Quote:
Originally Posted by maxhifi
May I ask, what sort of sweep frequency generator did you use during the alignment? I have the same RCA TV, and it really has a bad picture after a full recap, reading the above goes a long way to explain why.
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I used an old Eico 368, fully refurbished and converted to
post-modulation markers. This is utter garbage, especially linearity
and accuracy of the sweep. The marker dial is quite
accurate. However I also have a super accurate synthesizer and
use a HackRF with SDRSharp on my computer as a spectrum analyzer, also
very accurate. (You can buy one of those DVB dongles for like $7 from
China and while not 6 MHz wide they make a great spectrum analyzer to set
the markers.) I have not bought a 50s-60s 45 MHz only much
better one since I have some non 45 MHz IF TVs. I can also borrow
the best that money can buy ones if needed (DC to 150 GHZ).
I'll add the pictures I just took.
This one is a video sweep from a DVD player off Digital Video Essentials,
DVD version. The tic marks at top and bottom start at
1.0 MHZ and go up by one MHz steps. You can see the resolution
stopping at about 3 MHz. This is Channel 5 off an agile modulator.
http://videokarma.org/attachment.php...1&d=1454288347
This one is a scope trace of the above, off the CRT cathode. Note that
the 7 pF of the probe noticeable reduces response. You can see the
1 MHz tics which are set at exactly 2 major divisions.
This looks horrible, and is, but oh so much better than what the
service manual shows!
http://videokarma.org/attachment.php...1&d=1454288347
This is the same but channel 12 off a dedicated Ch 12 B-T BAVM-SAW modulator. Just looking at the screen its not different from the above.
http://videokarma.org/attachment.php...1&d=1454288347
This is a single frame from a modulator on a cable box.
http://videokarma.org/attachment.php...1&d=1454288347
This is a single field, not frame, from the modulator and an OTA STB.
http://videokarma.org/attachment.php...1&d=1454288347
Thumbnails appear in wrong order.