Just catching up with my March issue of Silicon Chip. The regular Vintage Radio section discusses restoration of a Tela-Verta model 204C clock radio.

The author (a Melbourne-based academic) describes how he was advised by a "rather rustic member of the HRSA" to wash the chassis "rather aggressively" and leave if for a month or so to dry ... so he did wash it aggressively, power transformer and all.

It should come as no surprise to anybody -- other than apparently the author -- to learn that when he powered it straight up 5 days later the transformer soon emitted smoke.

SC's editor helpfully chimes in at that point to say that it's not a good idea to wash power transformers (LOL!), and to do a HT insulation check on old transformers before powering them up.

Some credit is due to the author for telling the story against himself, but this sort of electrical ignorance is not the what I expect to find in the Vintage Radio section.

There was a discussion recently on the SC Vintage Radio section at our Radio Club meeting. There have been some very serious errors getting through. I was critical of the 6A8 / 6J8 discrepancy between circuit and drawing. 6J8 & 6A8 are not the same. The Pentagrid 6A8 was superseded by 6J8 as a SW tube; It has a Triode exciter directly coupled to a Heptode. The drawing said 6J8 but had the Pentagrid drawn. OK it was a factory stuffup, but it should have been noted.

The two tubes will interchange without damage as the Triode grid lines up with the 6A8 oscillator grid. This does not seem to be understood, so you may see more on that, as I have written again with the Clubs & my concerns.

In 40+ years, I have found 6A8's, 6J8's, 6K8 & ECH35's, can't recall an X61M: All being the wrong valve in a set. Some servicemen used anything that would make a set go:albeit not well.

The 6J8 / 6A8 substitution in an Astor JJ & others will compress the bands & it ends up picking up aircraft NDB's at the low end.

If you are not happy with the way that the column is going, do write to the editor.I do not like writing to an editor without referencing to a valid area of concern & qualifying why I am concerned. editorsiliconchip.com.au

Several Club members and I do not like seeing inaccuracies, like the circuit of the Tela-Verta not exactly matching the set featured as there was a switching circuit missing and a vacant hole in the cabinet & no satisfactory reference to why, & doing anything about it.

I also do not think that there is an adequate understanding of paper caps & their leakage. These can impinge seriously on the grid bias, most of the valves do not like positive on the grid & it can lead to damage. If a coupling cap is below 50Meg resistance (and most wax papers are) it is finished (Lafayette). There is also an issue uprating input caps on the filters:

There is a limit to a rectifier valves filter capacity & that also applies to different voltages on the same valve. eg 80/5Y3 at its maximum plate volts will be a choke input filter. Too big strips the cathode. This does not seem to be understood, which is of concern.

One must also be careful of modern caps & resistors. Modern caps rarely have surge volts listed and many filament rectifiers & diodes can get close to twice EMF before the heaters get to cause conduction in the valve.

Marc

The 6J8G drawn as a 6A8G wasn't just a one off. Checking various original Stromberg Carlson manufacturers service manuals shows that this oversight had remained unchecked for a considerable amount of time.

The Tela-Verta 204C circuit diagram as featured in SC was drawn by the AORSM so it's accuracy cannot be confirmed. And note the 6A8G - it's drawn as a 6J8G!

Marcc. The vacant hole in the Tela-Verta was for the alarm/sleep control of the original clock. Since the original clock was unservicable, a modern clock movement was installed in its place.

For a couple of years now I think SC's vintage radio column has lacked a bit of purpose and it has drifted away from its original educational aspect to one just showcasing various models. I always look forward to reading it each month but there is room for improvement. I think I will write soon as well, with the following suggestions:-

1. Steer back to one regular contributor. At the moment everyone seems to be having a go.
2. At least half of the articles each year should be a tutorial on some aspect of vintage electronics theory or covering practical restoration techniques: receiver alignment, rewinding coils and transformers, fault finding, and most importantly - how to stay alive when working on the various types of radio chassis. Such articles are a good reminder to those who are experienced but more invaluable to those starting out. This knowledge is not being passed on adequately enough in my opinion.
3. Articles should be written well enough in advance so that information of a factual nature can be verified before publication.

A general point made at the meeting was that of accuracy. It is not unusual to see blatant mistakes in the odd circuit & there is one on the American forum http://antiqueradios.com/forums/viewtopic.php?f=6&t=272490 where the set had no B- as they never drew the link and this was on more than one schematic.

The consensus was that, if it is seen to be wrong, in the interest of accuracy & the GP, the error should be pointed out, fixed on the circuit & it noted on the circuit why and it is an amended "not original" circuit. If I have to mod a circuit I normally send an amended circuit, or note it inside the pan.

If we bombard SC with proper qualified critique (no crap) then at least it says that people are reading it and that could justify its existence. What seems to be a big problem is finding people that actually still understand the technology (and that is also an issue in other fields).

The removal of the dodgy clock was one thing, but again consensus was, not having the switching circuit related to the clock, not on the circuit, means that it, like the Tela-Verta, is not actually the circuit of the radio being featured, which is not accuracy.

Marc

Now I see what you are getting at Marcc.

It just could be that the SC AORSM circuit is not even for the Tela-Verta 204C. I'm not sure exactly what it is, but we'll soon find out. Note the different non AORSM type for the 6V6GT - indicating that it was probably originally a 6F6 or EL3.

I'm guessing the circuit shown could be just an example for a radio with a similar valve line-up.

We'll get to the bottom of this.

UPDATE: Tela-Verta broadcast model 54A appears to be the version without the clock.

Valve line-up: 6A8G/EK32, 6U7G/6K7G, 6B6G/6SQ7GT, 6V6GT & 5Y3GT.

Steer back to one regular contributor. At the moment everyone seems to be having a go.

I guess the problem facing SC these days is the increasing shortage of people up to the task of writing authoritatively and well on the subject and willing to put in the effort required to meet a regular deadline.

As for the suggestion of tutorial articles, they could probably simply recycle period articles from RT&H and EA -- assuming they have somebody to research the archives for said material.

Anyway, it has been confirmed that the SC circuit diagram is actually a Tela-Verta model TV54A circuit taken from the 1948 (1947 circuits), Volume 6 of the AORSM.

Tela-Verta TV44P TV54A Circuit Diagram

In some ways you have to appreciate the problem that I have touched on. The long time contributor needed a rest and is not getting any younger.

Next problem, where does SC get a willing horse with sufficient "old" radio knowledge, access to them & an ability & time to write them up?

Marc

All the comments on having Silicon Chip acquire someone with the necessary skills and prior knowledge of valve radios are entirely valid.

I think back to the two 'originals', John Hill from Silicon Chip and Peter Lankshear from Electronics Australia and the great articles they wrote. A lot of time appeared to be spent on doing research and the technical articles on things all restorers need to know - the basics mainly but things like fault finding and the order of precedence to adopt when restoring a chassis more often received a mention than happens today.

Indeed it is a big commitment and to write up five or six pages on each aspect is not a simple task. As I write this I am thinking about the time I spend here keeping this place going. In the last few months I started a new job and it keeps me fairly busy and this has inevitably eaten into time I want to spend on finishing off a couple of site software upgrades which are not going well, development-wise. The planned upgrades will come in time but, yeah, time and knowledge are competing factors with this and they also would with a commitment to write articles for a vintage radio column.

I didn't intend to sound brash when I made my comments this morning. Giving out some stick wasn't the intention (and I am hoping none of what I said was construed that way) and for what it is worth the contributors on the current arrangement are doing a good job with the material they probably have at hand. I still think, however, it would be more beneficial to new collectors and even seasoned ones such as myself if the types of articles I described appeared more often. Even after collecting for more than 25 years, I would consider that I still have things to learn about chassis restoration. I've successfully restored dozens over the years but would like a good reference to be able to double check that everything is being done properly. I do have many of the old magazines but they are currently in storage and hard to get at for the moment. Some years ago, Electronics Australia released a publication called Discovering Vintage Radio. It was a collection of the first few years of Peter Lankshear's articles and if Silicon Chip was to do this with John Hill's articles, even if split into two volumes, this would perhaps be a good compromise.

I'm open to hearing other suggestions.

Brad, I think your suggestions are good ones, and they ought to be put to Leo Simpson.

Apart from providing well-written articles, the authors also need to supply high quality and relevant photographs, too.

As mentioned, my guess is that the required talent is thin on the ground (and getting thinner by the year), hence my suggestion that SC plums its deep archives for material to republish, if it's interested in the topic. In my view, what the Vintage Radio section requires is a permanent sub-editor to oversee quality, etc.

I have to wonder about Leo Simpson's own commitment to the topic. Granted he did front the most recent HRSA Conference and handed out free copies of SC (pushing the Currawong project), but I am not aware of his being a collector or restorer of antique radios himself. I suppose some feedback from the readership would sound out that commitment.

However, in the end, it all comes down to having the right people available and willing to do the work, month in month out. Aye, there's the rub.

I do hope that if this is seen by the publishers, that they take on board that what we are saying, is what we would like, where we think the issues are, and we are not trying to be malicious.

That achieves little and we are trying to be constructive here, expressing genuine concern and should only expressing arguments that have basis in fact.

We should only be interested in continuous improvement concepts: Not having a go at individuals, as that also achieves little. It is the "system" that allows things to go awry that should be fixed first.

Marc

Yes, radio and valve radio circuits are so simple and optimal they are difficult for Humans to understand,
like a complex computer program written in a simple language.

I don’t think radio warrants a regular vintage article in itself any more than vintage computers,
reel to reel recorders, phonograph, telephony, etc. but it’s a shame if no vintage regular article survived.

Vintage Radio was a founding column in SC. I believe that it was the intention that it would be short-lived, perhaps for six to twelve months and then replaced with something else, though when the readers of the new magazine found out they made it clear they wanted the column to stay.

EA followed suit soon after they discovered the popularity of the subject and launched their own Vintage Radio column.

I don’t think radio warrants a regular vintage article

... and that's a very reasonable point of view, given that the magazine's main thrust is to keep pace with current and emerging technology.

I would like to see demographics on the readership of SC. I gather that Leo Simpson alluded to a shrinking readership base when he addressed the HRSA.

I guess my overall point is that if there's to be a Vintage Radio section, then it needs to be of a consistent quality.