Battery voltages for valve portables

[Reelman]

Originally Posted by Wellertcp

When did batteries suitable for battery valve radios cease to become available?

I wrote to EverReady in the early 80s who confirmed they no longer made HT batteries. However Halfords often had old odd ones on the shelves throughout the 80s. Although old stock the prices still rose and before I negotiated a better price they were trying to sell a B136 (90/1.5V) for £5.99 around 1986. It had just enough juice to power up my old Sky Queen for 20 minutes!

In Pickering around 2005 I was in an electrical shop at the foot of the High Street and noticed behind the till along with AAs, Cs & Ds was a 67.5V ER. A bit dusty and completely flat but a worthwhile addition to the collection.

Peter

[Paul_RK]

Originally Posted by emeritus

I seem to remember that my late uncle's 1950's NHS hearing aid (amplifier in a leather pouch hung from the shoulder and worn under jacket, mike clipped to tie, bone conduction 'earpiece' mounted on metal Alice band) used a 45V HT battery.

That sounds rather like mine, except my pigskin pouch just contains the batteries (45V HT, 1.5V LT) and the microphone/amplifier unit clips to shirt or jacket pocket.

As for HT battery availability, yes, my memory is of the final types (B101, B126, B136) disappearing around 1980. About ten years before that many more were still in production, and often cost me much more than the radios I put them in: a Winner 120 certainly did.

Paul

[emeritus]

I guess my uncle's must have been like that. I only saw it a couple of times, and it was a long time ago! As a schoolboy I was more interested in his incredibly smaller replacement. I think I still have the earpiece somewhere.

Vidor were probably the last to manufacture HT dry batteries. I did post some extracts from one of their professional battery catalogues on the forum a few years ago, which showed that many types, including the Winner, were still available for professional customers several years after they ceased being available for consumer retail sale.

[kalee20]

I expect there was a small but important market for such users - military, for instance.

Regarding voltages for portables, 1.5V and 7.5V LT do seem to be the most common. The valves were actually designed for 1.4V nominal, on the basis that a 1.5V battery quickly fell to 1.4V and stayed there for most of its life, thus operation at 1.5V would be limited to a few hours.

The series-connected filament string is really not very 'nice,' the actual filament powers are rather dependent on many variables and thus are not well-defined. The anode (and screen) currents of the valves higher up the chain all flow the filaments lower down, thus bypass resistors have to be used - thus a failing HT battery affects filament voltage (as does AVC action). But, it was easier to make a 7.5V DC supply than a 1.5V DC supply for mains/battery sets, hence the popularity.

Of course, back in the day, a failing valve could be easily replaced - just pop into your friendly local radio shop. Now, they're a limited resource.

Although fragile, careful control of filament voltage does give long life. I have a Vidor CN420a (Dx96 valves, parallel connected), which has been running from a stabilised battery supply set at 1.38V for 14 years, clocking-up approaching 2,000 hours, with the same set of valves. So, it's worth doing properly!

[Oldmadham]

I am often struck by how dissimilar things like this were in the UK & Australia.

Most Oz valve portables used either 1.5v or 9v "A" batteries, the latter maybe due to the liking for 3V4 output valves.

There must have been a few 7.5v radios around, as Eveready & Diamond did make some 7.5v batteries similar to the UK ones.
They also made one with taps on top though it was mainly for use as a "C" battery on (then) vintage radios.

HT batteries were commonly either 45v, 67.5v, or 90v.
The 45v ones were often connected in series to get 90v in a more convenient form factor.

There were also large console radios which ran on dry batteries, & my old work would ship "farm packs", consisting of two very large 45v batteries & an even larger 1.5v battery out to remote communities which used them.

One of the Australian mags had a project for an inverter running off a 1.5v battery to produce HT for valve portables a few years back. (If it was fairly recently, I guess it would have been in "Silicon Chip").

There may well be enough room in the battery compartment of many sets to "bodge up" a 1.5 battery pack for 1.5v or 7.5/9v. as well as one dedicated "D" cell to run the inverter.

[kalee20]

With 9V LT, what was the typical valve line-up Joe? Does the generic Aussie battery radio have an RF stage?

[vinrads]

This is a battery I hadn't come across before, its in very good condition, its is marked up as 45 volts but counting the cells it would have been 48 volts, I am aiming to fit six pp3 I will need to remove the outer casing to do this , giving me 54 volts, the radio is a Braun Exporter ,it performs slightly better for the extra few volts. Mick.

[Herald1360]

Originally Posted by kalee20

With 9V LT, what was the typical valve line-up Joe? Does the generic Aussie battery radio have an RF stage?

A quick search in Radiomuseum suggests the typical lineup was 1T4 1R5 1T4 1S5 3V4. So the answer to your second question is "yes".

[G6Tanuki]

Some earlier dry-battery portables used 3V LT supply, with series dropping resistors to get the voltage down to the 2V needed by valves like the VP23 [which were originally intended for use with a 2V accumulator].

I guess such 'suitcase' type portable radios were obsolete by the end of WWII and the coming of the little B7G 1.4V valves, though I remember seeing - in the early-1970s - one such battery by Ever Ready on sale in Beatties of Wolverhampton. It was a big somewhat flat-looking thing with a 4-pin socket intended to take a right-angled plug. Something similar was used in the WWII-era WS18/30 mapack radios,from memory the HT was 120V

[broadgage]

I can remember a valve hearing aid that used a 22.5 volt HT
battery and a single C Cell for the LT.
Wire ended Russian style valve.
They were vulnerable to breakage if dropped, but replacing the valve was easy with a soldering iron.

I also just recall a farm radio that used a 24 volt external battery supply AND a local HT battery of 45 volts . Worked well with about half the HT and all of the LT being supplied virtually free.

[Cathovisor]

Originally Posted by G6Tanuki

Some earlier dry-battery portables used 3V LT supply, with series dropping resistors to get the voltage down to the 2V needed by valves like the VP23 [which were originally intended for use with a 2V accumulator].

I have an Ekco P151 here that does just this.

[Julesomega]

Originally Posted by kalee20

The series-connected filament string is really not very 'nice,' the actual filament powers are rather dependent on many variables and thus are not well-defined. The anode (and screen) currents of the valves higher up the chain all flow the filaments lower down, thus bypass resistors have to be used

I'm now trawling through the BVWS DVD disc of service sheets looking for more examples of main/battery sets: the Ultra Coronation Twin (mentioned in the Coronation thread today) has R6. R18 and R19 to compensate for the electrode currents of the 5 filaments (4 valves)

[ms660]

For series connected filaments the recommended filament voltage for the 1.4 Volt valves is 1.3 Volts, suggested calcs. for the resistor values for the DK96 etc. series of valves given in here in issue 25:

file:///C:/Users/User/Pictures/dl96%20etc%20in%20series,%20mullard%20filament%20n otes.pdf

Lawrence.

[Oldmadham]

Originally Posted by kalee20

With 9V LT, what was the typical valve line-up Joe? Does the generic Aussie battery radio have an RF stage?

From memory, RF stages were quite common, as distances between the stations in Oz were greater in those days.

Some of the larger portables were quite ambitious in design, with 1 or 2 shortwave bands, as well as MF----no LW though!

The 1.5v battery ones probably didn't have RF stages, though, but I'm pretty sure they also used 3V4 or sometimes 3S4 output tubes as they both have a centre-tapped filament.

[ms660]

Originally Posted by ms660

For series connected filaments the recommended filament voltage for the 1.4 Volt valves is 1.3 Volts, suggested calcs. for the resistor values for the DK96 etc. series of valves given in here in issue 25:

file:///C:/Users/User/Pictures/dl96%20etc%20in%20series,%20mullard%20filament%20n otes.pdf

Lawrence.

Whoops.....3rd link down in here:

https://www.vintage-radio.net/forum/...90&postcount=1

Lawrence.