Moderators: Dave Moll, Andrew Davie, Steve Anderson
Klaas Robers wrote:Yes this was the LDK-3 camera. You see the three deflection units for the 3 plumbicons, Red at the top, green in the middle, blue at the bottom. On the side of these deflection units, the flat black boxes with many holes in it, are the pre-amplifiers with each two nuvistors as an input stage. The other parts is all transistors. The thick cable contains 96 wires, going to a rack with electronics, the camera itself is kept as stupid as possible. This camera comes from about 1970.
Harry Dalek wrote:..I will just wait on any suggestions Steve has on the 12AT7 12XT7 deflection update.
Steve Anderson wrote:Harry Dalek wrote:..I will just wait on any suggestions Steve has on the 12AT7 12XT7 deflection update.
Heck Harry! Somehow that's 'slipped through the cracks', i.e. I forgot about it...I'll get on the case soon...just one other post regarding SSTV to do first...clear some 'real work' stuff, off I go...
Steve A.
Steve Anderson wrote:There's more to this change than just altering the supplies...my suggestion (untried)...the +8.0v value will/may alter depending on your ramp amplitude and average voltage. I suggest getting those done before building this...there may be some changes required as a result...
R101, 105, 106 & 109 need to be mounted right on the socket pins.
Steve A.
Deflection 101.gif
Steve Anderson wrote:OK, let's see. What positive and negative voltages do have available?
What tubes are you planning to use in these stages?
That's a start, the ECC91s as illustrated are very different to what you may have on hand, it was just an example...
Also if you can provide the ramp amplitudes available, both peak-to-peak and absolute values would help (min. +2, max +10, 8V p-to-p, or similar).
Steve Anderson wrote:Hmm, the use of attenuating probes on 'scopes does cause a bit of confusion to those new to using them. I suggest finding a couple of 'voltage references' such that you can ensure you've 'got it right' in your head. This is made worse by more modern 'scopes often doing it for you. Some sense you're using a x10 probe and do the adjustment for you, some don't. A potential source of (large) errors. Often it's obvious, you're unlikely to get 60V out of a circuit running off a 9V battery unless it's designed to do that. If still slightly unsure use a meter for DC or low-frequency signals to confirm or otherwise what you might find.
Use a 9V battery (on DC-coupling) as a rough reference and make sure the 'scope and/or you get it right. Or a transformer with a (say) 12V secondary where the peak-to-peak voltage should read about 34V p/p, maybe up to 20% more with no load.
I had to make some adjustments in my head when I encountered this on a digital 'scope for the first time. Below is an example from my 'scope. The x10 setting in the right-hand column can be changed to x1, x10, x100 and x1000 for really high voltages. So the voltages at the bottom are the 'real' volts-per-division voltages, no need to multiply them x10 in your head...
Yes, check every time you use a meter that the low-battery warning hasn't come on, an easy source of errors and confusion...and also during the time of usage, after 30 minutes it may come on...
Return to Construction Diaries - Electronic Televisions
Users browsing this forum: No registered users and 3 guests