[Central-Electronics] question on 100V VFO project

[K6JEK]

No, you don't need to shift the frequency by mode   As you stated,  
the math that translates from the VFO frequency to the transmit  
frequency is different for different bands but it's the same for all  
the modes on any given band.

Jon, K6JEK

On Jan 18, 2009, at 6:10 PM, <eugene at hertzmail.com>  
<eugene at hertzmail.com> wrote:

> I have no idea what happened to that email. I spent 15 minutes writing
> and editing that thing and when I hit send, who knows what happened.
> Looked empty in the sent box too. So let's try again.
>
> My DDS VFO project will have a frequency display using nixies. In  
> order
> for the frequency display to show the proper number, the user (me)  
> will
> have to input the selected band. So I will try to have a band switch
> like the one on the 100V. User selects, say 20M, I know the mixing
> arrangement and offset the displayed frequency accordingly. Simple
> enough.
>
> My question has to do with emission mode.  Does my VFO need to be told
> what mode in use in order to properly display the frequency?
>
> For example. I set the transmitter to 14.000 MHz CW. The VFO is now at
> 5.5MHz (or thereabouts).  The frequency display should ready 14.000.
>
> Now, if I set my emissions mode to LSB and call up a friend with a
> modern digital readout rig and tell him "meet me on 14.000 LSB" and I
> don't change the VFO frequency, will we be good to communicate?
> Likewise, if after 10 minute ragchew I say, "now meet me on 14.000  
> USB"
> will we again be able to communicate without me changing my VFO?   
> (yes,
> I know the conventions on using USB and LSB on the bands, this is just
> hypothetical).
>
> Or, should my frequency display change up/down a little based on my
> mode?
> Put another way, if I change from LSB to USB on 14.000, should I  
> need to
> adjust my VFO frequency such that the friend with the digital rig can
> understand me properly? Now, I don't mean tweak it, I mean change  
> it by
> some real, predictable number like +/- 2.8 kHz or something?
>
> Does this question make sense? (I hope so! It's the second time I've
> written it!)
>
> Thanks
> Eugene
>
>
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