Re: [Elecraft_K3] K3 frequency delta from receive to transmit


Mel Farrer <farrerfolks@...>
 

I want thank all of the suggestions.  However, my question was more centered on if there is a design issue that could allow a delta to exist in T/R carrier frequency, regardless how you measure it. 

Mel, K6KBE



From: "Carl Moreschi n4py3@... [Elecraft_K3]"
To: Elecraft_K3@...
Sent: Tuesday, December 16, 2014 4:27 AM
Subject: Re: [Elecraft_K3] K3 frequency delta from receive to transmit

Another way to zero beat with only one radio is to keep switching
between USB and LSB.  When the pitch if the signal does not change, you
are exactly on frequency.

Carl Moreschi N4PY
58 Hogwood Rd
Louisburg, NC 27549
www.n4py.com

On 12/15/2014 11:03 PM, 'Fred Townsend' fptownsend@...
[Elecraft_K3] wrote:
> Yes you can easily zero beat as Matt suggests. I agree with you Dale that
> method can be problematic. I suspect accuracy below 10HZ is a matter of luck
> rather than science. However accuracy can be vastly improved by adding a
> null detector such as a meter or scope. There is still the question of how
> accurate WWV is when it arrives at your QTH but I will leave that discussion
> for others.
>
> I can remember in some engineering class the prof proclaimed the virtues of
> Lissajous Patterns on an oscilloscope for comparing frequencies. It works
> fine if the frequencies are harmonics or less than 20 Hz. At 20 MHz it’s a
> crock. There is a U-tube piece if you want to look it up. The problem with
> most methods it is hard to tell if the error beat is above or below the
> frequency of interest.
>
> In the lab I discovered a simple method that is versatile and tells you if
> you are high or low. It requires a triggered oscilloscope and a couple of
> probes. Put one probe on the weaker signal and connect to the vertical
> channel and adjust the view for optimum . Connect the other probe to the
> external trigger input. Be sure to set the sweep to external trigger. Then
> adjust the sweep frequency to show a few sinewaves. The sinewave will appear
> to move either left or right. Adjust your frequency until the sinewave is
> stopped. Now you are as good as your reference frequency.
>
> 73
> Fred, AE6QL
>
> From: Elecraft_K3@... [mailto:Elecraft_K3@...]
> Sent: Monday, December 15, 2014 6:23 PM
> To: Elecraft_K3@...
> Subject: Re: [Elecraft_K3] K3 frequency delta from receive to transmit
>
>
> Hi Fred,
>
> It's not perfect accuracy for sure, but it will get within 10 kHz, which is
> good enough. I've used the method for years without any problems with being
> on freq, including some fussy MARS nets. I've found trying to zero beat the
> carrier can be more problematic to try and hear the zero beat plus I find it
> no more accurate than using the side tones which are much easier to hear
> providing one has a second rx.
>
> Dale, k9vuj
>
> On 15, Dec 2014, at 19:38, 'Fred Townsend' fptownsend@...
> [Elecraft_K3] <Elecraft_K3@...> wrote:
>
> Please see comments below:
>
> -----Original Message-----
> From: Elecraft_K3@... [mailto:Elecraft_K3@...]
> Sent: Monday, December 15, 2014 4:52 PM
> To: Elecraft_K3@...
> Subject: Re: [Elecraft_K3] K3 frequency delta from receive to transmit
>
>  > I like to do it this way.
>
>  > Set your K3 on SSB. Set a second receiver on AM (NOT SSB). Set your K3 on
> the highest WWV transmission frequency that you hear WWV. Set the AM
>  > receiver on any WWV frequency it hears. Tune for the beat note. We are
> not listening to the carrier frequency now, but listening to the 600 hz side
> tone
>
> Dale this brings to mind a question. Do we know the 600 HZ tone is phase
> locked to the carrier? If not, it seems accuracy would be lost.
>
> 73, Fred, AE6QL
> GL
> Dale, K9VUJ
>
> On 15, Dec 2014, at 17:36, farrerfolks@... [Elecraft_K3]
> <Elecraft_K3@...> wrote:
>
> I have always thought that if I set the receive signal zero beat on WWV and
> see less than 2 Hz error would be reflected in the same possible offset on
> any band. I was told that on 40 meters, my carrier on SSB was 20 Hz low.
> Is this possible, and if so why??? Thanks.
>
> Mel, K6KBE
>
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> ------------------------------------
> Posted by: "Fred Townsend" <fptownsend@...>



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