Read this thread
http://transmission1.net/viewtopic.php?t=54717
I can get readings from the points suggested but I can’t tune to 10.240 only 10.23984/10.23934
I’ve changed some caps and tried a different 10.240 crystal
Bit stuck
Crt hercule pll woes
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Re: Crt hercule pll woes
What exactly is the problem? If your 10.240 reference is 600hz off , that won't stop the radio from working .
30TM060
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
Paul aka "Sammy". (108) PY60 Old Paisley DX Group (RIP Rab Markie)
Ex GM0 , now EA5 .
Handle "Fortune Hunter" back in "the day"
Radios ....? Anything that says "TAIWAN R.O.C" on the back.
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Re: Crt hercule pll woes
Usually get them closer I wasn’t sure if there was a problem
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Re: Crt hercule pll woes
Two possibilities, you could be either loading the oscillator with your counter and causing a false low reading, or actually have a slightly low frequency there.
The 10.240 signal is used to synthesize the channel spacing (10.240 divided by 1024 = 10 KHz) so it can be indirectly measured (i.e. without connecting anything directly to the oscillator itself) by measuring the channel spacing.
Put it on AM channel 1, and set the the radio frequency to exactly 26.965.000, then change to channel 40 and measure again.
If it's slightly higher than 27.405.000 you were loading it and getting a false low reading. If it's slightly lower than 27.405.000 then 10.24 oscillator is actually lower.
Being only a few hundred hertz off, the frequency error on channel 40 might be insignificant and not worth the bother to correct it.
There is a 100pF cap connected to the crystal, reducing it to 82pF or 68pF will bring the frequency up a tad - but if you go too low the crystal may stop oscillating altogether...
The 10.240 signal is used to synthesize the channel spacing (10.240 divided by 1024 = 10 KHz) so it can be indirectly measured (i.e. without connecting anything directly to the oscillator itself) by measuring the channel spacing.
Put it on AM channel 1, and set the the radio frequency to exactly 26.965.000, then change to channel 40 and measure again.
If it's slightly higher than 27.405.000 you were loading it and getting a false low reading. If it's slightly lower than 27.405.000 then 10.24 oscillator is actually lower.
Being only a few hundred hertz off, the frequency error on channel 40 might be insignificant and not worth the bother to correct it.
There is a 100pF cap connected to the crystal, reducing it to 82pF or 68pF will bring the frequency up a tad - but if you go too low the crystal may stop oscillating altogether...
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Re: Crt hercule pll woes
Many thanks bud makes sense. Yes the radio is working ok as is
I can see why nick hates rangers now
I can see why nick hates rangers now
lbcomms wrote: ↑23 Feb 2019, 14:30 Two possibilities, you could be either loading the oscillator with your counter and causing a false low reading, or actually have a slightly low frequency there.
The 10.240 signal is used to synthesize the channel spacing (10.240 divided by 1024 = 10 KHz) so it can be indirectly measured (i.e. without connecting anything directly to the oscillator itself) by measuring the channel spacing.
Put it on AM channel 1, and set the the radio frequency to exactly 26.965.000, then change to channel 40 and measure again.
If it's slightly higher than 27.405.000 you were loading it and getting a false low reading. If it's slightly lower than 27.405.000 then 10.24 oscillator is actually lower.
Being only a few hundred hertz off, the frequency error on channel 40 might be insignificant and not worth the bother to correct it.
There is a 100pF cap connected to the crystal, reducing it to 82pF or 68pF will bring the frequency up a tad - but if you go too low the crystal may stop oscillating altogether...
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Re: Crt hercule pll woes
Plus it all depends on how accurate the counter is, if it is calibrated, when it was calbrated, and the sampling frequency.
160 Hz is nothing to worry about anyroad
160 Hz is nothing to worry about anyroad