02-06-2011, 10:45 AM
I got nearly a year from a pair of PP9s in a Hacker Sovereign II, used daily in the kitchen for a couple hours at least. Same story with the VHF Herald in the bedroom - not bad given that I often fall asleep listening to it and wake up in the early hours to find it still playing...
With any transistor set, you really must check the quiescent current and set it up according to the instructions - things drift with age, and it's not unusual to find that the current is wrong... As a guide, anything over ~30mA for an FM set at minimum volume needs investigation (starting with finding the actual answer from the manufacturers information, just in case it's an usual one)
Examples from the Hacker world (what else is there
). Where two figures are given, it's AM followed by FM:
* These use D cells, not PP9s, but included for interest. And note that a faulty microswitch on a DIN socket can cause the Silver Knight to switch to Stereo mode needlessly and double the current consumption (stereo is only available on the DIN socket, so decoder should only be powered when the DIN socket is in use)
Cheers,
Mark
With any transistor set, you really must check the quiescent current and set it up according to the instructions - things drift with age, and it's not unusual to find that the current is wrong... As a guide, anything over ~30mA for an FM set at minimum volume needs investigation (starting with finding the actual answer from the manufacturers information, just in case it's an usual one)
Examples from the Hacker world (what else is there
). Where two figures are given, it's AM followed by FM:- RP18 Sovereign I: 14mA/18mA
- RP25 Sovereign II: 18mA/21mA
- RP35 Herald: 18mA
- RP37 VHF Herald: 21mA
- RP71 Harrier (FM only): 34mA
- RP72 Sovereign III: 20-22mA/22-25mA *
- RP73 Autocrat (AM only): 20-22mA
- RP76 Silver Knight (FM only): 25-30mA Mono, 50-56mA Stereo *
* These use D cells, not PP9s, but included for interest. And note that a faulty microswitch on a DIN socket can cause the Silver Knight to switch to Stereo mode needlessly and double the current consumption (stereo is only available on the DIN socket, so decoder should only be powered when the DIN socket is in use)
Cheers,
Mark
