You said that you fed in an external 10 mHz signal and it still doubled. Disregard all of the above. Look at the diodes across the input after the attenuator going into the FET's One of them could be bad which might halfwave rectify the input and cause the input to double in frequency. If they seem to be OK the look at the two FET's on the input. You might take a look at the signal at the two diodes. Also look at the output of the two FET"s
Ok, I checked the diodes with the DVM and they appear good. I then used the scope to check the signal at the FETs and when I looked at the display it was correct. It now reads exactly what it should. I have no idea what was wrong but it's now working. I hope it stays that way LOL. Thanks for jumping in, I wasn't even looking in that area.
@@ko2fjb Glad that you at least temporally fixed the problem. At the very least you have it narrowed down to a specific area. You might want to take a close look at the solder joints et around that area. It also might be prudent to hit some of the connections with an iron. Also look for hairline cracks in the pc board. Use a magnifying glass. Both sides of the board. Glad I could help.
The first thing i would look at is the 10 mHz oscillator. Look at waveform and frequency. It could be doubling for some reason. As memory serves it should be a sign wave and around 1 volt peek to peek . Do you have an O'scope? You should be able to see if it is doubling with that. I that is OK then look at the dividers for the time base these will be decade counters so should divide by 10 foe each range of the counter. 10mHz, 1mHz etc square wave. I don't think that your problem is that far down steam. because the count follows each range. I'm betting on the osc. Let me know what you discover .
Thanks John, I will double check that. I did insert 10 mhz into the external clock input and it was still double the input to the counter but I didn't actually check the output of the 10 MHz circuit, it's possible there is a discreet component that's bad. I will let you know what happens. Yes I do have a scope 😊.
Well, a viewer, John made some recommendations as to where to check, one being the input diodes and FETs. While probing that area with my scope it started working correctly. I did nothing other than probe the area so I have no idea what the problem was but it's still working today.
My fist guess was Harmonics but I guess that’s ruled out. 🤔
You said that you fed in an external 10 mHz signal and it still doubled. Disregard all of the above. Look at the diodes across the input after the attenuator going into the FET's One of them could be bad which might halfwave rectify the input and cause the input to double in frequency. If they seem to be OK the look at the two FET's on the input. You might take a look at the signal
at the two diodes. Also look at the output of the two FET"s
Thanks I'll work on that.
Ok, I checked the diodes with the DVM and they appear good. I then used the scope to check the signal at the FETs and when I looked at the display it was correct. It now reads exactly what it should.
I have no idea what was wrong but it's now working. I hope it stays that way LOL.
Thanks for jumping in, I wasn't even looking in that area.
@@ko2fjb Glad that you at least temporally fixed the problem. At the very least you have it narrowed down to a specific area. You might want to take a close look at the solder joints et around that area. It also might be prudent to hit some of the connections with an iron. Also look for hairline cracks in the pc board. Use a magnifying glass. Both sides of the board. Glad I could help.
The first thing i would look at is the 10 mHz oscillator. Look at waveform and frequency. It could be doubling for some reason. As memory serves it should be a sign wave and around 1 volt peek to peek . Do you have an O'scope? You should be able to see if it is doubling with that. I that is OK then look at the dividers for the time base these will be decade counters so should divide by 10 foe each range of the counter. 10mHz, 1mHz etc square wave. I don't think that your problem is that far down steam. because the count follows each range. I'm betting on the osc. Let me know what you discover .
Thanks John, I will double check that. I did insert 10 mhz into the external clock input and it was still double the input to the counter but I didn't actually check the output of the 10 MHz circuit, it's possible there is a discreet component that's bad.
I will let you know what happens. Yes I do have a scope 😊.
Counting half cycles instead of full cycles?
Well, a viewer, John made some recommendations as to where to check, one being the input diodes and FETs. While probing that area with my scope it started working correctly. I did nothing other than probe the area so I have no idea what the problem was but it's still working today.