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

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

In article , zeno writes:

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?

All the xtal tells you is whether the dial is close or not. Recalibration is a
shop procedure. The dial is pinned - don't try to change it.

The little knobs next to each control are locks to prevent the settings from
changing in flight.

73 de Jim, N2EY

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

In article , zeno writes:

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?

All the xtal tells you is whether the dial is close or not. Recalibration is a
shop procedure. The dial is pinned - don't try to change it.

The little knobs next to each control are locks to prevent the settings from
changing in flight.

73 de Jim, N2EY

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

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

why would you not need to use the Xtal to calibrate the VFO for ham use?

Bill K6TAJ

wrote:

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