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baconater4749
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¿???????????????????????????Now what did I do, I'm looking, and I think I may have found the Varsctor diode? Would it be connected to solder, under the VFO, next to the 10.240 final?- I saw what you did!
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Diagnosing a bad crystal? Need ideas on helping me and others.
- Thread starter Mark A Bradley
- Start date
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baconater4749
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baconater4749
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The 2nd post of this makes more sense - yes, one varactor by the 10.240 Xtal - at least you have one.
Don't forget to check and repair those resistors R85 and R88 if you need to - they look pretty hammered in the photos you've posted here.
Transistor Radio, Tomato's - et al.
Don't forget to check and repair those resistors R85 and R88 if you need to - they look pretty hammered in the photos you've posted here.
You answered within the quotes - so that is why I said that - I did see what you did. (Wrote really)
Transistor Radio, Tomato's - et al.
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baconater4749
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I removed the problem, and repairing it. Here is a Pic I think of the issue, as the Yellow and Black wires were melted together. I Un stuck them, after I removed it.WAIT,, new problem, look at the Resistor I found, I must be blind, right in fro t if me? Look closely looks cut?, yes, no,, what you think?
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baconater4749
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I have no idea how they were melted together, not my radio, my Buddies. He messes with these, I told him to keep his paws out of the Bt, it works, or worked great.
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baconater4749
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baconater4749
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I found mine in various sites most of the ones I needed.
But then too, this DEPENDS on the amount of capacitance you can use in the circuit.
IN the Cobra 25, they went with about 8pF to 22pF in a 5V ~16V PIV range - the PLL itself will only go as high at 4.5V - so when looking at ratings - try to find one with a good upper level of pF per the Voltage.
The parts in PDF's attached might still be available from various suppliers.
You also can "pad" extra capacitance alongside the Diode in line with the PLL feeder to it to ADD a starting value which lowers the starting frequency by increasing the capacitance (changes the MUF) - this may help in providing a level of stability inclusive to make the radios' VCO "Fire" easily and sill have some control range.
When you "stack" caps in parallel - their working frequency range changes - much like how you would use them to tweak the Xtals in CB's to more closely match the 10kHz spread, in the 5kHz (Nickels)
But then too, this DEPENDS on the amount of capacitance you can use in the circuit.
IN the Cobra 25, they went with about 8pF to 22pF in a 5V ~16V PIV range - the PLL itself will only go as high at 4.5V - so when looking at ratings - try to find one with a good upper level of pF per the Voltage.
The parts in PDF's attached might still be available from various suppliers.
You also can "pad" extra capacitance alongside the Diode in line with the PLL feeder to it to ADD a starting value which lowers the starting frequency by increasing the capacitance (changes the MUF) - this may help in providing a level of stability inclusive to make the radios' VCO "Fire" easily and sill have some control range.
When you "stack" caps in parallel - their working frequency range changes - much like how you would use them to tweak the Xtals in CB's to more closely match the 10kHz spread, in the 5kHz (Nickels)
Thank you,you know I just realized this is the radio that has that ugly looking channel modification board in it, and it has a 14.91MHz and a 15.81MHz crystals on the expansion board. Ok, now, how do I go about setting the primary frequency with these on the radio. I noticed now,that the Delta Tune is a 3 stop switch,it stops in left,center,and right,this is crazy.And as I play around, the SWR CAL opens as a Clarifier, it is moving the frequency 5 kc, not much,maybe 1 full channel I can get,slides to the next channel,this is wacky. This on a AM 40 channel,AM, what a waste,need it on a SSB radio,not this.
Well,any idea,what frequency do I start with,having 3 40 channel Radios on 1 switch,where do I start.I am being honest with you, I did not realize that this was a radio with extras. Now what,I have 3 different frequencies 26.284mhz,and I hear static,middle of switch,13.233 to 16.695 switch left ,28.778. totally lost here.
Well,any idea,what frequency do I start with,having 3 40 channel Radios on 1 switch,where do I start.I am being honest with you, I did not realize that this was a radio with extras. Now what,I have 3 different frequencies 26.284mhz,and I hear static,middle of switch,13.233 to 16.695 switch left ,28.778. totally lost here.
This goes back to another radio located in this thread...
https://www.worldwidedx.com/threads/need-alignment-frequencies-points.262137/page-2#post-767855
Not sure what is going on here but your 29's got a Delta tune - if it says it on the faceplate. Then the radio has a provision for it.
Delta Tune is a forward throw - from the older days of Crystal Synthesis radios were used, a 3-pole switch operated Crystals of specific frequencies and in doing so, kinda made a mess with alignments of all radios with all these Crystals - using physical parts that unless kept in a clean work environment - didn't always work well.
Back to the Drawing board...They made a feature that allowed those other radios with Crystals slightly off in frequency - to adjust their receiver to hear that slightly off station better - that's where the "Delta Tune" came in - a 3 position switch used to trim the a main receive crystal to resonate slightly faster or slower to help find those lost operators.
Not all radios used Delta Tune - in later years they fixed it (made it a fixed frequency like your typical radio could be) and installed a Dimmer to adjust brightness of the front panel - 29 Night Watch - to replace that knob. Others, like Class and LTD - used Delta Tune - still to this day. For now.
For best "recovery" you really should locate and remove the 3 band board.
Then - correctly rewire it, fix it, meaning - your radio - get it working right, then re-install the channel board.
https://www.worldwidedx.com/threads/need-alignment-frequencies-points.262137/page-2#post-767855
Not sure what is going on here but your 29's got a Delta tune - if it says it on the faceplate. Then the radio has a provision for it.
Delta Tune is a forward throw - from the older days of Crystal Synthesis radios were used, a 3-pole switch operated Crystals of specific frequencies and in doing so, kinda made a mess with alignments of all radios with all these Crystals - using physical parts that unless kept in a clean work environment - didn't always work well.
Back to the Drawing board...They made a feature that allowed those other radios with Crystals slightly off in frequency - to adjust their receiver to hear that slightly off station better - that's where the "Delta Tune" came in - a 3 position switch used to trim the a main receive crystal to resonate slightly faster or slower to help find those lost operators.
Not all radios used Delta Tune - in later years they fixed it (made it a fixed frequency like your typical radio could be) and installed a Dimmer to adjust brightness of the front panel - 29 Night Watch - to replace that knob. Others, like Class and LTD - used Delta Tune - still to this day. For now.
For best "recovery" you really should locate and remove the 3 band board.
Then - correctly rewire it, fix it, meaning - your radio - get it working right, then re-install the channel board.
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