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Murphy V310A
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August 12, 2017
8:57 pm
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Chris
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marc said
[…] Aurora as they do put out a rather strong signal which some sets do not like.
   

That’s putting it mildly, with Andrews set being designed as a “fringe” set, it will positively have kittens with an unattenuated signal. It will be like its sitting on top of the transmitter.

August 12, 2017
9:05 pm
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PYE625
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The output from my Domino converter is high and I use an 18db attenuator with it. I also have a variable one like Marc’s, so will have to experiment a bit.

It’s been tricky enough just getting used to spelling  Awora,  erm  Aurura….no…..  Aurora !!

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Andrew.                                                                                   

                         

August 12, 2017
9:17 pm
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marc
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PYE625 said
The output from my Domino converter is high and I use an 18db attenuator with it. I also have a variable one like Marc’s, so will have to experiment a bit.

It’s been tricky enough just getting used to spelling Awora, erm  Aurura….no…..  Aurora !!

So it wasn’t just me then with the Awora, erm  Aurura….no…..  Aurora ! laugh

My Aurora is fitted to a distribution system feeding some 32 outlets (4 X 8way splitter/amps) and I’ve found that by having the variable attenuator set at roughly at 2 o’clock position virtually all my sets seem happy with the signal but occasionally when the odd set is unhappy it’s so simple to tweak the variable attenuator than to start plug swapping with the fixed ones.   
 

August 12, 2017
9:20 pm
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nuvistor
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Belling Lee, I think it was , produced fixed attenuators similar to that one. Absolutely essential in this area when receiving BBC1 on Ch 12 and ITA on Ch 9. Ch 12 was a lot weaker signal than Ch 9, there are some accounts of this not being the case but from experience it was so. See the Pembers pondering Archive.

https://www.radios-tv.co.uk/Pembers/405-Lines/tx-list.html#BBC

 

Usually a 12db attenuator was required to stop the cross mod, I.e, ITA Ch 9 floating in the background of BBC Ch 12. There was a variable one with coax connectors, more chubby than the fixed on but inline, you had to find the best compromise between too weak Ch 12 and cross mod.

Talking to the guys working in the big rental outfits they were told to adjust the preset AGC but that did not stop the cross mod but reduce it, the rental company wouldn’t supply the attenuators.

Frank

August 13, 2017
2:08 pm
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PYE625
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Hey, everyone with an Aurora north of Peterborough set their’s to CH11, all south of Peterborough set to CH3 and I’ll see if I can pick anyone up……

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Need a few more I think, only getting ignition interference from a motorcycle grin_gif

Andrew.                                                                                   

                         

August 13, 2017
3:13 pm
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nuvistor
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Ignition interference  is a good sign, the signal stages must have some life in them.

Frank

August 13, 2017
5:13 pm
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Till Eulenspiegel
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Now I must make a start on that Murphy V410.  

Here’s pictures of it.    It’s not one of the best examples of the species.

Till Eulenspiegel.

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August 13, 2017
5:58 pm
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Jayceebee
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If I remember rightly the V410 had a party trick, on a good strong signal if you advanced the contrast to maximum the picture would go completely negative but still remained perfectly synchronised. Always wanted to see what happened on the opening titles of Danger Man, the first few seconds were negative so the V410 should of course have turned it positive.

John.

August 13, 2017
9:02 pm
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PYE625
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This afternoon I spent a little time re-stuffing capacitors in the boost HT line. The symptom on screen was reducing width and brightness along with low and slowly falling boost HT volts. C136 was getting rather warm and had developed a runny nose, so the two beefy wax capacitors C133 top right, C136 lower right in picture below received attention. Afterwards, boost HT was better at around 425v (it should be 475v), but the HT is slightly low at 190v instead of 205v.

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Andrew.                                                                                   

                         

August 13, 2017
9:07 pm
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PYE625
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Till Eulenspiegel said
Now I must make a start on that Murphy V410.  

  

Hi Till, 

Yes please…. It will be very interesting indeed  thumb_gif

Andrew.                                                                                   

                         

August 13, 2017
9:27 pm
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PYE625
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After re-stuffing the boost HT capacitors (first and second pic), I thought it wise to replace the line drive coupling capacitor C129, plus C127 (a crumbling Hunts mouldseal) in the line hold circuit, both roughly in the centre of my last picture. I used “Suntan”  capacitors and they kind of look a similar shade to the brown Hunts Mouldseal type.

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Andrew.                                                                                   

                         

August 14, 2017
11:14 am
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Cathovisor
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PYE625 said
 I used “Suntan”  capacitors and they kind of look a similar shade to the brown Hunts Mouldseal type.
  

Is that a brand or a slang expression, Andrew?

To know yet to think that one does not know is best; not to know yet to think that one knows will lead to difficulty. Lao Tzu
August 14, 2017
11:46 am
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nuvistor
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August 14, 2017
12:41 pm
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PYE625
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Hi Mike, yes that is a brand name and Frank has identified them. I find them reliable, and reasonably priced from places such as ebay, and they fit in reasonably well with equipment made in the late 50’s and 60’s.

Andrew.                                                                                   

                         

August 15, 2017
7:08 pm
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PYE625
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Hi all,

A courier called today and delivered a small box. Within this box was a very small black box aka as an Aurora standards converter. I had to find a 9v PSU as it doesn’t come with one.

Anyway, I managed to find a PSU and connect the Aurora up to the Murphy with my 18db attenuator. Set the converter to CH3 and after some tuning adjustment to the set, achieved pretty much perfect sound and vision of TCC.

I did the same for CH11, but the gain of the set is reduced slightly at this frequency, but hardly a problem.

Some manipulation of presets was required of course, linearity, height, width etc, but the results were rather surprising to say the least……

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Andrew.                                                                                   

                         

August 15, 2017
7:42 pm
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nuvistor
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That’s a good, no great,  picture, is it the camera or are the highest frequency grating visible, they look like they do.

There is some shading at the top that could be the camera shutter and is there some foldover on the left.

Well done again, excellent job.

Frank

August 15, 2017
8:03 pm
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marc
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Hi Andrew,

Welcome to the Aurora club ! smile

And doesn’t that V310’s picture look a treat thumb_gif

Marc. 

August 15, 2017
8:32 pm
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Great results. You’ll wonder how you ever managed without an Aurora..an excellent example of how modern technology complements old. Can you imagine building an Aurora with valves or even all transistors…?

August 15, 2017
8:44 pm
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PYE625
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Thanks guy’s,

But I have done nothing really…. the Murphy is a ‘flippin good set. The top frequency grating is visible, and the camera causes dark bands across the screen (shutter speed I guess).

The Aurora is quite an amazing device indeed, and although expensive, is something you can’t really do without. No more faffing about with DVD players, instead an instant test card on 405 lines on any channel from a 9v battery and a matchbox !!

Andrew.                                                                                   

                         

August 15, 2017
9:07 pm
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Katie_Bush
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Hi Andrew,

So you finally got one then! – Keep the input voltage to 7.5V and that Aurora will last a lifetime. That’s Daryl Hock’s advice by the way. Above that and you’re into excess energy dissipation, below that and your into weird device artefacts. That said, the Aurora can cope with a fair range of voltage supplies, but Daryl himself says it was designed around an optimum of 7.5V. A useful adaptation is to screw on an ‘F’ connector to Belling Lee coax adaptor (available via eBay and similar places). That will then not only give you the convenience of a BL connection, but also acts as a very good heat sink to keep the unit that much cooler, plus, if someone accidentally bumbles into the coax cable it just yanks out the plug, rather than damage the Aurora.

Anyway, that puts you into a club of just over 600 users, I believe in the UK, at the last count.

Marion

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PYE625

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