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ARC 5 Transmitter
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 |
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