31-07-2015, 04:00 PM
(16-07-2015, 08:17 AM)pwdrive Wrote: I always used to fit the series limiting resistors in the anode feeds, it simplifies the understanding of whats going on voltage wise and gives the opportunity to spread out heat dissipation from the said.
Aim for values that will give the same HT voltage at the reservoir capacitor that's specified in the manual as some local osc designs in receivers can be quite critical, eg: if the HT is down by 30 volts the local osc might boot up on MW but not on LW.
Lawrence.
I wasn't too sure where to solder in my diodes. In the end, I opted to solder straight onto the pins of the valve where the transformer leads go. I was a bit concerned about how safe that would be.
I may have said before in the HAM radio Amateur Handbook they were using silicon way back in 1960. I quite like this book because back then the consensus was you should use semiconductors and tubes together with the emphasis on tubes. It stated anyone who chose to use a silicon rectifier should go ahead as they were becoming popular in the HAM field. Who would have thought that all that would end with the tubes being dumped as semiconductors took over?
Should I wish to revert to a tube I'd need a U50 or U78 but, for sure, silicon does provide a cheap alternative.
