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.

   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 
   Watch the video  trailer for the 2019 monster movie that relies on a 1950s vintage Hammarlund SP-600 and Collins 30L-1 amplifier....  READ MORE
- Robert Nickels (ranickels),  04/20/2019 
   I find the show-biz association of the founder of Allied Radio, Simon Wexler, to be rather fascinating.  What started out as a supplier of crystal set parts led to a family that became a major force in the entertainment industry and in Chicago business...including many recognizable names:"Allied Radio (now known as Allied Electronics) is a company with a long history. On August 6, 1...  READ MORE
- Robert Nickels (ranickels),  04/14/2019 

Hazard E. Reeves - audio pioneer and defense contractor

Making crystals in midtown Manhattan during WWII
Category: Historic
 Hazard E. Reeves (1906-1986) may not be a household name, but his work is well known to every moviegoer.   He was an American pioneer in sound and sound electronics, and introduced stereophonic sound for motion pictures. He met Fred Waller at the 1939 World's Fair and saw the potential of Waller's "Vitarama" system which he invested in and which soon became the mo...  READ MORE
- BRADLEY STONE (NB9M),  04/12/2019 
    In his book "In Touch with Leo", the success and growing backlog of CB-100 orders is what drove Leo to his banker, Lou Ross, who asked him why he didn't anticipate the number of orders and required capital.  Leo responded "Lou, never on God's green earth could I have believed such an influx of orders!".    More funding was needed than the bank ...  READ MORE
- Robert Nickels (ranickels),  03/18/2019 

(There are currently no Blogs.)