Not sure why, perhaps it is googlemail but I rarely get notifications from this site on any responses to thread, so I apologise to Amie and Ed for not being back sooner, I just did not know.
I have been working on the project in the background and had some success. I am still using the same if transformers as before only with a small series cap to to the grid of the next stage, but then having to add a 100KOhm grid resistor to the EF81's. It may be a little narrower in response, but very little.
What I have done is changed where I take the sound IF from, I am now across the output of the tuner and not from a trap on the video IF. This gives better results, not 100% perfect, but reasonable.
I have done a video that can be watched here: - https://youtu.be/UHnmOmn_gPw
I go on a bit sorry, as I show a few things such as what I use to generate a 405 signal and a bit of the TV. There seems to be a copyright issue with the music from the BBC interlude so I may have to edit it at some point for the 60 seconds worth of Interlude playing on the TV!
Adrian
I have been working on the project in the background and had some success. I am still using the same if transformers as before only with a small series cap to to the grid of the next stage, but then having to add a 100KOhm grid resistor to the EF81's. It may be a little narrower in response, but very little.
What I have done is changed where I take the sound IF from, I am now across the output of the tuner and not from a trap on the video IF. This gives better results, not 100% perfect, but reasonable.
I have done a video that can be watched here: - https://youtu.be/UHnmOmn_gPw
I go on a bit sorry, as I show a few things such as what I use to generate a 405 signal and a bit of the TV. There seems to be a copyright issue with the music from the BBC interlude so I may have to edit it at some point for the 60 seconds worth of Interlude playing on the TV!
Adrian
Learning as I go!
Youtube EF91 Valve
Youtube EF91 Valve
