some things changed …
Monthly Archives: October 2013
Impressions from CQ-WW-SSB
During the weekend i made a few 10m QSO in the CQ-WW-SSB contest. In the evening i took the following screenshots of 20/40/80m.
KBS from Sofia in DRM/AM Simulcast
The korean national service KBS is currently testing DRM-AM simulcast. This means the same service is transmitted side by side on co channels. One channel contains the service broadcasted in DRM mode, the next channel contains the same service via AM. This gives the opportunity for some nice comparisons between DRM and AM stability and audio quality. Find two audio snippeds below.
The transmissions will be every evening from 19UTC to 20UTC on 5875kHz (DRM) and 5885kHz (AM) – source www.drm.org
The screenshot shows a part of the radio band yesterday evening. Unfortunately the conditions to Sofia had been really poor. You can see the both signals of KBS and some much stronger signals from other broadcasters.
Obviously the DRM signal was suffering from sideband lobes falling into the DRM spectrum limiting the SNR because at the end when the modulation was already switched off the DRM SNR increased rapidly.
Voice audio snipped – first DRM, then switching to AM
Music audio snipped – first DRM, then switching to AM
The DRM audio was transmitted in AAC+ Mono with 18kBit/s. It gives a rather nice sound compared to other DRM broadcasts that can be received at the moment.
DUR activity 2013 October
After 2 month of inactivity from my side another trial with 3 bands. I had 23/13/9cm with my 1.5m dish.
Meanwhile i integrated the 5W PA for 9cm. This time Murphy tried to do its very best.
I had to tear down the antenna 3 times in between. First i had troubles to find the correct lengths of the ropes for the mast.
When testing the transverters i experienced 9cm was not switching to TX. During my mast trouble i accidently disconnected the 9cm power cable at the mast unit.
After that operation was going relatively smooth. This time i was heard very well by the others on 9cm. But i experienced that my RX seems to be really poor. I always gave much better reports than i got. I did not check the sensitivity so far. Everything you dont check will not work ;)
In the end i had 17 QSO on 23cm, 9 QSO on 13cm, 5 QSO on 9cm.
ODX on 23cm was HA5UA/p. Thanks for the patience during that weak signal QSO.
Next steps with improving my setup will be a new rotator control. The original KR600 controler has some issues and i somethimes do not get correct heading. 23cm would need to be mounted to the mast. Unfortunately i dont think that i can get the mast up then. It would be too heavy.