[Boatanchors] SSB Generation - Phasing VS Filter Opinion Sought

[Robert Nickels]

On 7/19/2019 5:19 PM, D C _Mac_ Macdonald wrote:
> My 1st SSB rig was the W2EWL rig but I never knew how to align it to get rid of unwanted sideband.  Only had a cheap VOM!

Equipment manuals and handbooks were filled with complex oscilloscope 
screens and discussion of ripple and as a result proper alignment of a 
phasing rig eluded most hams.    But a clever New Zealand ham, Fred 
Johnson ZL2AMJ was able to see what everyone else had missed, and 
published a short note in the NZ ham magazine in 1972 that makes the 
process simple and requires only a sine wave audio generator and a 
simple output detector:

The principle is simple.  We all know that feeding a single audio tone 
into a properly aligned SSB transmitter will produce an unmodulated 
carrier output (this is how most filter rigs produce CW).   This is the 
desired outcome.

An improperly aligned phasing rig will have both carrier and opposite 
sideband imbalance.   If we inject a 1 kHz audio tone and the carrier is 
not balanced, the result will be AM - a carrier with a sideband 
separated by 1 kHz on either side.   The output detector that is 
attached to the transmitter is nothing more than a crystal radio or 
field strength meter that will demodulate this signal to allow a 1 kHz 
tone to be heard in the headphones (or amplified speaker as I prefer), 
no different than an AM transmitter will do.    Step one is to adjust 
the carrier null controls to elminate the 1 kHz tone.    This takes less 
time than it does to type this sentence!

With the carrier nulled there will now only be a  2kHz tone audible.   
This is the result of the desired sideband beating against the undesired 
sideband, which are 2 Khz apart with a 1 kHz tone.    Now the Audio and 
RF phasing controls can be adjusted to null the 2 kHz tone.   Switching 
between USB and LSB is necessary to reach the best compromise.

Thats's  it!   Two simple nulling adjustments, no oscilloscope or even a 
VOM needed.      And if you don't trust your hearing or wish to have a 
visual indication, just download one of the free audio spectrum analyzer 
apps for your smartphone or PC and it will display the  1 and 2 kHz 
signal peaks in real time.

ZL2AMJ is  known by many as the inventor of the "Tucker Tin Two",  a 
minimalist SSB transmitter using just two tubes, and was a leader in NZ 
amateur licensing for many years.   He became a Silent Key in 2015 but 
in a previous email exchange I asked him how he came up with this clever 
method that no one else ever had suggested.  His reply was "it just 
seemed obvious to me".   And so it is!

Fred's original description can be found here: http://tinyurl.com/y2qjgehr

73, Bob W9RAN

PS:   A simple $50 rtl-sdr will also serve as a "poor man's spectrum 
analyzer" to allow direct viewing of HF signals and is a must for any 
workbench.