DXING WITH THE FTDX3000 - PART 1

DXING WITH THE FTDX3000 - PART 1

In my last post, I noted reception of the Alaskan station KNLS, broadcasting on a number of different frequencies with their recently repaired transmitter and antenna system. One frequency that appears to give the station some trouble is 9920 kHz at sign on 1300 UTC for their Mandarin service. Unfortunately, FEBC in Manila is also in operation at the same time on that frequency (from 1230 UTC). Both stations are being heard at Mount Evelyn at equal strength! In addition, a jamming station intended to disrupt the KNLS transmission starts up at the same time with a continuous siren sound!

 It all sounds quite messy!

 Some shortwave listeners may not be familiar with using single sideband for receiving stations transmitting in the Amplitude Modulation (AM) mode. I have prepared a little video designed to demonstrate reception of SWBC signals in single sideband (SSB) mode. Under certain circumstances, this can be beneficial in providing better reception and more pleasurable listening in times of heavy interference (QRM). In this example, the KNLS / FEBC / Siren Jammer clash outlined above has been recorded. Switching to SSB helps make monitoring a little easier.

 Perhaps some of our less experienced DXers and SWLs may find this video of interest. I welcome any comments, which can be left below or at the YouTube site.

 This video is the first in a short series featuring my new Yaesu FTDX3000 transceiver. You'll get a good idea of what this rig can do by seeing it actually in operation on the shortwave bands. There are more videos to follow.....

 73 and have a great weekend everyone!

 Rob Wagner VK3BVW


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Comments

  1. AnonymousJune 15, 2015 at 8:29 PM

    Hi Rob,

    I regularly view your report and very much enjoy the information you provide.

    Thanks for your observations about the frequency collisions and jamming interference on 9920.

    I am currently the Frequency Manager for FEBC International and have been aware of the jamming of our Vietnamese transmissions for many years - not only is 9920 currently affected between 1200 and 1330 Z, but also 9795 from 1100 to 1200 Z.

    There are multiple jamming transmitters in Vietnam located, we believe in both the North and South of the country running about 10 kW. They are typically set a few hundred Hz off our carrier frequency and are frequency modulated to give the siren effect. If only one jamming transmitter is active, the use of upper or lower sideband is an effective way of minimising their effect. However, sometimes they are located on both sides of the carrier.

    The effect on wideband portable AM shortwave receivers is quite pronounced.

    We have shifted our Vietnamese broadcast frequencies over the years, only to find that the jamming transmitters eventually locate us and shift too!

    We persevere, despite the jamming, because of skip zone effects within the country which provide some localised relief.

    KNLS broadcast primarily to North West China and we cause minimal mutual interference to each other in our desired target zones - I believe that KLNS are not significantly affected by the jamming. Our target area is the whole of Vietnam.

    Kind regards,

    Graham Baker VK8GB

    ReplyDelete
  2. Rob WagnerJune 16, 2015 at 8:46 PM

    Hi Graham,

    Thank you for your informative comment and the description of the jamming methods used by the Vietnamese! Most interesting!

    I was not aware that the jammer was for FEBC. When I tuned in a few minutes before the KNLS s/on, FEBC was loud and clear, and without the jammer. Then as soon as KNLS signed on, the jammer appeared, so I assumed (apparently incorrectly) that this was for the Alaskan station.

    Were you advised that KNLS would be using this frequency for their service at that time? It seems a pity that there has to be a clash at all between the two stations (even if, as you say, it's minimal), especially when there are other available frequencies that are vacant.

    Thank you for your kind comments about the MEDXR blog. Much appreciated. And thanks again for your valuable information surrounding the jammer.

    All the best, Graham,

    Rob VK3BVW

    ReplyDelete
    Replies
    1. AnonymousJune 17, 2015 at 9:14 AM

      Hi Rob,

      Yes we were aware that KNLS was going to use 9920. I spoke to Kevin Chambers about the collision and the jamming we experience, at an HFCC meeting sometime ago. He arranged to move to another frequency for the A season that year but it seems to have slipped through the cracks this season. Kevin has been a bit busy with the start up of their Madagascar station. Frequency management for US based shortwave stations is handled by the FCC.

      Unfortunately there are not enough frequencies available worldwide to have clear channels at all times. Part of the work of HFCC is to minimise mutual interference (apart from finding clear frequencies) - there is a standard applied that requires 17 dB protection in the designated target areas using the field strength expected for 90% of the time from the wanted signal against the signal level expected only 50% of the time from the unwanted broadcast. The main "busyness" at HFCC is working through collision lists produced each day of the conference and negotiating frequency use with other broadcasters face to face.

      Regards,

      Graham

      Delete
    2. Rob WagnerJune 18, 2015 at 9:22 PM

      Graham, thanks for taking the time to provide this interesting explanation. Much appreciated. Rob

      Delete
    3. UnknownJuly 2, 2015 at 6:41 AM

      Congratulations

      Delete

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