10-10-2016, 08:13 PM
(This post was last modified: 10-10-2016, 08:30 PM by Mike Watterson.)
Saba does this (or very similar) to have push pull mono and single ended stereo on many radio models. The bias on the Saba changes appropriately, so push pull mono is a bit more than twice the power. Only the later versions had even an option for a stereo decoder, the earlier versions would only have used stereo with a separate reel to reel tape or record player. Hence the mono mode was more "important".
Yes it did puzzle me for a moment.
The Saba sounded very good indeed, but the motorised automatic station search was a bit dodgy due to bad contacts on the search button bank. It also had funky adjustable FM IF bandwidth (dealer/factory setting, not for users!)
The other odd output scheme on one Pye and many Grundig battery mains sets is EL42 or similar sharing a transformer (different taps) with a DL94 or DL96, so you get MUCH more volume on mains.
OTH the rather mad Philips LX527AB (various odd features and a later model swaps ONE of two DAF91 for a DAF96 so as to add a DM70!) has two DL94 in push pull, at slightly less than normal 90V HT due to NINE volt LT (to ensure nice bias!). But on AC mains the HT for the DL94 is higher than the rest of the set and is I think about 138V*! It uses more negative bias on mains and close to class B and maybe slightly beyond limits of the valves (but they are Philips valves, right?) (It's certainly loud on mains.)
http://www.radiomuseum.org/r/philips_lx527ab_2.html
It's got a very unusual aerial system too. No need for a SW whip!
[* Edit may be 160V HT, then -12V = 148V !]
Yes it did puzzle me for a moment.
The Saba sounded very good indeed, but the motorised automatic station search was a bit dodgy due to bad contacts on the search button bank. It also had funky adjustable FM IF bandwidth (dealer/factory setting, not for users!)
The other odd output scheme on one Pye and many Grundig battery mains sets is EL42 or similar sharing a transformer (different taps) with a DL94 or DL96, so you get MUCH more volume on mains.
OTH the rather mad Philips LX527AB (various odd features and a later model swaps ONE of two DAF91 for a DAF96 so as to add a DM70!) has two DL94 in push pull, at slightly less than normal 90V HT due to NINE volt LT (to ensure nice bias!). But on AC mains the HT for the DL94 is higher than the rest of the set and is I think about 138V*! It uses more negative bias on mains and close to class B and maybe slightly beyond limits of the valves (but they are Philips valves, right?)
(It's certainly loud on mains.)http://www.radiomuseum.org/r/philips_lx527ab_2.html
It's got a very unusual aerial system too. No need for a SW whip!
[* Edit may be 160V HT, then -12V = 148V !]
