TVI Causing disruption with the station manager

Discussion in 'Interference Problems' started by Craig M6YIT, Mar 13, 2018.

  1. Craig M6YIT

    Craig M6YIT New Member

    Hi,
    As I'm sure 99.999% will have gathered ( especially from the call) I'm a relatively new licensee, I have enjoyed several months of " cutting my teeth" locally by using 2m,( I feel 2m is great to learn about local operators and gain knowledge about correct protocol, and operating procedures etc, " many amateurs have been operating for many years and it's a good mark of respect to operate totally correctly") but I have now saved up and got an HF set. This is where the trouble begins ... I have set-up a temp antenna to use until I set up my proper longwire, the temp consists of a purchased 9:1 situated at nearly the end of the garden fence ( approximately 5ft agl) with an active sloping up to the facia board ( about 25ft up) and a random counterpoise running along the floor at approximately 90 degrees to the active ( counterpoise approx 7m long ) no gnd rod at present, but this is interfering with our TV ( which doesn't bode well with the station manager etc) however no neighbor has complained. My SWR is below 1.5:1 across most HF bands and my active length is 16.16m ( one of the typically "sweet" lengths), would the addition of an earth rod remedy the problem or should I look at choking the TV coax ( i.e. wind it round a ferrite in a similar pattern to a balun) or is the only option basically more sepperation between the wire and TV?
  2. Ken G3SDW

    Ken G3SDW Moderator

    Hi Craig, thanks for posting on the RSGB forum.

    From what you have told me then everything you are doing is 100% OK, coincidentally i use here the same antenna set up and have no problem at all.

    You do not say what HF bands are causing your problem but more important in your situation is the TV set up.

    Were is the TV antenna?, how many sets run off of it,? if there are more than one set then how is the signal distributed?

    The reason why i am asking this is that in most cases such as yours it is the TV installation more that the amateur set up.

    Come back to me and we will work through and get your problem sorted.
  3. Craig M6YIT

    Craig M6YIT New Member

    Hi Ken,
    I think I might have sussed the bulk of the problem.

    It was me who installed the TV antenna, and when I have thought about it further I think it's due to the proximity of the coaxial cable.

    I installed the TV antenna on the chimney stack, using a standard lashing kit ( ant = Blake dmx 8 ), but when I have thought about it further I ran the coax down the roof-tiles to the guttering and facia then down the wall to approx 1 foot agl where I formed a 3 turn loop and then a pinned drip loop, before it going through the wall to and isolated TV outlet, from there it goes into my black-gold TV tuner card in my media center pc then via the passthrough to the ant inlet of the TV.

    But ( DOH!!!!! Moment) the final end of the active of the longwire terminates about 3-4 feet from the TV coaxial download, so I think the best bet will be to setup the proper longwire asap, but with atleast about 10-15 feet sepperation. Then take it from there, but deffo ground the antenna aswell. I think this should resolve a lot but I will keep people posted with progress and description of setups etc, so hopefully I can help others at the same time.
  4. Ken G3SDW

    Ken G3SDW Moderator

    I don't like to disappoint but I don't think you are going in the right direction but give it a go and see what happens.

    My set up is the same and my feeder is closer than yours and much closer to my last head amp and running 100w and no problem at all.

    50 years in TV and have been down this road many many times.

    Let me know how you get on.

    73
    Ken
    G3SDW
  5. Ken G3SDW

    Ken G3SDW Moderator

    Right Craig, sent the last post very first thing this morning, been out and now returned after thinking about your problem.

    Before you do anything else prove to your self where the problem is getting in by connecting first of all your TV antenna direct to your TV, ie take out your Black-Gold TV tuner and do a test.

    If it is not there then you know what the problem is,many add on`s have poor rejection of local RF.

    If the problem is still there when the external tuner is out of the set up then make sure that, and that of course is you have some, disconnect any HDMI cables as they can be a source of RF getting into the TV,many HDMI cables have no screening only an earth return wire.

    With only the TV antenna connected and the problem is still there then look again at the radio antenna set up but i am confident that it will not be that as long as it is all functioning OK.

    What radio do you use for HF?

    At the end of the day as you are newly licence`d then with 10 watts there should not be any breakthrough at all only incompatibility to local RF/

    My antenna feeder runs along side my TV antenna feeder down the side of my bungalow and using the same antenna set up as you, virtually identical, then with ten times the power have not problem what so ever, once we know were the RF is getting in we can take the appropriate action.

    So check everything out and you will find out what it is, let us know how you get on, always here to help at any time at all
  6. Craig M6YIT

    Craig M6YIT New Member

    Cheers ken, nice to hear some reassurance ( and I take it vaguely from the reply, that you have been a TV aerial installer( unless I'm reading it wrong)) but anyway, due to the weather I haven't touched the installation yet so everything is still as described initially, my potting has went off now and everything is good to go for putting up the proper antenna now but I feel it would be a good exercise in emc analysis to do some testing of the existing setup before things get changed.
    But as the new / proper antenna will be totally independent of this temporary setup, I reckon leaving the setup in place aswell would be do-able ( it ain't eatin no meat ), so in the interests of analysis and experimentation I am going to leave it in place ( unless I need to move it for the new one), but I am going to try tbe various aspects of isolation and see what results I get ( hopefully my findings may help others in similar settings), quite interesting that your feeder is ran parallel with your TVs coax and you experience no breakthrough ( I wonder if your TV coax is just standard pme grounded?), anyway I going to run through various testing and post what I find ( and try to be as complete and concise as possible)
  7. Ken G3SDW

    Ken G3SDW Moderator

    No not an installer of antennas but Audio Visual repair and service, over 50 years man and boy.

    The antenna that you have is a very good one and will serve you well, not sure what antenna you hope to install later on, one comment on the dimensions of the inverted "L" that you have now but it is a bit short of what it should be, but of course this will not make any difference to your problem.

    To understand the correct dimension of a non resonant long wire then take a read of this link i ma sending you here.

    http://www.hamuniverse.com/randomwireantennalengths.html

    No the feeder i use is bulk standard RG58 of good quality and is not grounded at all and its length is approx` 26m, most of the way at ground level and once it reaches the bungalow runs at 0.5m above the ground.

    From all your details so far then off the top of my head i feel that your Black Gold tuner card, everything else in the equation should not be the culprit as long as there is not a fault on the TV, the make and model you have not said so far.

    Finally what HF radio are you using, you did not say in your last email.
  8. G3YMC

    G3YMC Member

    You shouldn't be getting many TVI issues with the 10W of the Foundation Licence. It would help though to know which bands you are using, TVI problems are often worse on the higher HF bands, especially 10m. But in our current propagation conditions you probably aren't doing much on that band...
    73 Dave G3YMC
  9. Craig M6YIT

    Craig M6YIT New Member

    I am in the process of putting up the "proper" aerial and should get that completed soon, but in the meantime I have disconnected the Black gold tuner card and wound the TV downlead a few time's around a miscellaneous torroid (one from a batch which I haven't tested the bandwidth of yet) and that seems to have resolved thing's for the time being, but time will tell once the new aerial goes up and I dare to then move above 5W and go to my full legal 10W.

    So in short it appears initially that the Blackgold TV Tuner card mustn't have very good EMC characteristic's / immunity, at a later date I will investigate further with regard to the tuner card, i.e. it may be possible to improve it's shielding, and then still use it (which bode's well with a skin-flint like me), but atleast for the time being I am fine to use the set on low power (5W). I cannot for the life of me remember exactly which model of blackgold tuner card it is, but when I find out I shall post it.
  10. Ken G3SDW

    Ken G3SDW Moderator

    Hi Craig, after thinking hard about your problem i came down to this Black gold card you have mentioned.

    It obviously has little or no RF immunity, hence putting a ferrite on the antenna input proves a point, its always best to use the correct grade of ferrite for this purpose, as any old ferrite will not do so take a look at this site http://www.ifwtech.co.uk/g3sek/in-prac/index.htm#big31 and try to understand about ferrites and there applications.

    I have tried to contact Black-Gold but none of there contact details are working so feel that they are no longer in business, but at the end of the day and as Dave G3YMC said earlier with 10w then you should not have a probelm with a basic TV installation, pointing back to your Black-Gold tuner

    Finally as i have asked you a couple of times before what HF rig are you using?? and does it have an internal tuner??
  11. Ken G3SDW

    Ken G3SDW Moderator

    Hi Craig, have not heard from your for a while so wondering how you are getting on, all good i hope?

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