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1100 man · 26th Aug 2017, 10:32 pm

Hi Matt,
I'm following your progress on this project with interest!! There are some interesting challenges especially, on the RF side of things.
With regard to the HT rectifier, I've just replaced the metal rectifier on my Pilot with a silicon diode. I did some digging around various threads and concluded that for TV's a series resistor in the order of 25 ohms or so is about right. 100 -300R is more suited to the lower current stuff like radio's etc so will cook with the HT current the TV will take.
I used a BY133 rather than an 1N4007, partly because I had some and partly because they are more TV related. The BY127 was used in many 70's sets. The BY133 looks like it has much the same spec and works fine with a 25R series resistor, the HT is spot on. It also seemed to be good practice to put a 1000pf 1000V cap in parallel with the diode to reduce the spikes produced when the diode turns off.
Hope that helps
Cheers
Nick

26th Aug 2017, 10:32 pm	#37
1100 man Octode Join Date: Apr 2016 Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK. Posts: 1,377	Re: And the next one! a GEC BT2147 Hi Matt, I'm following your progress on this project with interest!! There are some interesting challenges especially, on the RF side of things. With regard to the HT rectifier, I've just replaced the metal rectifier on my Pilot with a silicon diode. I did some digging around various threads and concluded that for TV's a series resistor in the order of 25 ohms or so is about right. 100 -300R is more suited to the lower current stuff like radio's etc so will cook with the HT current the TV will take. I used a BY133 rather than an 1N4007, partly because I had some and partly because they are more TV related. The BY127 was used in many 70's sets. The BY133 looks like it has much the same spec and works fine with a 25R series resistor, the HT is spot on. It also seemed to be good practice to put a 1000pf 1000V cap in parallel with the diode to reduce the spikes produced when the diode turns off. Hope that helps Cheers Nick