----- Original Message -----
Sent: Sunday, June 20, 2010 8:46 PM
Subject: Re: LF: Re: 137.500 kHz ROS beacon
''''for instance the French stn F5WK cannot hear you'''''
Well , yes , that's the point of it all , no noise, no trace just 100% pure digital data rolling over the land , like the un-seen fog of progress
IARU - R-1 plan .. 137.4 to 137.6 digital modes , with the note that CW is 'not allowed'
I think the test and the frequency went fully to 'to plan' and paves the way for a magnitudinal increase in data use on 137 , to date limited by bandwidth to psk31 , ros-mf by design occupying on 50% of the allowable space on 137 and 99% of the 100Hz allocations for 500K. and passing via a non linear system , how long will it before the first live data qso over the pond ?
G .
Sent: Sunday, June 20, 2010 6:30 PM
Subject: Re: LF: Re: 137.500 kHz ROS beacon
Gary
There are too many variables with these experiments for instance the French stn F5WK cannot hear you but you are S5 solid on 137.5 here at my qth
The RX stations antennas need to be analyised otherwise it misrepresents what you are doing.
Can u pse use frequencies below 136.5 kcs otherwise there is a problem with EU and Russian stations using the area 137 - 137.778 kcs for QRS acty.
also this is the DX window area for the USA and others.
73 de mal/g3kev
----- Original Message -----
Sent: Sunday, June 20, 2010 4:31 PM
Subject: Re: LF: Re: 137.500 kHz ROS beacon
Hi Mal,
Thank you for your report & comments. The mail you replied to gives all the details of equipment in use for the test beacon.
I would like to be able to have a QSO using morse but I have to admit to a complete loss of confidence as I have not used the mode for 25 years which was one year after I passed the test in 1984. Looking back, letting it go was a silly thing to do.
I do enjoy testing out these "weak signal" modes & in the report I received from Michel F5WK last night he wrote that he could not hear the signal or even see it on SpecLab but he got a complete decode. So as a weak signal communication mode it works.
Just to elaborate on the antenna, it is a 12 metre base loaded vertical with a small elevated inductor of 500uH at about 9 metres & a 1 x 3 metre capacity top with a 120uH spiral inductor. In my small garden I have no space to go outwards only upwards.
73,
Gary - G4WGT.
On 20 June 2010 13:48, mal hamilton
<[email protected]> wrote:
Gary
If that was you last nite on 137.5 kcs you were strong enough for cw or qrs3 no need to struggle with decodes from elswhere.
also I had a qso with G3XIZ this morning on 137.0 kcs and got 599, he was 569.
Not sure what antenna u were using but it was putting out a fair signal to this qth. Your radiators are probably acting as an antenna above earth.
de mal/g3kev
----- Original Message -----
Sent: Sunday, June 20, 2010 12:07 PM
Subject: LF: 137.500 kHz ROS beacon
Having successfully bench & on-air tested a x2 harmonic amplifier method of driving my G0MRF Class D LF transmitter, I ran a beacon last night (Saturday 19th) on 137.500 kHz.
An extract from my previous e-mail description is shown at the end.
Using the equipment & method described below, the ERP from my 12 metre vertical antenna was around 150mW. The mode was ROS MF-1, 100 Hz bandwidth.
I received the following report from Michel, F5WK in JN18HP, a distance of 410 miles (661 kilometres) in daylight.
>> Not even a faint trace on a QRSS3 spectrum but:
>> RX1: 19:23 @ 5.9 Hz: 9 <STOP> -37 dB
>> RX1: 19:28 @ 5.4 Hz: O4WGT <STOP> -34 dB
>> RX1: 19:33 @ 5.4 Hz: G4WGT <STOP> -31 dB
The x2 harmonic low level amplifier is a simple way of driving a Class D type of transmitter which employs a divide by 2 drive chain. My limitation with multi tone drive is that my DDS VFO will only produce 2 frequencies ie. the main frequency & a CW/Rx offset which has previously limited me to 2 tones as with RTTY & DFCW modes.
Please bear in mind that it will not be suitable for modes like PSK were tones are transmitted simultaneously.
At the moment the 2 small PCB's are precariously lying on the desk, when I have cased them I will publish the circuit & pictures.
73
Gary - G4WGT.
***********************************************
After a few days experimenting & bench testing a method of driving my
G0MRF Class D Tx on the 137.000 kHz band from my linear transverter I finally
constructed a harmonic amplifier producing a 274.000 kHz signal from 137.000
kHz input. An "on-air" trial was conducted resulting in a QSO with
Graham G0NBD on 137.000 kHz using ROS data mode software.
My thanks to Graham for his ideas & tests.
The mode used was ROS MF-7. The equipment used for the QSO was as
follows. Kenwood TS-440 to my LF-MF linear transverter producing the
137.000 kHz signal, followed by a tuned harmonic circuit & buffer
amplifier whose output was 274.000 kHz therefore at x2 drive for the Class
D Tx. The x2 signal is then divided by the Tx driver chain in the
normal way to provide 137.000 kHz to the PA.
This method should also work well using WSPR & other similar modes.
*********************************************
