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Dear Group,
i want to share with the group some informations on
EbNaut recently exchanged between me and Tom, DK1IS. He hold in
his shack some marine radios that are almost ready for this mode.
Domenico, IZ7SLZ wrote:
Noted your excellent setup in qrz.com.
So maybe you are familiar with marine radios.
Mine is composed by a Sailor exciter s1301L and a Standard Radio
reserve transmitter ST86A used as PA (120W).
Receiver is a JRC nrd-92m.
Both equipment synthetizers are steered with an
external homemade 10 MHz GPDO.
This setup is working fine also on LF and i use it in EbNaut
experiments.
Since you can control your Hagenuk tx and rx with a Rb oscillator,
may i invite you in some EbNaut test or qso?
Tom, DK1IS wrote:
Mine is composed by a Sailor exciter s1301L and a
Standard Radio reserve transmitter ST86A used as PA (120W).
Receiver is a JRC nrd-92m.
Nice radios in either case - I just downloaded the specs. Ah, the
S1301L is the MF extended version: fine! But like with my EX1001 the
smallest tuning step is 100 Hz - this was the reason for me to let
the exciter work on 13.6 MHz resp. 4.76 MHz and divide the output
frequency down by 100 resp. by 10. Btw, from Sailor I use their fb
fiber core rubber antenna insulators, 60 cm long and very robust,
for ships - they stand the 8.9 kV rms LF voltage on my Marconi since
15 years in every weather. I bought them for peanuts at a marine
radio shop during holidays on Bornholm island, Denmark.
Both equipment synthetizers are steered with an
external homemade 10 MHz GPDO.
This setup is working fine also on LF and i use it in EbNaut
experiments.
Since you can control your Hagenuk tx and rx with a Rb
oscillator, may i invite you in some EbNaut test or qso?
Originally the EX1001 has no external reference input but a rather
good central TCXO at 9 MHz. I added a PCB with 10 MHz input from
the rubidium oscillator, dividing down to 1 MHz and then filtering
out the 9 MHz harmonic with two CB xtals. Works fb and can be
switched over to the primary TCXO.
EbNaut: thanks for the invitation, Domenico, but so far no
experiences - being not the real PC freak up to now I avoided time
and effort to get in process. May be the appetite will come later
...
Domenico, IZ7SLZ wrote:
Just for your information (and hoping to let you hungry :-)) i
briefly describe my EbNaut arrangements:
First of all, S1301L Exciter synthetizer has been modified with a 10
MHz OCXO instead of its original TXCO. I added a simple PLL that
controls the voltage of the "frequ. adj." pin of this OCXO by
comparing the 10 kHz reference signal (coming from the GPS) and 10
kHz from the divider.
Yes, S1301L has only 100 Hz resolution. I studied its circuit
diagram and noted that it is not very difficul to obtain at least 10
Hz resolution by adding another loop in the synthetizer. But i never
performed such modifications. This becouse i'm using a PCI slot
sound card with good specifications that, after Spectrum Lab
calibration process (using 1pps signal from the same GPS), gives an
output audio very precise and almost without glitches.
The audio card is a PHASE 88 PCI from Terrasoniq (German design).
So i use this audio to modulate the exciter in USB mode and i can
obtain the precision and resolution needed (on milliHz).
Ok, this is not the best arrangement to obtain TX signals; Markus
and Wolf never suggested it. But, thanks to Spectrum Lab great job,
it works, as confirmed by many EbNaut decodes and OP32 measurements
using DF6NM grabber.
To obtain EbNaut bpsk modulation i just feed the exciter with a tone
(around 1500 Hz - depends on final QRG) generated by Spectrum Lab
via a ring modulator composed by 2 audio transformers and 4 diodes.
Ring modulator is switched by the two RS232 signals ( DTR - RTS)
managed by EbNaut-tx program.
In Receiving side, i have modified the JRC NRD-92M to accept a 10
MHz TTL signal from the Sailor synthetizer (after small buffering).
So receiver is now calibrated enough for EbNaut. Rx audio goes to
Spectrum Lab that performs some filtering, NB and gives a .wav file
prepeared for EbNaut-rx decode program.
The time synchronization is also vital for EbNaut. I'm using a small
software (written by me) that decodes GPS telegrams and according
the 1pps signal, sets the PC time periodically.
GPS in use is a Rockwell Jupiter (coming from an out-of-order
vintage AIS DEBEG3400).
Tom, DK1IS wrote:
Thanks for the most interesting infos - to become QRV in EbNaut
seems to be less than complicated I thought . Nice idea to overcome
the 100-Hz-steps of your exciter by modulating it with a suitable
audio frequency which is necessary for EbNaut anyway! I could do it
with my EX1001, being also a SSB/CW/RTTY-exciter, too and could even
avoid the frequency deviders with it - nice approach. But due to the
filter passband and the modulation one hasn´t a direct frequency
readout on the exciter any longer - shouldn´t be a real problem.
Before going this way I would have to check the phase characteristic
of the EX1001 audio/modulation path; in a pinch I could use your
ring modulator technique too.
Btw, for my GPS controlled units I also use the Rockwell Jupiter
10-kHz-output. Up to now the 1pps pulse only drives a LED - if its
flashes coincide with the ticks of my mechanical but
DCF77-controlled alarm clock, I can be sure that the Jupiter has
synchronized - archaic, isn´t it ?
So, a lot to think about. Perhaps one fine day we will meet in
EbNaut ...
73 all, Domenico iz7slz
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