03-11-2017, 11:57 AM
TV22mod1.pdf (Size: 808.32 KB / Downloads: 8)
Hi.
I'm now going to gradually upload the circuits which have been modified in this TV22.
Firstly is the Video amp, part of what i did yesterday.
Before I did the mod I decided to try and check the frequency response of the existing EF91 amp. I used a function generator and used frequencies from 250Khz up to 3.5Mhz. The response was fairly flat to 2.5Mhz. After fitting the 30FL1 I did the same test with the original values as per the Bush. The results were good up to around 2Mhz then the level increased above it to 4.5Mhz, so the cathode caps were changed to flatten off the response. Results are brilliant with a higher video level. An excellent and probably a good thing to do on any TV22. The cathode follower of course is low impedance and this reduces stray capacitance.
