I don't recall the exact explanation, but it has something to do with 
the way single sideband was originally generated.

That original circuit, for whatever reason, shifted to upper sideband 
above 40 meters.

Many transceivers did not give you the selectable sideband option as 
late as the mid 60s. The National NCX3, Swan 240, and I think the Swan 
350 were like that.

The original Heath HW12 series was too. The A model added the 
selectable sideband option.

Speaking of the HW-A series, I acquired an HW32A 20 meter model from 
the estate of a friend. For who knows what reason, it has two lower 
sideband crystals in it. I have the crystal for upper sideband, but 
haven't changed it out yet.

K5XU

----- Original Message ----- 
From: "Phil Scovell" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 13, 2010 11:19 PM
Subject: Upper and Lower side band


I think I heard once but I can't remember so does anyone know why the 
=
various bands are used for upper and lower side band?  Just curious. 
=
There's got to be a reason why it is different based upon the band you 
=
are using.

Phil.
K0NX


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