[minima] Re: Minima BFO Question
- From: "Wayne McFee" <nb6m@xxxxxxx>
- To: <minima@xxxxxxxxxxxxx>
- Date: Fri, 14 Mar 2014 09:50:49 -0700
Hi Eldon,
Take a look at Mark, G0MGX’s blog, at
g0mgx.blogspot.co.uk
specifically at his post in January, 2014, labeled “Minima Carrier Adjustment”,
most of your questions about the BFO will be answered.
Basically, for lower sideband, the BFO frequency is set at the upper edge of
the filter’s passband, and for upper sideband the BFO’s frequency is set at the
lower edge of the filter’s passband.
Because of the Minima’s LO mixing scheme, which will invert the sidebands due
to the LO being higher than the IF, you actually do the reverse of the above
when setting the BFO frequencies in that XCVR.
But take a look at Mark’s spectrum analyzer screenshots and you will see
clearly how it works.
73,
Wayne NB6M
From: Eldon Brown
Sent: Friday, March 14, 2014 8:53 AM
To: minima@xxxxxxxxxxxxx
Subject: [minima] Minima BFO Question
(Sorry if this is a repost)
I have finished constructing the Farhan Minima Transceiver BFO Oscillator
Module for my Transceiver Experiments.
See: http://wa0uwh.blogspot.com/search/label/Minima
And now I have several questions:
1. What should the actual BFO Frequencies be for generating USB and LSB with a
20MHz IF?
2. Or at least, What is the expected difference between the two Frequencies?
3, Does this all depend on the width of the Crystal Filter?
4. In normal Transceiver operations, does the VFO Frequency also have to
change (a little) when selecting the opposite Sideband?
Any help would be appreciated, Thanks.
Regards,
73 - Eldon - WA0UWH
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