RAN Technology

Phasing SSB transmitter alignment - the easy way!


Technical 0 Comments 07/20/2019 

thanks to ZL2AMJ

Posted By: Robert Nickels (ranickels)

Equipment manuals and handbooks of the 1950s and 60s 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!

Click on the image title or on the image itself to open the full-sized image in a separate window.

  

A first-person history by an Airway Keeper's daughter

Life on the (Radio) Range at Medicine Bow WY in the 1930s
Category: Vintage Radio
 Most vintage radio enthusiasts are aware of how intertwined the development of radio and aviation were.   Many still enjoy using low frequency receivers and DX-ing the "beacon band" which was a key element of the first generation of aviation radio and navigation.   Before there were radio beacons, pilots depended on visual beacons - the flashing (rotating) light...  READ MORE
- Robert Nickels (ranickels),  12/31/2019 
  

Remembering Michael Hopkins, AB5L (SK) - a unique individual

Founder and humble scribe for the Five Meter Liberation Army!
Category: Vintage Ham Radio
Michael Hopkins AB5L is fondly remembered by early denizens of the internet and specifically the "Boatanchors at the Porch" mail reflector.   A truly unique individual, Michael made the internet a happier place through his eclectic interests (ranging from Tecraft converters to ferrets) and his wonderful imagination and storytelling ability.  Through his writing, we le...  READ MORE
- Robert Nickels (ranickels),  12/23/2019 
    This all started when I discovered a fantastic collection of vintage photo QSL cards on a Google+ site – I’d encourage every ham to spend some time looking through this amazing bit of history:   https://plus.google.com/115747543308902188110The photos capture a wide range of ham gear and stations from the spark era through the 70’s, and nearly every picture trigger...  READ MORE
- Robert Nickels (ranickels),  12/11/2019 
   I have no interest or affiliation with the company and discovered this product when I was looking for a good degreaser to clean my jukebox.   IT IS THE BEST!I like data, so I put confidence in the test results that can be viewed in the infographic below.I also like RESULTS and this stuff delivers.   Greasy dirt and grime are instantly dissolved and wipe away.   You ca...  READ MORE
- Robert Nickels (ranickels),  12/09/2019 
   Some pieces of vintage ham gear are not really unique, but are so rare as to almost never be seen.   The Multi Elmac PS-500 power supply is an example, it was sold as an AC power supply for the A54 and A54H transmitters in the mid-50s. There's nothing special about it - just a big transformer with 5 volt rectifier, 6.3 volt filament, and 500 volt secondaries.  Two nice chok...  READ MORE
- Robert Nickels (ranickels),  11/14/2019 
  

My experience with the Nouveau 75

a new AM QRP transceiver from the 4SQRP group
Category: Technical
Mini-review of the Nouveau 75 by W9RANI like it, warts and all!OK, maybe not quite that "mini"...here's a few of my impressions of this innovative kit from the 4 State QRP Group.I've been interested in amplitude modulation of a class E PA for some time and after Dave Cripe said to stay tuned for the next 4SQRP offering, I wasn't too surprised to see what it was, and bought on...  READ MORE
- Robert Nickels (ranickels),  11/12/2019 
   International Crystal Company of Oklahoma City was certainly best known for its crystals but the company was also a not-insignificant player in the CB radio manufacturing business, and also had a pretty extensive line of experimenter kits.   The kits typically had one to three tubes on a PC board and provided a single function, such as an RF amplifier, or transmitter, although some were ...  READ MORE
- Robert Nickels (ranickels),  08/02/2019 
    Finding myself in need of a tool to remove a bad bearing on a blower from a linear amplifier I first tried the usual automotive type gear puller but it wasn't able to get underneath this small 5/8" OD bearing.   So I improvised a tool that took 10 minutes to make, cost a few cents, and had the job done in no time at allThe secret is wedges sold at the home improvement stor...  READ MORE
- Robert Nickels (ranickels),  07/16/2019 
  

W9RAN Field Radio

Vintage light aircraft radios repurposed
Category: Technical
In the early days of aviation radio, transmissions originated from the ground using the longwave transmitter also used for homing,  and pilots acknowledged by wagging their wings.  It didn't take long to realize the benefits of having transmitting capability onboard the plane as well, and the first generation of aircraft radio used the low HF band.    Given today's...  READ MORE
- Robert Nickels (ranickels),  05/11/2019 

VIEW News Item

Making A Transistor Radio

in memory of Rev. George Dobbs G3RJV (SK)
VIEW News Item

Take the Boatanchor Survey!

Let authors and organizers know what you're interested in
VIEW News Item

W9RAN's "VERSA-TR" (as featured in Dec. 2018 QST)

A Versatile T/R solution for SDRs and vintage radios
VIEW News Item

MICROPHONIA! is here

Cool mics from my collection and ones I wish were
VIEW News Item

WBBM-AM tower moves to Bloomington IL

watch the old tower fall (video link below)

(There are currently no Blogs.)