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Gordon Gibby
¿ªÔÆÌåÓýHere is the relevant subroutine in the 7025 KHz sketch:
void setFrequency(unsigned long f) {
//? Want to tune to 7075 kHz
//? Intermediate frequency is 12 000 000?
//? Needed VFO freq is 12 000 000 -? 7075000 =? 4925000
f=4925000UL;
si5351bx_setfreq(2,f);
?
? updateDisplay();
}
? so you can see how it forces the frequency to 4925000? Hertz
From: [email protected] <[email protected]> on behalf of Gordon Gibby <ggibby@...>
Sent: Wednesday, December 20, 2017 12:13 AM To: [email protected] Subject: Re: [BITX20] Help! I think I may have just ruined my 9 year old's Chanukah ?
?The reason 12.000 MHz is important is that this is the crystal filter frequency (roughly) --- so the purpose of the VFO is to create a frequency that when added (or, subtracted one way or the other) with the DESIRED input frequency, a frequency of 12.00000MHz
can be created, which will then be SELECTED by the action of the narrow crystal filter.
Then, this internmediate frequency signal is mixed with a BFO (beatfrquency oscillator) signal right near (but a tiny bit higher than) 12.0000 MHz and the result is audio from the LOWER sideband of the intermediate frequency (12 Mhz) signal.? ??
I think I got that right.? ? ?
But the whole point was to indicate while you searched the right frequency range when trying Farhan's sketch, you DIDNT check the right frequency when trying the special sketch I sent you, because it generates a fixed VFO signal at 4.925 MHz and that is
where you would look for it.? ? (and it you FOUND it, the radio shouldbe locked onto receiving 7.075 MHz lower sideband.....if other sections of the radio worked)
Cheers!!!!
Gordon
From: [email protected] <[email protected]> on behalf of Gordon Gibby <ggibby@...>
Sent: Tuesday, December 19, 2017 11:59 PM To: [email protected] Subject: Re: [BITX20] Help! I think I may have just ruined my 9 year old's Chanukah ?
"It's a Yaesu FT-891. With the regular sketch, I looked for it from 4.8-5.5 mhz. With yours, I looked
for it about 200 below and 500 above 7.025 mhz
Isn't the Si5351 just a chip? Can't I just replace the chip?" ?1.? The sketch (I just sent it again to be safe) should force your Si5355 to product a 4.925 Mhz Signal.? ?So you would cozy the input coax center conductor ofyour radio up to the raduino output wiring and hunt around 4.925 MHz.? ? (When you add 4.925 + 7.075 MHz, you get 12.000 Mhz --- so that is the reason this VFO setting shoulld tune the BITX receiver to 7.075 MHz---- but you will NOT hear any signal from the bitx at 7.075 Mhz..... 2.? Si5151:? I had to actually go hunt for it.? ?I think it is a tiny surface mount chip with 5 leads on each side, making a total of 10 leads, soldered in.? ??
Gordon
From: [email protected] <[email protected]> on behalf of tausciam@... <tausciam@...>
Sent: Tuesday, December 19, 2017 11:47 PM To: [email protected] Subject: Re: [BITX20] Help! I think I may have just ruined my 9 year old's Chanukah ?
On Tue, Dec 19, 2017 at 08:38 pm, Gordon Gibby wrote:
It's a Yaesu FT-891. With the regular sketch, I looked for it from 4.8-5.5 mhz. With yours, I looked for it about 200 below and 500 above 7.025 mhz
Isn't the Si5351 just a chip? Can't I just replace the chip?
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