[ARC5] Measuring sideband suppression. (Was BC-458 based SSB rig)

[Robert Nickels]

On 11/16/2013 8:47 PM, Leslie Smith wrote:
>   Fred described an arrangement to   suppress the unwanted sideband
I've used that method with great success, and consider it a brilliant 
idea.  In fact, it's the fastest and best way to align a phasing rig and 
I don't bother hooking up a scope anymore.

Below is an OCR of the text of the article.   The schematic that 
accompanied it in an RSGB book where I found it shows basically a field 
strength meter -- a capacitor coupling to the RF output of the 
transmitter, a diode detector, and a pair of headphones.   I built a 
little fixture with this circuit with an RCA connector that feeds a shop 
audio amplifier, instead of phones.   I'll be happy to send the scan to 
anyone who would like the original.

I later came across a US-made clone of the Tucker Tin Two and had a nice 
exchange of email with Fred, who is pleased (and somewhat surprised) 
that anyone still knows about these things anymore. He's been very 
active in creating instructional materials for new hams in NZ.

73, Bob W9RAN

Aligning Phasing-type 5.5.8. Exciter!

In Break-In. May, 1972, Fred Johnson. ZL2AMJ, describes
a simple but effective method of aligning phasing~type s.s.b.
exciters. " Receivers, oscilloscopes,  spectrum analyzers, and
other test gear are not needed; the method is inexpensive,
accurate and quick," he writes. In fact, apart from a pair of
high impedance phones, a resistor and two capacitors, the
only requirement is the (built-in) 1 kc/s tone generator and a
dummy aerial. The various pre-set controls can be set up
while listening to audible beat notes in the phones with the
objective the elimination of the notes while maintaining output.

To appreciate the operation it is necessary to think of the spectrum
produced by a.m. and s.s.b. transmitters modulated
by a l kc/s note, with the set-up shown in Fig. 77. With a
fully-modulated a.m. signal there will be the carrier and the
two equally spaced beat notes. and one will hear the l kc/s
beat between the sidebands and the carrier.  But if the carrier
is removed, we hear instead the beat between the two side-
bands spaced 2 kc/s apart, so one hears a 2 kc/s beat. Now
if one of these sidebands can be removed without re-introducing
carrier, there will be no heat note.

So we have an arrangement which tells us whether the
carrier is present (1 kc/s tone),  unwanted sideband (2 kc/s
tone) with the loudness of these tones providing an indication
of the amplitude of the unwanted signal component(s).

Thus the exciter can be aligned by achieving maximum
output on the meter (M) while eliminating the beat notes in
the phones -- this will then show that we have maximum
sideband output without a carrier or a second (unwanted)
sideband.