham use you would not usually use the crystal check/set feature, but you
could. The crystal's socket probably would accept an FT243 mounted crystal.

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

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


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.783 / Virus Database: 529 - Release Date: 10/25/04