Frequency shifted ???

[doc john]

Help needed. I have a Cardon Iroqouis 40 ssb base which is similar to a Lafayette Telsat 140 ssb with the PLL02A freq. synthesizer. I got it working great and am getting really good reports on skip. But... I checked the frequencies yesterday because the lower channels seemed to be missing. What I found was that channels 28 to 40 are all normal, but channels 1 to 25 have been shifted. Channel 1 is actually channel 28 to channel 11 which is ch 40. Channels 12 to 25 are all above 27.405 with channel 25 reading 27.565. Any help would be appreciated.

 

[TM86]

Help needed. I have a Cardon Iroqouis 40 ssb base which is similar to a Lafayette Telsat 140 ssb with the PLL02A freq. synthesizer. I got it working great and am getting really good reports on skip. But... I checked the frequencies yesterday because the lower channels seemed to be missing. What I found was that channels 28 to 40 are all normal, but channels 1 to 25 have been shifted. Channel 1 is actually channel 28 to channel 11 which is ch 40. Channels 12 to 25 are all above 27.405 with channel 25 reading 27.565. Any help would be appreciated.

Just a guess, but it sounds like you're missing the +5v to pin 10 on the PLL02A that gets switched on for channels 1-27. If that's the case the most likely culprit is the channel selector, but it may just have some oxidation on the internal contacts rather than being broken. Could also just be a broken solder joint or a broken or cut trace somewhere between the switch and that pin.

 

[doc john]

Thanks TM86 I'll take a look at pin 10 for +5v, I thought maybe someone wanted to alter the freqs. on purpose.

 

[Captain Kilowatt]

Just a guess, but it sounds like you're missing the +5v to pin 10 on the PLL02A that gets switched on for channels 1-27. If that's the case the most likely culprit is the channel selector, but it may just have some oxidation on the internal contacts rather than being broken. Could also just be a broken solder joint or a broken or cut trace somewhere between the switch and that pin.

That would be my thought as well. I actually owned a Cardon Iroquois 40 many years ago. It was made by Midland and is identical to a Colt Black Shadow. It was a GREAT radio but with the PLL set up as it was it would not go below channel 1 without a crystal change out.

 

[doc john]

You guys were right! Thanks!! I checked the wiring from the switch to the wire wrap pin for pin 10 and found +5 volts Ch 1 to Ch 28. Then it hit me... I didn't actually check pin 10 on the chip itself. Sure enough no +5! Pulled the bottom plate, examined the pcb and there were two cut tracks. One for pin 10 and also pin 9. Once jumped the frequencies are correct Ch 1 is back to 26.965. Hey thanks a million! John
ps also made a good skip contact into Texas just to make sure all is AOK

 

[TM86]

You guys were right! Thanks!! I checked the wiring from the switch to the wire wrap pin for pin 10 and found +5 volts Ch 1 to Ch 28. Then it hit me... I didn't actually check pin 10 on the chip itself. Sure enough no +5! Pulled the bottom plate, examined the pcb and there were two cut tracks. One for pin 10 and also pin 9. Once jumped the frequencies are correct Ch 1 is back to 26.965. Hey thanks a million! John
ps also made a good skip contact into Texas just to make sure all is AOK

Good work getting it fixed!