Re: [softrock40] KX3 and Si570 tuneing step noise
- On 10/12/12 15:27, Alan wrote:
----- Original Message -----
Subject: Re: [softrock40] KX3 and Si570 tuneing step noise
> between two and one years ago the Freeze-M bit is added to the
> documentation, it is not sure (for me) if there was a new chip or it was
> available but never documented. Need to do some testing to find it out,
> never done it.
> It was the same time Silabs did make the 7ppm chip version, so I expect it
> was added to the existing chip.
Yes, that is what Sid says and my tests confirm. Or do they?
So you need a chip that is not older then
> say one year to be sure. (Don't know the store time at Tony).
> I don't think the Freeze-M bit will remove the hick-up of the receiver,
> for changing freq. (at TX (fsk) it is mandatory!), it can make the time a
> little smaller, maybe.
Reading the data sheet it seems to me that they say the switch is very quick but not absolutely smooth.
Maybe that is enough?
I suppose I am opening a Subject that Sid has been through before. I did not read all the stuff he pasted in. But does Freeze M
apply to large frequency changes?
No, just small changes. I have never thought small changes were a problem. Maybe this only shows when SDRs are properly configured
to use low-noise "sound" systems like the Widget?
This still seems to apply to large changes. And the 10mS?
"Note that changing the DCO frequency
outside of the ±3500ppm window will cause the output
to momentarily stop and restart at any arbitrary point in
a clock cycle. Devices sensitive to glitches or runt
pulses may have to be reset once reconfiguration is
But this does not confirm what Kelvin reported, no obvious jumps.
I'm still confused.
> At the block schema the mixing of the KX3 looks like the softrock, even
> with the 2m osc signal from the si570. I expect there is no detail internal
> schema available. When using the I&Q outputs on a PC with HDSDR it
> maybe easier to see on the screen.
So it is! But the pictures do not actually show a Softrock inside:)
I was interested to see the assembly instructions. Experience with a screwdriver essential!
73 Alan G4ZFQ
With the SDR-Widget it was horrible enough to mask audio when tuning with the rotary encoder, same on the SR v6.3 when used with the K5BCQ si570 Controller but back then I thought it was just noise generated by the rotary encoder.
73 ... Sid.
-- Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support Senior Staff Specialist, Cricket Coach Microsoft Windows Free Zone - Linux used for all Computing Tasks
----- Original Message -----
Subject: [softrock40] Re: KX3 and Si570 tuneing step noise
> I have built some three standalone SI570 based oscillators and they all suffer from tuning noise, as you claim.
> I have built another one who claimS to have eliminated this noise, but I have not tested it yet. He claims to have adjusted the
> Freeze M DCO:
Please let us know when you have tested this.
And may I remind anyone with a recent Softrock with a Si570 manufactured since the beginning of 2011 that an AVR USB controller with
V 15.15 firmware has the Freeze_M feature. The AVR would need replacing because Tony still uses V 15.12. Fred would be very
interested if this could be tested.
73 Alan G4ZFQ
>> Yes that's what got me thinking, looking at the block diagram of the KX3
>> Hi Fred,
>> which can be downloaded at the address below
>> http://www.elecraft.com/manual/KX3%20Manual%20Block%20Diagram.pdf is
>> It looks almost like a softrock rx from the front end filters to the
>> opamp before the DSP,
>> I have searched for the schematic but no luck so far. If anyone has a
>> KX3 can you please
>> verify that on large tuning steps there is no chuffing . hickups ?
>> > I don't think the Freeze-M bit will remove the hick-up of the
>> > for changing freq. (at TX (fsk) it is mandatory!), it can make the
>> time a
>> > little smaller, maybe.
>> > At the block schema the mixing of the KX3 looks like the softrock,
>> > with the 2m osc signal from the si570. I expect there is no detail
>> > schema available. When using the I&Q outputs on a PC with HDSDR it
>> > maybe easier to see on the screen.