#136
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oh yea. ive had my fun building DIY SMPS circuits. WEEEEEEE
especially when your not pushing the gates hard enough, you power up your circuit, works for a little bit then... KERRRPLOWWWWWW weee yea what fun.... |
#138
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Of course a flyback is a type of switching power supply (having designed a couple).
And sweep tubes were commonly used in lower cost amateur SW transmitters, probably running pretty close to Class C (I think you could get 100W PEP SSB out of a 6JE6). You tuned the final to minimum current. |
#139
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Kevin Last edited by Kevin Kuehn; 02-10-2011 at 12:22 PM. |
#140
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Perhaps the added cost was not justified? I read that one resistor was saved in the matrix of the 21CT55, vs the CT-100. You might be surprised the lengths OEMs go to for cost reduction; some of it borders on a safety risk, especially with cars.
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Evolution... |
Audiokarma |
#141
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The resistor elimination in the 21CT55 matrix from the CT100 design was a patent dodge. RCA did not want to pay royalties on I/Q demodulation. Well, thats the story I heard. RCA was known to do almost anything to avoid paying royalties.
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John Folsom |
#142
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I do not have a CTC2B chassis to test my theory, but one must rule out the possibility that the CTC2B chassis does not properly decode the color signal transmitted by an NTSC broadcast transmitter. The two color signals, I and Q, that are trasnmitted by NTSC standards are in quadrature. In the CTC2B the decoded chroma, Q and R-Y, are not. When a quadrature signal is encoded, it must be deconded in quadrature if crosstalk is to be minimized. If I am right, the CTC2B chassis is inferior to the CTC2 chassis when decoding an NTSC broadcast. Now, it is always possible that some stone has been left unturned by me. Perhaps eliminating the one insignificant-in-cost resistor in the CTC2B matrix somehow negates the not-in-quadrature problem. I don't know. BTW: I believe it was probably Philco that RCA was dodging. Pete Last edited by Pete Deksnis; 02-15-2011 at 10:51 PM. |
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Comparisons before and after FBX replacement.
Here are preliminary comparisons of the original FBX vs the replacement FBX installed in my 21CT55. The screen is still too wide, must be the original yoke is more sensitive then the newer yokes intended to be driven by the replacement FBX. No, I wont try to find a newer yoke………..Tom
Last edited by Tomcomm; 02-26-2011 at 05:11 PM. |
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When I had to come up with a flyback for my CBS field sequential color adapter (the original was missing) I had to experiment with various things to get the replacement to work with the yoke. I also had too much width. I added an inductor paralleled by a resistor in series with the yoke. Maybe something similar would work for you:
http://www.earlytelevision.org/cbs_c...storation.html |
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Hobble-up Width Control
Steve, thanks for your interest in my 21CT55 reactivation. The new FBX is very efficient, delivering 32kv maximum ultor and 800v boost with B++ of 398v. Fuse current is same as HOT cathode and runs at only 174ma. B++ is limited with power resistors in the power xformer hv secondary so I can select three B++ voltages with 115vac input from my Variac: Low is 374v @ 160ma HOT, Med is 395v @ 170ma HOT, High is 420v @ 182ma HOT. After running for 3 hours at Med, FBX is bearly warm at B++ of 395v. Excessive screen width is the only major problem. All RCA's CTC7 and above have no width control. They must rely on tight spec'd parts in the Horz/EHV system to give just the right over-scan.
Your experience with using inductors to load the FBX and bleed-off drive to the yoke is consistent with my Fink '57 TV engineering handbook descriptions of width controls . Most of them were shunt where yours is series dropping. I intend to try various schemes to pull mine in. The preliminary pics I posted above were somewhat disappointing to me. I definitely have chroma leakage in the Q channel since I don't have the proper output filter values installed. Also my camera was on AUTO and bad focus. Here's some full manual pics. The first pic is a stitch of extreme crop of new vs Sony Pro. Q chroma leakage is obvious: Last edited by Tomcomm; 02-28-2011 at 03:01 PM. |
Audiokarma |
#146
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My 7 and 9 both have a plug on the yoke you can move around to get the desired width, while my 4 has an actual switch.
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Evolution... |
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my 9 has that plug also.these sets produce some of the most pleasing colors.i have it along side of my zenith space command and the 9 s flesh tones are remarkable.my xl100 and the zenith chromacolor with the 25vdmp22 are better,but not that much.love those old rcas!
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#148
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What are the other 4 pics? Chroma dots on every other one? - like with and without 3.58 trap in the luma.
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#149
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the HOT circuit for minimum current which, at least in my B&W sets is also the best linearity. I imagine it's the same in color sets too? Cliff |
#150
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RCA was the last major mfr. to use intercarrier audio. I guess Sarnoff didn't want to lower himself to paying royalties to Motorola Inc.
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Audiokarma |
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