VK Logger Ham Radio Forum Archive

Good Morning Gents

I have just erected a 6DBd Vertical on 6Metres that seems to work very well. I am wiping out a TV on UHF nearby. My TV is much closer ie: about 6metres from the antenna and not receiving any interference but the TV receiving the interference is about 20metres away. There is no preamp on the TV getting the interference and is receiving digital TV. It has a Panasonic DVR which is inline between the antenna and TV. I am thinking I made need to build/buy a High Pass filter. Any recommendations?

Thanks in advance, the forums are the first place I go when I need some ideas.

Cheers

Tony, (not telling you how to suck eggs...but...) have you tried taking the DVR out of the line and changing the leads being used?

You need to find out why?
Overload
IF
Faulty TV antenna, lead, coax, balun.
All sounds bit suss.
Does the dvr have a VHF IF?
From my experience even with EME 1KW and 10KW erp u don't wipe out UHF TV rom 50MHZ unless there is problem.
Never fitted trap to anyones TV around here.
Which channels on the TV all or just one or two?
Ask VK3AXH he was an RI.
Check your setup also

2 c

VK4BZ wrote:Tony, (not telling you how to suck eggs...but...) have you tried taking the DVR out of the line and changing the leads being used?

No I haven't changed the leads but taking it out of line is not an option as I will have a war on my hands It has RF in via a F socket on the wall and then into the DVR. There is a 3 RCA lead into the TV Video/audio inputs. I bet connecting the TV direct will probably fix the problem. I just found two redundant coaxes leading from a tower into the roof cavity near where the new antenna is located. I have cut them and will retest.

Cheers

VK3ZAZ wrote:You need to find out why?
Overload
IF
Faulty TV antenna, lead, coax, balun.
All sounds bit suss.
Does the dvr have a VHF IF?
From my experience even with EME 1KW and 10KW erp u don't wipe out UHF TV rom 50MHZ unless there is problem.
Never fitted trap to anyones TV around here.
Which channels on the TV all or just one or two?
Ask VK3AXH he was an RI.
Check your setup also

2 c

Hi Steve

Thanks for the thought provoking comments. TV antenna is fairly new ie: 6 months old. Video output to TV from DVR. Not sure if it also has a VHF output I am pretty sure it is UHF but I will check. It effects all UHF channels, so it must be front end overload. I will check if there is a high/low signal setting on the DVR ie: a internal preamp but i doubt it. OK will do some more checking and also rewire my MFJ voice keyer so I can TX on test whilst I check the other tv. Unfortunately the IC-7600 doesnt have the facility of TXing over and over.

Cheers

Hi Tony

There was a nice little 3 stage high pass filter on the UKSMG web which I built which works well with little attenuation.

Ross

Whilst it "might" be a problem with your gear I think the odds are in favor of the problem being at your neighbors house. I understand discussing these issues with someone who can't watch the box can be difficult and I'm sure none of us need to tell you how to suck eggs.

Without knowing the whole story or your relationship with your neighbor I offer the following;

I would argue that a TV system that fails on UHF with a nearby 6m transmission has a problem.
You can already demonstrate that there is no problem at your house, it must be his problem.
Whilst your neighbor won't let you remove the DVR and other equipment you need to do some troubleshooting.
If your neighbor won't let you troubleshoot I would direct them to the KingRay FL3BPMH Filter.
I wouldn't fit it myself as "I'm not a qualified TV installer" and would direct the neighbor to the local TV guy.

Hi Tony,
Lou's suggestion of the KingRay filter is I feel on the money, I have them in use here on the feed to the TV (before the mast head amp). I am in a fringe area and find that the main effect is that the TV/DVR RF front ends just go into blocking mode (overload) and that a good filter in many cases is the answer.

The nice thing about the KingRay filter is:
* its commercially made, you can show them the box and pamphlet so they know its not some back yarders lash-up
* water resistant
* has F connectors already
* It works well

As any one can buy them, If all else fails you can recommend they have one fitted and give them the details of it so its not up to you to do the work.

I did a small page on my personal web site about these and will readily recommend them to any one who will listen
http://www.users.on.net/~pedroj/tvi/index.html

It has great nulls on all of the VHF and HF ham bands.

Steve's fault finding list is a great place to start, eliminate the easy stuff in the house, leads etc and bypass the DVR to see if it alone is the culprit (have a Panasonic DMR 880 here that is quite good with high levels of RF).

Regards

All excellent advice , don't accept that you have an obligation to touch the system , the kingray should help when they have it fitted , last time I got a visit (some time ago) the inspector went next door and made suggestion as to what they needed to do including filters etc as I had no fault and he mentioned the poor quality of the offending device in thier home , good luck with it .

Gday Tony.

" I am wiping out a TV on UHF nearby"

I will just translate that for you:

"A neighbours TV is experiencing reception difficulties due to the substandard receiving apparatus on his premises."


ACMA would most likely easily detect this "substandard receiving apparatus" if it comes to the crunch...


cheers vk6six

VK6SIX wrote:Gday Tony.

" I am wiping out a TV on UHF nearby"

I will just translate that for you:

"A neighbours TV is experiencing reception difficulties due to the substandard receiving apparatus on his premises."


ACMA would most likely easily detect this "substandard receiving apparatus" if it comes to the crunch...


cheers vk6six

Problem is, and I should have mentioned it earlier, I am living temporarily at my Octogenarian parents place and its their DVR that I bought for them a year ago as a gift. See the political issue I have just been advised by a mate he had the same problem with a number of TV's and DVR's at his place and he has a spare High Pass filter board the same that he says has fixed this issues with those TV's with DVR's on 6Metres. I am off tomorrow to pick it up and then I will swing back via Jaycar to buy a cheap and nasty Aluminum box to house it in. Stay tuned as I will advise how it all goes. Thanks to everyone it has all been very helpful.

Cheers

AH!

Well that's a really big omission.

You need to pull out all the stops on this one. It does no good to have your parents upset with you.

Good luck.

Ah...ageing live-in parents syndrome.

Yes, can pose some issues.

Kid gloves and tap-dancing shoes are required for this venture!

Or you could try these.....

http://www.uksmg.org/content/filter.htm
http://www.uksmg.org/content/braidfilter.htm

Made several of these up in the early 1990's and housed in a small diecast box..... worked a treat on our UHF output VCR (but nothing could help the neighbors who at that stage persisted with VHF Ch0 VCRs )

VK4BZ wrote:Ah...ageing live-in parents syndrome.

Yes, can pose some issues.

Kid gloves and tap-dancing shoes are required for this venture!

You got it

Cheers

Problem solved. Fitted a high pass filter built by a mate inserted it inline with the antenna and Voila! I still need to mount it in a shielded metal box but it doesn't receive any interference when i run 100watts. It will be interesting to see how it goes with 400watts on 6Metres

This is the beast: http://www.uksmg.org/content/braidfilter.htm

Thanks for all the input

Cheers

Oh by the way the DVR affected was a Panasonic DMR-XW385

Cheers

In stumbling through some service notes it appears the analogue tuner front end is basically a set of barn doors so good the filter cleans that problem , well done , now the newer units don't run analogue the problem wont occour again ?

The interference was to digital TV signals as there is no Analogue here

Cheers

on some machines the tuners run all the time and without termination r power down you get problems , ok ?