K1 internal signal generator?

[Craig Rairdin]

The K1 manual makes a very, very brief mention of using an internally
generated signal to calibrate the receiver. It seems to indicate this signal
is at "99.7". With an antenna disconnected I hear a carrier that is
definitely in the neighborhood of "99.7" on 40, 20, and 15M, but on 30M I
don't hear it. OTOH, I set it up with 10.1 MHz as the low end of that band
so maybe the signal is at 9997 KHz and that's why I'm not hearing it.
 
So... am I understanding that this signal does exist and its purpose is to
calibrate the receiver or am I not understanding the sentence fragment that
mentions this signal? And is there something I can use on 30M?
 
FYI the K1 is my only radio so I don't have anything to calibrate it
against.
 
Craig
WB0GUU
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[Craig Rairdin]

I didn't get any responses to this question last week so I'm going to try it
one more time:

The K1 manual makes a very, very brief mention of using an internally
generated signal to calibrate the receiver. It seems to indicate this signal
is at "99.7". With an antenna disconnected I hear a carrier that is
definitely in the neighborhood of "99.7" on 40, 20, and 15M, but on 30M I
don't hear it. OTOH, I set it up with 10.1 MHz as the low end of that band
so maybe the signal is at 9997 KHz and that's why I'm not hearing it. (I do
hear a carrier around 10.170 MHz with no antenna connected.)
 
So... am I understanding that this signal does exist and its purpose is to
calibrate the receiver or am I not understanding the sentence fragment that
mentions this signal? And is there something I can use on 30M?
 
FYI the K1 is my only radio so I don't have anything to calibrate it
against.
 
Craig
WB0GUU

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[dave-281]

Craig,

After reading your note I checked my K1.  There is a signal in the vicinity of xx99.7 -
*but* when I 'CAL' to set that signal at 99.7 my freq indication is off.  It looks like
one or two things may be happening:

1) the signal should not be set at 99.7 but rather at 99.7 minus the offset you are using
(my offset is 800 Hz so I would set it to 98.9)

and/or

2) my '99.7' frequency is off to begin with and then moves away from 99.7 as I go up in
freq.  On 15m it is down to something like 98.2 (from memory, may be off).

After CALing to 99.7 minus the offset, the display is fairly close, but still off a bit.
If I cal against a better standard my displayed freq will track all of the following:

1) W1AW bulletins at 3581.5, 7047.5, 14047.5, 18097.5, and 21067.5
2) the beacons on 14100.0
3) the beacons on 21150.0
4) on 30m I can check it against WWV (I have the 150kHz option installed)

If you don't have the 150 kHz option you can still check against W1AW.  Their freq is good
to use for CALing.

Also, the signal is not really there to use for calibration - it is a birdie that happens
to fall at ~xx99.7.  I think what really happened was Wayne tweaked an oscillator
frequency to put it there - and get it out of the band.

And keep in mind that this is from a sample of one, so may be off.  Maybe someone else
will chip in with their experience.

73 de dave
ab9ca



Craig Rairdin wrote:

> I didn't get any responses to this question last week so I'm going to try it
> one more time:
>
> The K1 manual makes a very, very brief mention of using an internally
> generated signal to calibrate the receiver. It seems to indicate this signal
> is at "99.7". With an antenna disconnected I hear a carrier that is
> definitely in the neighborhood of "99.7" on 40, 20, and 15M, but on 30M I
> don't hear it. OTOH, I set it up with 10.1 MHz as the low end of that band
> so maybe the signal is at 9997 KHz and that's why I'm not hearing it. (I do
> hear a carrier around 10.170 MHz with no antenna connected.)
>  
> So... am I understanding that this signal does exist and its purpose is to
> calibrate the receiver or am I not understanding the sentence fragment that
> mentions this signal? And is there something I can use on 30M?
>  
> FYI the K1 is my only radio so I don't have anything to calibrate it
> against.
>  
> Craig
> WB0GUU

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[Mike Morrow-3]

The "calibration signal" if one can call it that, is a harmonic of the crystal oscillator for the MPU on the front panel board.  The nominal frequency of that crystal is 4000 kHz, but the circuit has been purposefully designed to actually oscillate lower in frequency.  Most I've heard of seem to oscillate around 3999.6 kHz.

Divide that by 4.0 to get a signal of about 999.9 kHz.  You'll hear harmonics, then, in the vicinity of the lower end of ham bands at:

  7 x 999.9 =   6999.3 kHz
10 x 999.9 =   9999.0 kHz
14 x 999.9 = 13998.6 kHz
21 x 999.9 = 20997.9 kHz.

The K1 receiver operates on lower sideband for all bands.  If you have properly set your CW offset to, say, 600 Hz, then your transmitter frequency will be 0.6 kHz lower than your receiver frequency.   Most hams want the frequency display to show transmitter frequency rather than receiver frequency.  In that case, when you are zero-beat with a signal at, say, 6999.3 kHz, you'd want the LCD display to show 6999.3 - 0.6 = 6998.7 kHz, which will be the frequency transmitted when key-down.

But there is no assurance that the MCU crystal in your unit is actually at the 3999.6 kHz used in this example.  There are really very few signals out there to use as a calibration signal in the narrow confines of ham HF CW bands.  The best, had you used a 150 kHz VFO span option, would be WWV at 10000 kHz.  But that would have allowed you to calibrate only the 30m band.  You'd still need known signals in the other three ham bands to properly calibrate your K1.  The suggestion to use the signals from W1AW is perhaps about as good as you'll find in the CW segments of the several ham bands, though normally I'd want another source were it available.

73,
Mike / KK5F
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[Don Wilhelm-3]

> -----Original Message-----
> ...
>
> The K1 receiver operates on lower sideband for all bands.  If you
> have properly set your CW offset to, say, 600 Hz, then your
> transmitter frequency will be 0.6 kHz lower than your receiver
> frequency.   Most hams want the frequency display to show
> transmitter frequency rather than receiver frequency.  In that
> case, when you are zero-beat with a signal at, say, 6999.3 kHz,
> you'd want the LCD display to show 6999.3 - 0.6 = 6998.7 kHz,
> which will be the frequency transmitted when key-down.
>
>
> ...

The display frequency indicated above is not quite correct.  When zero-beat
with a signal (meaning to hear the signal at the sidetone pitch), the
receiver display should indicate the frequency of the carrier.  Yes it is
true that under these conditions, the actual receiver frequency is offset by
600 Hz, but the frequency display should show 6999.3 (the center of the
receiver passband will be 6999.9 kHz)

Think of it this way - the receiver should always display the carrier
frequency that will be transmitted - and that works for both CW and SSB.

73,
Don W3FPR


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[Mike Morrow-3]

I wrote:

> The K1 receiver operates on lower sideband for all bands.  If you
> have properly set your CW offset to, say, 600 Hz, then your
> transmitter frequency will be 0.6 kHz lower than your receiver
> frequency.   Most hams want the frequency display to show
> transmitter frequency rather than receiver frequency.  In that
> case, when you are zero-beat with a signal at, say, 6999.3 kHz,
> you'd want the LCD display to show 6999.3 - 0.6 = 6998.7 kHz,
> which will be the frequency transmitted when key-down.


Don wrote:

>The display frequency indicated above is not quite correct.
>When zero-beat with a signal (meaning to hear the signal at the
>sidetone pitch), the receiver display should indicate the frequency
>of the carrier.

>Yes it is true that under these conditions, the
>actual receiver frequency is offset by 600 Hz, but the frequency
>display should show 6999.3 (the center of the receiver passband
>will be 6999.9 kHz)

Hi Don,

I agree with all you say if I want my LCD to display the **receiver** frequency,  But I think you missed my main point:  I want my LCD to display the **transmitter** frequency, since from a standoint of operating close to band lower limits, the transmitter frequency is what is subject to regulatory requirements.

So, for a LSB receiver with a CW transmitter offset, the transmitter frequency will be *below* the receiver's zero-beat frequency by the amount of offset.  For example, I use a 600 Hz offset on my K1.  If I am zero-beat with 10000 kHz WWV, my K1 display actually shows 9999.4 kHz, since that is the frequency that my K1 transmitter will emit if I key it.

>Yes it is true that under these conditions, the
>actual receiver frequency is offset by 600 Hz, but the frequency
>display should show 6999.3 (the center of the receiver passband
>will be 6999.9 kHz)

I define actual receiver frequency as the zero-beat frequency, and I define actual transmitter frequency as that which would be determined by a frequency counter.

73,
Mike / KK5F
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[Don Wilhelm-3]

Mike and all,

On a properly aligned K1 or K2, the display WILL be the frequency to be
transmitted.

Not to belabor the point (and perhaps we are really saying the same thing in
different words but not understanding each other), but when one hears a 600
Hz tone from a CW signal, the 'receiver frequency' is actually 600 Hz away
from that carrier frequency - and yes, the receiver should display the
frequency of that carrier (not offset by 600 Hz), and transmit on that
displayed frequency if all is setup correctly.

I can see this may be confusing, but the net of all of it is that the
receiver display should be [VFO - BFO - (sidetone pitch)] and the transmit
frequency is just [VFO - BFO].  The result is - if you are receiving a
6999.3 carrier and hearing it at a 600 Hz pitch, your receiver is actually
tuned to 6999.9 but the display should read 6999.3 (which is where you will
transmit if the K1 is properly aligned).

The K1 and the K2 do take the offset into consideration automatically when
computing the frequency for display (the K1 must be set for the proper
transmit offset as instructed in the manual).  It matters not whether we
call it transmit offset or receive offset, the net should still be the same.

73,

Don W3FPR

> -----Original Message-----
> Hi Don,
>
> I agree with all you say if I want my LCD to display the
> **receiver** frequency,  But I think you missed my main point:  I
> want my LCD to display the **transmitter** frequency, since from
> a standoint of operating close to band lower limits, the
> transmitter frequency is what is subject to regulatory requirements.
>
> So, for a LSB receiver with a CW transmitter offset, the
> transmitter frequency will be *below* the receiver's zero-beat
> frequency by the amount of offset.  For example, I use a 600 Hz
> offset on my K1.  If I am zero-beat with 10000 kHz WWV, my K1
> display actually shows 9999.4 kHz, since that is the frequency
> that my K1 transmitter will emit if I key it.
>
> >Yes it is true that under these conditions, the
> >actual receiver frequency is offset by 600 Hz, but the frequency
> >display should show 6999.3 (the center of the receiver passband
> >will be 6999.9 kHz)
>
> I define actual receiver frequency as the zero-beat frequency,
> and I define actual transmitter frequency as that which would be
> determined by a frequency counter.
>
> 73,
> Mike / KK5F

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[Mike Morrow-3]

Don wrote:

>On a properly aligned K1 or K2, the display WILL be
>the frequency to be transmitted.

Don,

This is not true for the K1.  The K1 operating frequency display is not as smart or foolproof as that of the K2.

In the K1, *only* the base VFO frequency (ranging from about 3.1 to 2.9 MHz from low to high end of band) is sensed.  The other oscillators that determine receiver frequency (hetrodyne crystal, product detector crystal) are *not* sensed by the MPU.  The MPU takes the sensed VFO frequency and combines it with assumed values of hetrodyne crystal frequency (based on what is has been told is the band assigned) and assumed values of product detector frequency.  Then it uses a correction factor set through the OPF function to adjust/calibrate the frequency display to make up for variences in the actual hetrodyne and product detector oscillators from unit to unit.  Likewise on transmit, the same process takes place except that the offset (transmit mixer) oscillator frequency comes into play rather than the product detector frequency.  One could smash the hetrodyne, product detector, and transmitter mixer crystals and the K1 would happily continuing displaying the same frequency as before, because the K1 MPU doesn't know that these other oscillators are now kaputt.

The K1 MPU frequency display system also doesn't know if you are transmitting or receiving.  The VFO frequency doesn't change in either case (unless RIT is on, which does alter the VFO frequency when receiving).  Thus, the K1 requires use the OPF function to calibrate the display to the transmitter frequency rather than to the receiver frequency, if that is desired.  You have to make a choice to calibrate to either the receive frequency or the transmit frequency...you can't have both.

>The K1 and the K2 do take the offset into consideration
> automatically when computing the frequency for display

The K1 design definitely does *not* do this, since the LCD frequency counter senses *only* the VFO frequency and has no idea what the offset oscillator is doing.

Somewhat related is the fact that changing the sidetone frequency on the K1 does not alter the transmitter offset.  A trimmer cap has to be adjusted to make the new offset match the sidetone frequency that was set by menu.

73,
Mike / KK5F
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