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Model creation - comments for different fields

Martin Renz Ernst Erb Jürgen Stichling Vincent de Franco Bernhard Nagel 
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Forum » FAQ - click for boards » FAQ about the radio pages » Model creation - comments for different fields
Ernst Erb
Ernst Erb
CH  Articles: 5493
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03.Sep.12 20:39

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To help creators of models how to fill in different fields which are not clear without instruction, we state some rules here.
For thousands of members who upload and about 30 admins who control (two of them), some quality is only possible with some rules.


Field: Voltage
(careful, the word Volt is automatically added, last must be a number)

We have a selection box for the type of power supply (s) and an entry field.  In combination with one another, they can hold accurate information.  It gives us many ways to describe the power supply (s).

Gradually we have expanded the entry field.  I've expanded it now from 48 to 100 characters. The Reason: For the United States (and elsewhere), we should be able to distinguish the frequencies. Also, one can enter longer descriptions, such as “Storage Battery”.  For models in non-German speaking countries, we prefer the description in English!  Using the appropriate language of the market-state is also possible.

Principle:  We do not need to update the existing models. At the end there is automatically the expression “volt”. Blank space between expressions!

1.      Easy entry. No sign: Examples: 115 or when known (eg diagram) 115 = 105 to 125
      (instead of today's 105 - 125)

Frequencies: specify if possible as 25 to 60 cycles (highest frequency is always 60, since only the lower frequency is the limiting factor (lower frequencies require a larger transformer).  Example 25 to 60 or 50 to 60 cycles 115   Exception:  When there are different model numbers for the models with different transformers, then separate models should be used with the single frequency range.

Several transformers are possible: either transformer 110 or 220 Example: Either transformer: 25 to 60 cycles 110 volt or 50 to 60 cycles 110 volt or 50 cycles 220 (89 characters).


2.      Use of the dash - and semicolon ; characters

-Dash – Describes the voltage range. New Method = to. For example: 110 - 240, better 110 to 240

; Semicolon indicates several possible settings for a single voltage source.  For example: 110; 145; 200; 240. With transformers with multiple taps, state the number of taps.  For example: 110 to 240 - or if known: > 2 taps: 110 to 240, better  4 taps: 110, 145, 200, 240

Variation:  Some manufacturers (eg Philips) have transformers with tap ranges that join seamlessly together. For example: 5 taps: 100 to 130, 130 to 160, 160 to 190, 190 to 220, 220 to 250

3.       Use of the &. 

This means requires several voltages to operate:  For example 2 & 90 (or if known: 2 & 2 x 45)

If possible, take into account the bias cell, eg 1.5   If possible, specify the composition of power sources, eg 2 x 4.5 or 6 x AA 1.5

3 Examples for 9 volt: 1 x 9 / 2 x 4.5 / 6 x AAA 1.5

The codes to use for the battery type: A, AA, AAA, C, D, lantern (= 6 V with spring top).

See also Wikipedia.

4.      Use of the slash /.

This means other power supply options. This is clearly not for beginners, so we prefer to use either 2 & 90 or AC 110.  For example: Either 1.5 & 2 x 45 or AC 105 to 125 or DC 105 to 125

Adapters: or external DC

Example: Either external DC or 6 x AA 1.5


5.      The word “Volt” follows automatically, therefore the last information entered should be a number
      and there should not be a dot at the end.


Here is a table that summarizes the new methods with examples:

Voltage Description

New Method Examples

Old Method Examples


Single Voltage



No change.  Do not add the “V” at the end, as this is included on the model page.


115 = 105 to 125

105 - 125

Use the nominal voltage first (if known), followed by the voltage range


50 to 60 cycles, 115



25 to 60 or 50 to 60 cycles, 115


Do not create separate models for radios that have different AC power frequency ranges unless the models have different model numbers

Voltage and Frequency Range

25 to 60 or 50 to 60 cycles, 115 = 105 to 125



Multiple Transformers (Example: 110V or 220V)

Either transformer: 25 to 60 cycles 110 volt or 50 to 60 cycles 110 volt or 50 cycles 220


Use the word “Either”

Transformer tap settings for a single transformer


4 taps: 110, 145, 200, 250



2 taps: 110 to 240



5 taps: 100 to 130, 130 to 160, 160 to 190, 190 to 220, 220 to 250



Several Required Voltages


2 & 90

2 & 90

No change

2 & 2 x 45

2 & 2 x 45

Show the composition of power sources if known as shown in this example ( 2 x 45 is preferred over 90)

1.5 & 6 x AA 1.5


Add battery type if known.  Acceptable battery types are A, AA, AAA, C, D, Lantern (= 6V with spring posts).

1.5 (Bias Cell) & AC 105 to 125


Bias cells should be included as a power source

Multiple Power Options

Either 2 & 90 or AC or DC 105 to 125

2 & 2 x 45/115

Use the word “Either”

Either External DC Adapter or 6 x AA 1.5



This is the result of a personal discussion with John Kusching, USA, when visiting me in Switzerland. He is one of the most active members at and had then created more than 1500 new models.

This article was edited 03.Sep.12 20:48 by Ernst Erb .

Ernst Erb
Ernst Erb
CH  Articles: 5493
Schem.: 13672
Pict.: 30672
06.Nov.16 18:24

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Exceptions and details:

It is good to always give details and reasons - too much is here better than too few - or even wrong!

Single Voltage: If the from-to voltage is known, we add it too - like 50-60 Hz, 115 = 105 to 125.
Multiple Voltages (Transformer tab settings): Specially in Europe an AC model normally uses a transformer with different possible input voltages like 110 - 250 volt. If known we give the different voltages:
110-250 = 6 taps: 110, 125, 150, 200, 225 or 250. In Canada etc. you would put the cycles in front if it is also for 50 Hz (50-60 Hz).

Some manufacturers would use single voltages - also on schematics but in fact the set was made to operate within a range of voltages - for example from 110 to 117 or 120 volts within specification. But even then the set can be run on 105 volts or 125 volts, but is not anymore within specification: Parts may suffer ...

Where known, for instance by SAMS schematics, we state the given voltage and voltage range. In times where there are many proposals pending we should refrain changing such single items or giving multiple voltages when there is a range which in fact does not matter! 

Added March27, 2017 by EE:
If we find a different single voltage on the chassis than on the schematic, we do it like this:
50/60 Hz, label 115, schematic 117 = 105-125

as you see it on the model General Electric Phono-Mic Preamplifier UPX-003B.

This article was edited 27.Mar.17 11:17 by Ernst Erb .

Ernst Erb
Ernst Erb
CH  Articles: 5493
Schem.: 13672
Pict.: 30672
27.Mar.17 11:20

Count of Thanks: 2
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Or member Thomas Albrecht (Dr., physicist) wrote this in an eMail:

"One thing which I will add is that the difference between "today's higher line voltage" and the voltage ranges seen in the early days is not as significant as often discussed.  There have been many enlightening discussions on ARF on this topic, with Alan Douglas (before he passed away) often pointing out that there were big regional differences in AC voltage within the US in the 1920s and 30s, with the top end of the range generally being 125 volts.  When a range was specified, it usually went up to 120 or 125 volts.  

Today's spec is 120 V +/- 5% (114 - 126 V), with a few people reporting exceptions of 127 V (I have not heard of anything higher on a sustained basis).
During or shortly after WWII, the official nationwide nominal voltage became 117 VAC +/- 5% at the outlet, and in the 1960s, this was changed to 120 VAC +/- 5% at the service entrance, which is where it remains today.  There has been some discussion as to whether there is any real difference between 117 VAC at the outlet and 120 VAC at the service entrance.  Some think that the change to 120 VAC at the service entrance was simply a redefinition of the status quo in a manner that was easier for the utility to measure and verify, since they could not be responsible for wiring and loads inside the house.
Bottom line is that for post WWII radios, it is disputable whether there has been any increase in the top end of the supply voltage at all, and for pre-WWII radios, most were designed to cover quite a range, to handle all the local voltage variations.  There are cases of radios that seem to overheat a bit at 121-125 VAC (probably the most commonly seen voltages today), but we also don't know at what temperature they really ran when they were new on the range of voltages they experienced.
The idea of "today's higher line voltage" gets repeated so often that it is often accepted as fact, and to be some kind of huge difference, like 15 volts.  Changes in the top end of the range are not very significant, although changes in the bottom end of the range are certainly real.  It's pretty rare to see voltages below 115 VAC these days."

Second eMail:

"I took a look in some old literature to see what kinds of voltage ranges tubes were designed to handle.  Curiously, the RCA Radiotron Designers Handbook (I have the 3rd edition) and Receiving Tube Manuals seem to be silent on this matter (at least with respect to specific ranges for filament voltage), but I did find some verbage the Sylvania Tubes Technical Manual, 5th edition, 1943, with the following surprisingly accommodating specs (page 15):
"6.3 volt heater types ... are designed to operate satisfactortily over a range of voltage from 5.7 to 8.5 volts."
"Owners of farm lighting plants operating with a 32 volt storage battery can procure receivers designed especially for that use.  The 0.3 ampere types are usually connected in series for this service.  The voltage range for lighting plants of this type is from 28 volts to 40 volts.  If the voltages across the tube filaments are adjusted at normal for the 32 volt condition, no adjustable resistor will be required for satisfactory operation."
"Receivers designed to operate on 115 volt DC lines usually employ tubes connected in series, and with sufficient fixed resistance introduced the heater current is kept normal with 115 volts applied.  Under normal line voltage variations from 100 volts to 135 volts no additional adjustable resistors will be necessary."
"The universal type of receiver so common at the present time employs the series filament method of connection described in the previous paragraph.  In general, no special precautions are necessary to take care of line voltage fluctuations."
These are surprisingly wide ranges, and I wouldn't be at all surprised to find some narrower ranges, such as +/- 10% specified somewhere.  Maybe Sylvania wanted to accelerate the demise of tubes so they could sell more?  :)
Still, overall I find that people like to specify rather tight specs that may not be supported by manufacturer's original specs.
Absolute max specs on plate and screen voltages, of course, were specified precisely and should be followed.  But heater specs seem to be rather soft."
Sometimes the entry of 110 - 250 V is in fact not quite correct as Mike Edwards (UK) pointed out. He gave a good solution:

" 110v 125v 150v   200v 225v 250v . There is clearly a large gap in the range between 150 and 200, even though it is also marked as 110 - 250 volt.
It is therefore better that the individual voltage settings are listed in the voltage field. Anything different can be added into the "notes".
I would agree that a "Frequency" e.g. 40 to 60 Hz, field would also be useful information to record if it is known, as some British radios were designed to work to as low as 40 Hz mains frequency.."

This article was edited 27.Mar.17 12:16 by Ernst Erb .