The AM Forum

After being QRT for most of the current year due to issues with the antenna, SAQ plans to make a transmission on November 16:

https://us1.campaign-archive.com/?s=x&u=521e9c51318e4c7f70e1e6b56&id=faa0cd10da

Note that there appears to be a typographical error in the posted schedule, it appears that the tuneup and transmission of VVVs de SAQ will commence at 1530 UTC, or 1030 EST on the 16th.  There may be some
some preliminary testing on air on Tuesday the 15th, which will be announced on short notice on the Alexanderson Society web site.  A livestream from the transmitter site on YouTube will start at 1525 UTC on the 16th.  Watching the video on the livestream is useful to know when the RF actually is being put into the antenna. 

Even though the transmission will be during daylight over most of the path to the US, it still should be copyable at a low background noise location.  I copied a similar daytime transmission in October of 2020 using only a 75 meter Hamstick and my Wandell and Goltermann selective level meter at the Barn Island boat launch parking lot about a mile from my home QTH.  That location is about a quarter mile away from any power lines and has a very low noise floor at VLF frequencies.  I will most likely listen from there on the 16th, using a short (nominal) 200 foot Beverage antenna.

Livestream is up on YouTube.

Copied entire transmission, Q5 at about -95 dBm through static crashes.

Chris, when you say -95dBm, what’s your reference? Or, how low is that level? And I don’t mean a milliwatt on 600 ohms, exactly….

I’m an audio guy by trade, 40 years worth. That level, as an audio signal, could be fed into an average mic preamp and then an audio amp and speaker and be heard, about 10-15dB above the noise floor. Is the signal that strong, that I could wind a loop antenna and connect it to a PA system and be done?

Ed

I’m using a selective level meter originally used in measuring channel signal levels on old school
microwave and coaxial cable frequency division multiplex long distance circuits.  The meter is basically a quad conversion superheterodyne receiver with a wide range analog S meter that  is calibrated in dBm.  What if is displaying the signal level presented at the input port with specific input impedance, typically 75 ohms.  So, essentially a tuneable calibrated AC voltmeter.  It includes a pair of IF filters 1700 Hz and 400 Hz and a product detector selectable for either USB or LSB, and also provides analog audio output, so it also
functions as a receiver, although it’s totally lacking in AGC function. To keep things in perspective, an S9
meter reading is generally considered to represent a nominal -70ish dBm signal level.  At -95 dBm, the SAQ signal assuming 6 dB per S unit, would translate to about an S5.

Picture of the Wandell & Goltermann AT-611 at Barn Island:

To answer your question re hearing the signal with a loop antenna (or any antenna) plugged into an audio amplifier, you would need a detector specifically either a regenerative receiver or a TRF receiver or a superhet
with a BFO to beat against the CW signal put out by SAQ.  The SAQ alternator when it was new in the late teens and early twenties of the 20th century, was received by very simple receivers usually regenerative ones, with ether no or few stages of amplification at RF other than that of the detector stage.  In the modern day, VLF signals are observable and can be heard by connecting antennas into the analog inputs of computer sound cards, and using spectral processing applications or SDR software processing.

The SAQ Alexanderson alternator VLF transmitter was the first practical means of generating a nawwowband discrete CW signal at a high power level, the next step beyond the high power broadband spark
and arc transmitters.  The SAQ machine is the last operating one of its kind.