Re: LF: 136.000 spectrum

[DL4YHF@aol.com]

Hello Jim, Brian, Stewart and the group,

First of all thanks to Stewart for the excellent explanation of the stable signals on 136.00 kHz (received it too late to check the next harmonic of 8kHz but I will do that later).

I had the chance for some further investigations on 136.00X kHz on Thursday evening. Taking a closer look at one signal near 136.0 kHz, I found there where two frequencies again, about 63 millihertz apart (my 10MHz-OCXO was not on long enough, so no absolute accuracy). The separation between the two lines remained stable throughout a 30 min observation period (then it got too cold for in the shack at DF0WD). I could not find any combination of Loran lines and "harmonics" to explain this.
A small screenshot is attached. The slow drift if a result of my onheated OCXO. The frequency scale is inverted because the RX uses LSB when in "CW" position.

Question to the experts: What happens every 16 seconds (=1/63mHz)  in an ISDN net or similar ? Is the carrier phase inverted regularly for some reason ? Or what else can be the cause of the 63mHz gap, which does not seem to be related to propagation effecs ("QSB") ?

Well, not too urgent to solve this riddle; I guess we all can live with the simple fact that it is there, and -as Jim wrote- the carriers on 136.00X have been there since we started on LF.


Best regards, good hunting
 73 from Wolf DL4YHF.