23-06-2020, 01:08 PM
(This post was last modified: 23-06-2020, 01:18 PM by Mike Watterson.)
The battery cell voltage of a nominal 1.5V Zinc Carbon falls pretty fast from 1.6V to 1.45V and then under 1.4V. Hence the 1.35 recommendation and the 1.4V spec. In normal usage there would be little time above 1.4V and replacement around the 1.05V to 1.1V, volume gradually degrades with failing HT, but Local Oscillator stops dead at some point with falling LT. Vidor actually explain the symptoms as to when to replace HT or LT pack on the sets with separate packs. On the 250mA sets the small LT packs needed replaced twice as often as HT. Larger LT packs and combo packs were designed that the LT and HT would exhaust at the same time. Since the o/p was class A on most sets that was fairly accurate. The sets with push pull etc might have also had an RF preamp, so the main concern on combo packs for them was the LT.
The Zinc Chloride is not much different to Zinc Carbon except at higher currents there are lower internal losses. The x5 life of Alkaline over Zinc is only applicable at the sorts of massive currents of a floodlamp or motor that ought to use NiMH or Lead Acid historically. It's more like x2. Thus a AA Alkaline is similar to Zinc B cell and an D Alkaline can replace a F cell. An F cell is 50% bigger (longer) than a D, but the x4 F in parallel in an AD4 pack gives much lower resistance than the two smaller cells in parallel in an AD35 (which changed the the size of cells from a cell larger than D to D during lifetime). A C Alkaline can replace a Zinc D, or one D Alkaline replace a pair of D, except not quite the larger cells in older AD35, so I put 2x Alkaline D in a AD35 box. The 250mA sets certainly used the original higher capacity cells in an AD35, but still would have used that twice as often as the HT pack.
The B114 would have had a short life, but the USA 1941 to 1946 models often used a single D cell in a holder for maybe less than 18 hours life. Like DAB Radio
though some early DAB sets only last 6 hrs on a charge.
The 5214 AD3 pack had EIGHT F cells in parallel. It was intended for long service. Some USA Farm Radios (what we would call Table models) from 1938 when All Dry came in there had an LT pack with SIXTEEN F cells!
As an even more aside, Sylvania did button base versions of the 1938 1.4V dry battery valves they developed. Loctal base. The Loctal button base pins fit an octal plug and thus into an octal socket. The 1940 RCA B7G valves (indirect for mains and the 1.4V alldry) are essentially just miniature versions of the Sylvania loctal & Octal types. The first step in Philips versions that weren't a copy of the RCA came before Philips / Mullard did the B7G, they were the Rimlock / B8A. The DK40 was superior to the DK92 and the RCA original. The DK92 and not quite compatible 1L6 replaced the DK40 and USA 1LC6 for "decent" shortwave. The DK96 is poor for SW.
The original RCA B7G battery valves used nickel filaments because such small filaments couldn't be done accurately enough for series. The Telefunken 1940s series had all different currents to minimise consumption, so used the NiCd as a regulator and LT for mains. Philips not only cut the current in half for the B7G series but with improved diamond dies also used tungsten. So the 25mA series have more fragile but longer life tungsten rather than the nickel of the original 50 mA series RCA design.
Note a 10% overrun about halves the life of a tungsten lamp.
Edit forgot to click on Add!
The Zinc Chloride is not much different to Zinc Carbon except at higher currents there are lower internal losses. The x5 life of Alkaline over Zinc is only applicable at the sorts of massive currents of a floodlamp or motor that ought to use NiMH or Lead Acid historically. It's more like x2. Thus a AA Alkaline is similar to Zinc B cell and an D Alkaline can replace a F cell. An F cell is 50% bigger (longer) than a D, but the x4 F in parallel in an AD4 pack gives much lower resistance than the two smaller cells in parallel in an AD35 (which changed the the size of cells from a cell larger than D to D during lifetime). A C Alkaline can replace a Zinc D, or one D Alkaline replace a pair of D, except not quite the larger cells in older AD35, so I put 2x Alkaline D in a AD35 box. The 250mA sets certainly used the original higher capacity cells in an AD35, but still would have used that twice as often as the HT pack.
The B114 would have had a short life, but the USA 1941 to 1946 models often used a single D cell in a holder for maybe less than 18 hours life. Like DAB Radio
though some early DAB sets only last 6 hrs on a charge.The 5214 AD3 pack had EIGHT F cells in parallel. It was intended for long service. Some USA Farm Radios (what we would call Table models) from 1938 when All Dry came in there had an LT pack with SIXTEEN F cells!
As an even more aside, Sylvania did button base versions of the 1938 1.4V dry battery valves they developed. Loctal base. The Loctal button base pins fit an octal plug and thus into an octal socket. The 1940 RCA B7G valves (indirect for mains and the 1.4V alldry) are essentially just miniature versions of the Sylvania loctal & Octal types. The first step in Philips versions that weren't a copy of the RCA came before Philips / Mullard did the B7G, they were the Rimlock / B8A. The DK40 was superior to the DK92 and the RCA original. The DK92 and not quite compatible 1L6 replaced the DK40 and USA 1LC6 for "decent" shortwave. The DK96 is poor for SW.
The original RCA B7G battery valves used nickel filaments because such small filaments couldn't be done accurately enough for series. The Telefunken 1940s series had all different currents to minimise consumption, so used the NiCd as a regulator and LT for mains. Philips not only cut the current in half for the B7G series but with improved diamond dies also used tungsten. So the 25mA series have more fragile but longer life tungsten rather than the nickel of the original 50 mA series RCA design.
Note a 10% overrun about halves the life of a tungsten lamp.
Edit forgot to click on Add!
