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Television Standards Converters, Modulators etc Standards converters, modulators anything else for providing signals to vintage televisions.

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Old 14th Aug 2012, 5:00 pm   #1
johnlees
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Smile Band 1 TV aerial dies on me.

Mm! I thought my ancient Plustron TVR 5D (=Television Radio 5" screen Dual standard) had gone very deaf and blind on me because of a total lack of any Sporadic E on Band 1 for the past while, but then thought I'd check the aerial connections. There weren't any !

Corrosion between each dipole rod and the clamps joining then to the co-ax connection box was so bad that there was an open circuit reading and thus no electrical connection at all from the dipoles to the co-ax cable.

I demolished the lot and cleaned everything up with a wire brush in a drill, reassembled with new bolts, tested the aerial continuity to the set with a meter and it's all back to normal.

Just waiting for the Sp E now !

John.
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Old 14th Aug 2012, 5:32 pm   #2
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Default Re: Band 1 TV aerial dies on me.

Whilst there may not have been DC continuity I suspect that the stray capacitance may have been enough to still give you a connection. A simple test is whether you saw the noise level rise when you plugged the aerial into the set. At Band I frequencies the Cosmic background radio noise level should exceed the noise figure of the front end.

I think there may have been one aerial manufacturer who made a selling point of 'capacitive coupling'.

By the way: Is there any Band I analogue TV left in Europe to give you SpE?

Russia possibly??

I dismantled a Band I loft aerial when I increased the quantity of loft insulation and have not bothered yet to resurrect it because I had not received any BI SpE for a long time. I would be pleased to be told it was worth resurrecting!
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Old 14th Aug 2012, 9:03 pm   #3
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Default Re: Band 1 TV aerial dies on me.

Yes, I did think about the stray capacitance issue but with it all cleaned up there is much more background noise and interference now so I am assuming that the aerial is much improved.
According to Hybrid Tellies there are still several countries receivable.
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Old 14th Aug 2012, 9:19 pm   #4
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Default Re: Band 1 TV aerial dies on me.

At the moment there is Hungary on R1,R2, Macedonia on E4, Belaruse, Russia and Ukrain on R1, R2,R3,R4 and R5, Moldova and LIthuania also on R2. Iceland has also been seen on E4 and once on E3. So there is still some analogue Band 1 to be seen but sadly not for long and by 2014 it will all have gone. The Sporadic E openings have also dried up early this season.
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Old 15th Aug 2012, 10:38 am   #5
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Default Re: Band 1 TV aerial dies on me.

John,

Well, the proof of the pudding is the eating, so if you now get more cosmic noise and other stuff then evidently the clean-up was decidedly worthwhile.

Out of interest what is the aerial you use? Mine is a wideband 'H' based on an old Roger Bunney design from the '80s.

Simon,

Thank you for that info. I shall get the aerial back into commission, it would be nice to see something shimmering in on R1...
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Old 15th Aug 2012, 8:17 pm   #6
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Default Re: Band 1 TV aerial dies on me.

Hello, Steve. It's a homebrew wideband one which I have had for about 35 years, hence the corrosion because it's never been touched before. Heaven know where I got the design from, it was so long ago. It's got a dipole, a reflector and two directors, one only about two inches in front of the dipole.

It has been very successful over the years and I've got a log book full of various countries received. It was a good hobby, but as Hybrid Tellies says it is almost sadly no more.

John.
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Old 16th Aug 2012, 5:31 pm   #7
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Default Re: Band 1 TV aerial dies on me.

John,

The close spaced director sounds like a version of Antiference's 'TruMatch' design for a wideband dipole. In my experience it is/was a good design. My wideband H similarly has a 'Trumatch' design dipole probably like yours.

Like you, I watched DX TV over many years using a range of TVs - as you say, a sad passing.
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Old 17th Aug 2012, 9:24 pm   #8
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Default Re: Band 1 TV aerial dies on me.

Well, two periods of reception today (after weeks of nothing) on VHF Channel E2 and quite strong from the east or south-east but unfortunately unidentified.

Perhaps cleaning up all the corrosion did the trick - perhaps not. Who knows.

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Old 18th Aug 2012, 10:35 am   #9
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Default Re: Band 1 TV aerial dies on me.

John,

I forgot to ask: did you clean up the director, reflector and Trumatch resonator elements where they join the boom?

Perhaps also these elements are in two halves using 'plates' to connect the two halves together. If so they could do with a clean up as well. Otherwise if these surfaces are also DC open circuit, but still with a small capacitive coupling, they can noticably alter the performance of the aerial.

Glad to read you received some E2 DX; E2 suffers from a lot of local interference for me.
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Old 18th Aug 2012, 7:27 pm   #10
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Default Re: Band 1 TV aerial dies on me.

No, I didn't, I only cleaned the main dipole elements fixings, but now I come to think of it I think I will. I will get on to the job on Monday.

Yes, they are in two halves and fixed to the main boom with clamps using butterfly nuts/bolts so should be easier to clean than the hard to demolish main dipole clamps were.

John.
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Old 20th Aug 2012, 10:49 am   #11
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Default Re: Band 1 TV aerial dies on me.

John,

I used to clean up old aerials kindly donated by aerial riggers using Brillo Pads. Their mixture of wire wool, soap and sodium hydroxide seemed to be able to shift even the most determined coal smoke. If they are used remember to thoroughly rinse the now clean element with tap water.

Dismantling and then re-commissioning an aerial proved to be quite possible with many - but not all - makes.
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Old 20th Aug 2012, 8:51 pm   #12
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Default Re: Band 1 TV aerial dies on me.

Well, the aerial has now been totally cleaned up. Two bolts needed the junior hacksaw treatment and were replaced but most of the corrosion was easy to clean off.
This aerial has only ever been on an upside-down clothes line rotator so it's never suffered from coal smoke.

Just waiting for some signals now, though I'm not too hopeful as it's a bit late in the year.

John.
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Old 24th Aug 2012, 10:24 pm   #13
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Default Re: Band 1 TV aerial dies on me.

You can get openings late August and into September. But if you can pick up the baby alarm interference near R1 on 49Mhz and say lightning static from nearby thunderstorms,(avoid at all cost the ones that are overhead), tomorrow should be a good day, then its a good sign that your aerial is working ok.
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