Valve radio repair series starting in Practical Wireless

[SiriusHardware]

Had a brief look at the article, so may have missed it. Is there any mention of an isolation transformer when working on these "live" chassis?

That was covered in an earlier instalment of the series.

[kalee20]

Originally Posted by David Simpson

Remind me(I've only ever restored a DAC10), does the DAC90's dropper hive off 40 or 50V for a series heater chain ? And, with separate valves needing 6, 12, 20 volts VH ? Jolly confusing for a complete novice.

Hmmm... I'm struggling to see why separate valves needing different voltages in a series chain (where the currents are all equal!) is fundamentally more confusing for a complete novice than separate valves needing different currents in a parallel chain, where of course the voltages are all equal?

[David Simpson]

Just recently been repairing a Bush AC34 for someone. Series heater chain - with all B8A valves having different heater voltages. Note - that's an AC mains set. Over the years, I've worked on several makes of domestic radios, some AC & some AC/DC, which have valves fitted in series with different voltages.
To get back to the PW article(I used to buy PW for a couple of years or so in the early 60's, but changed to Practical Electronics - more interesting & challenging), perhaps a kind impartial forum member who is a regular PW reader, would keep us up to speed on the valve article series, issue by issue. Bolloxed if I'm driving round all the local rural towns trying to find a well stocked newsagent.
I'll ask for one last time - who is writing this article, and is he well regarded & experienced in VR pursuits ?? If he's just a publishing company's hack, who is grasping info off YouTube or other internet sources, then all us contributors to this thread are wasting our time.
I'm back off out to the shed to continue to work on my 5KVA S/by Genny - the good old Lister LR2 has thrown an oil leak. Much more important.

Regards, David

[stevehertz]

Personally I think that any publication that flies the flag for vintage wireless is to be applauded and welcomed. 'We' keep bemoaning how the membership is getting older, yet we always seem to err on the side of knocking any form of media that promotes it, often for reasons such as technical accuracy or it doesn't provide anything that we don't already know, and so on. Come on, see the light. We must be more open and promotional, and less fastidiously technical in our judgements of media coverage of our hobby. That, or the membership gets older and older..

[snowman_al]

Two seconds with Google gets you a link to PW's latest issue... (https://pocketmags.com/practical-wireless-magazine#)
A quick look inside gives the author as Bernard (Ben) Nock G4BXD. A long term contributor to all things valve radio. Have a look at his various web sites and museum.

[David G4EBT]

For more than twenty years PW has billed itself thus:

Quote:

'Practical Wireless is aimed at the licensed radio amateur and caters for the amateur radio hobby'.

Unquote.

Well yes - amateur radio as in 'plug 'n play' - not as it was in PW's heyday.

I don't want to sound unkind, but whereas an article about say a KW Vanguard or Trio 9R59DS etc would fit the bill, when was a Bush DAC90A, which has been done to death on forums and YouTube, ever 'amateur radio'?

But then none of us are compelled to buy PW, (which, incidentally, I bought from 1954 - 1990), even if we can find it, which mostly I can't.

There's a reason it's so hard to find. Under the 'SOR' (Sale or Return) arrangements, PW, (as with other publications), has to print and distribute the magazines, which - if not sold - are returned to the publisher for pulping. It can't afford to have magazines left on the shelves unsold. When magazines are bought by subscription, the publisher has the money in advance and knows how many magazines to print. Better still with online subscriptions as no working capital is needed to fund printing.

I'm not sure what proportion of PWs total sales is via bookstands, but I imagine it's small and declining. How much longer that can continue is anyone's guess - it's done well to last as long as it has. When Geoff Arnold started 'Radio Bygone's, it was by subscription only from the outset, which was the only sound business model on which to found a small circulation special interest magazine.

Whether or not a magazine that is so thin on editorial content is worth its £5.00 cover price will be dictated by the market.

We live in an age in which many people have 'pastimes' rather than hobbies. They dabble superficially in lots of things, but don't become involved in depth in anything. That said, some hobbies are thriving. The woodturning club of which I'm secretary had to close for two years, partly due to lockdown. We re-launched the club in March, since when we've gained ten new members, which now total 55. If it gets to 60, we'll need to create a waiting list. I dare say the same applies to model engineering.

No shortage of magazines on the bookstands, which are full of editorial.

I wish PW well in its endeavours. It's rather sad to see an 'old friend' in intensive care.

[ms660]

Originally Posted by David G4EBT

I don't want to sound unkind, but whereas an article about say a KW Vanguard or Trio 9R59DS etc would fit the bill, when was a Bush DAC90A, which has been done to death on forums and YouTube, ever 'amateur radio'?

According to this forum there's plenty of "amateurs" that have had a go with a Bush DAC90A.....

Lawrence.

[G.Castle]

Originally Posted by David Simpson

Over the years, I've worked on several makes of domestic radios, some AC & some AC/DC, which have valves fitted in series with different voltages.

Confused? Parallel heaters, same voltage, different currents, = different required heater power...
Series heaters, same current, different voltages, = different required heater power.

Please explain, are valve radios only supposed to contain valves with the same heater power? If so, I'm definitely confused

[ms660]

Originally Posted by G.Castle

Please explain, are valve radios only supposed to contain valves with the same heater power? If so, I'm definitely confused

Some can be configured for that, eg: 1.4 Volt DL** valves set for economy mode.

Lawrence.

[Dave Moll]

Originally Posted by G.Castle

Please explain, are valve radios only supposed to contain valves with the same heater power? If so, I'm definitely confused

Surely, it's not the heater power that must be the same. For parallel wiring all heaters will be presented with the same voltage, so must be rated at that voltage but can be rated at different currents to vary the heater power, whereas for series wiring the same current will pass through each heater, so it's the current rating, not the voltage, that must be the same, and the power can be varied by means of the voltage rating. No doubt, this is as clear as mud!

[G.Castle]

Originally Posted by ms660

Some can be configured for that, eg: 1.4 Volt DL** valves set for economy mode.

Lawrence.

Thanks Lawrence, good point, but what my confusion is, why would a heater chain of say, P series valves confuse anyone to find they had different voltages across them, a young friend of mine (15) had just pointed out that anyone being encoraged into dabbling in valve radios should already have understood Ohm and Kirchhoff's laws besides the dangers of live chassis and fluffy asbestos, which is a fair point I think.

[David Simpson]

Well, David revealing PW's affiliation to the Amateur Radio fraternity, has confused me. I certainly agree with Steve that any publication which encourages new interest in vintage wireless/radio is welcome. I've banged on enough in recent years about declining numbers of VR folk over 3 score years and ten, and the increasing number of "silent key" dispersals/sales. To that end, I've also banged-on about encouraging/mentoring younger folk. But, and its a big but - in a safe 21st century working environment where the "this is how we did things back in the 60's" attitude is a no-no.
I have no beef with PW, or it's article writer Ben Nock, nor am I criticizing their professionalism. However, going back to my original post - I just don't think that a DAC90 is a suitable radio for teaching valve theory or practical usage.
Thanks Al for the "Pocketmags" Google link. When I've time, I'll have a shufti at the two or three articles that have been featured so far. Then I'll re-enter the fray, if the Mods let it run.
I would also echo David's thoughts on using a good old Amateur Rx or transceiver as a article example. Not a heffing DAC90, if Ben Nock has strong connections to the amateur fraternity. Jesus, that lovely old 1950's/60's valve Coastal Radio Curlew Marine Transceiver I restored & re-crystalled to 80m years ago, would have been my choice.

Regards, David

[G.Castle]

Originally Posted by Dave Moll

Surely, it's not the heater power that must be the same. For parallel wiring all heaters will be presented with the same voltage, so must be rated at that voltage but can be rated at different currents to vary the heater power, whereas for series wiring the same current will pass through each heater, so it's the current rating, not the voltage, that must be the same, and the power can be varied by means of the voltage rating. No doubt, this is as clear as mud!

Its perfectly clear Dave! I just can't see what is supposed to be confusing about it! That's what's confusing!

[ms660]

Originally Posted by G.Castle

but what my confusion is, why would a heater chain of say, P series valves confuse anyone to find they had different voltages across them, a young friend of mine (15) had just pointed out that anyone being encoraged into dabbling in valve radios should already have understood Ohm and Kirchhoff's laws besides the dangers of live chassis and fluffy asbestos, which is a fair point I think.

Exactly, my take as well, how hard can it be, I = V/R etc.

Lawrence.

[kalee20]

Exactly - Greg's making the same point as mine (Post 42), which was triggered by Dave S's 'Jolly Confusing' remark:

Originally Posted by David Simpson

... does the DAC90's dropper hive off 40 or 50V for a series heater chain ? And, with separate valves needing 6, 12, 20 volts VH ? Jolly confusing for a complete novice.

So why is a series chain more confusing than a parallel? Is Khirchoff's voltage law harder to grasp than Khirchoff's current law? That's the confusion!

DAC90 is probably not the best radio as a first - more cramped; contains asbestos; and when finished, it still runs uncomfortably hot. But the DAC90a - ideally suited IMHO!

[ms660]

I thought from an earlier post that the PW article was about the Bush DAC90A.

Can that be confirmed for the benefit of this thread and sanity?

Lawrence.

[G.Castle]

Yes! 90A

[Station X]

Originally Posted by G.Castle

anyone being encouraged into dabbling in valve radios should already have understood Ohm and Kirchhoff's laws besides the dangers of live chassis and fluffy asbestos, which is a fair point I think

That level of knowledge is certainly not borne out by many of the threads on here started by newbies.

I think you just need to have an interest in electronics and a willingness to learn. However it seems that some newies just want to own a vintage record player or radio and have no interest in what goes on inside.

[G.Castle]

Originally Posted by Station X

That level of knowledge is certainly not borne out by many of the threads on here started by newbies.

I think you just need to have an interest in electronics and a willingness to learn. However it seems that some newies just want to own a vintage record player or radio and have no interest in what goes on inside.

I think that's a shame really. Its probably why so much interesting gear ends up getting junked.

[Radio Wrangler]

The series is being commercially published, and so the responsibility for accuracy and steering readers away from danger lies squarely on the shoulders of the publishers, PW. Likewise any kudos for good bits.

Any warnings which people on here feel need to be added will have to go in PW in order to reach the same readers as the series of articles. I assume the current editor is as happy to receive letters as Rob Mannion was.

As far as the forum goes, I think everyone must now be aware of the series. As this isn't the right place for fixing any omissions or bad choices in the articles, and we're starting to get stuck in a well-exercised loop, it seems that everything worth saying here has been said.

We'll just have to see how the rest of the articles go.

David