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  #16  
Old 08-22-2016, 03:21 AM
Tom9589 Tom9589 is offline
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Sandy, you are close but not 100% right. Consumer electronics is supposed to last about a week after the warranty has expired.....
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  #17  
Old 08-22-2016, 08:08 AM
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dtvmcdonald dtvmcdonald is offline
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Why isn't UHF of use now? Our OTA NTSC station is Ch. 39.


My agile modulator goes up well into the UHF OTA range, and
using it to broadcast in the house OTA is a lot more convenient
at UHF. For example, I can watch TV (not just HSN on 39) on my
balcony using UHF on any of my portable TVs, or out in the yard
on my battery color portables (a modern RCA NTSC/ATSC set, or the
Indextron (which will run on batteries) ). ATSC does not work
below the balcony unless I'm out at the boathouse. (Our faux
upscale apartment complex has a lake and "boathouses", really
just gazebos.)

P.S. ... the CT-100 works quite nicely at UHF.
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  #18  
Old 08-22-2016, 09:41 AM
Tom9589 Tom9589 is offline
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When analog TV went away in 2009, all of the television stations' frequencies were scrambled up. The three main stations in Atlanta: 2, 5 and 11 retained their numerical channel designation, but were all shifted into the UHF range. Oddly, our educational station, channel 8, remained at that frequency.

So the UHF frequencies are definitely being used. It's just their format has changed to digital.
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  #19  
Old 08-22-2016, 09:43 AM
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There are fewer low power NTSC channels on the air. I have not known of any in my area in the last 2 years (aside from the VHF ones I broadcast). Now that analog cable is gone in my locale I'm going to have to put a modulator or two on UHF sooner or later. I've always kept my modulators on VHF so my pre-1964 sets could all tune them.
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  #20  
Old 08-22-2016, 01:52 PM
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Quote:
Originally Posted by Kamakiri View Post
That's the AXP I got from you
Glad to help, as I had nothing to put it in.

That old shop had this AX left and that CYP so I grabbed both and passed them along to those who need them..

That Arliss model was the perfect candidate!
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  #21  
Old 08-22-2016, 02:01 PM
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Originally Posted by Tom9589 View Post
When analog TV went away in 2009, all of the television stations' frequencies were scrambled up. The three main stations in Atlanta: 2, 5 and 11 retained their numerical channel designation, but were all shifted into the UHF range. Oddly, our educational station, channel 8, remained at that frequency.

So the UHF frequencies are definitely being used. It's just their format has changed to digital.
In Philadelphia, 6-ABC and 12-PBS stayed on VHF, 3 and 10 went to UHF. Two of the seven DT stations in the Harrisburg area are VHF. One stayed on 8 and the other went from 27 to 10, and is a bigger reception problem than ever now.

With NTSC being extinct in our area, I wish it was all on UHF. We STILL need bigger VHF antennas and broadband combos that are even larger: sigh: making our rooftop antennas very obvious.
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  #22  
Old 08-24-2016, 12:47 AM
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CTC-5 was looking great until it blew the horizontal sweep output fuse tonight and I lost HV. Fuse is a .300 amp 250 volt C type. Assuming it is not a slow blow fuse, correct?

Now I am really gonna leave it be until someone more knowledgable than me can run some key diagnostics to make sure the set is running ok. Anything obvious I should look for that may have caused this?

Figures!!! Just got the convergence all set up!
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  #23  
Old 08-24-2016, 12:55 AM
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  #24  
Old 08-24-2016, 06:54 AM
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Quote:
Originally Posted by bigaudioal View Post
CTC-5 was looking great until it blew the horizontal sweep output fuse tonight and I lost HV. Fuse is a .300 amp 250 volt C type. Assuming it is not a slow blow fuse, correct?

Now I am really gonna leave it be until someone more knowledgable than me can run some key diagnostics to make sure the set is running ok. Anything obvious I should look for that may have caused this?

Figures!!! Just got the convergence all set up!
Key with any roundy is to adjust the horizontal linearity/efficiency coil for minimum H output cathode current (it will be a dip) using a 0-250mA or 0-500mA meter in series with the cathode. Should be covered in sam's horizontal adjustment procedure.

It is also wise to look at the H osc. waveform on a scope to make sure it is correct, and check the grid drive of the H output tube before the current dip to ensure the tube is being driven properly.
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  #25  
Old 08-24-2016, 07:03 AM
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Quote:
Originally Posted by Electronic M View Post
Key with any roundy is to adjust the horizontal linearity/efficiency coil for minimum H output cathode current (it will be a dip) using a 0-250mA or 0-500mA meter in series with the cathode. Should be covered in sam's horizontal adjustment procedure.

It is also wise to look at the H osc. waveform on a scope to make sure it is correct, and check the grid drive of the H output tube before the current dip to ensure the tube is being driven properly.
Thanks. Nick Williams is going to drop by sometime soon and hopefully help me check all this. I do know where the horizontal linearity/efficiency coil is and this check looks fairly simply. Just set meter to mA's and hook between chassis ground and the exposed top of the horizontal sweep output fuse (after replacing it with new fuse). Then tweak the coil for the minimum mA reading.
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  #26  
Old 08-24-2016, 07:38 AM
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Leave fuse out. Amp meter completes the cathode connection.
Usually you also put a cap ( .01 IIRC ) across the meter too.

73 Zeno
LFOD !
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  #27  
Old 08-24-2016, 10:00 AM
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Most procedures I've read call for a .47 cap, but in my experience the cap usually don't make a difference.
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  #28  
Old 08-25-2016, 10:08 AM
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Thanks fellas!
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  #29  
Old 08-30-2016, 02:04 PM
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CTC-5 update. Got a beefier variac and a few replacement fuses for the horizontal sweep output circuit. Powered the set back up at 115 volts and measured the current on the horizontal circuit. Was reading 230 mA. I hear it should be around 190. So need to adjust the horizontal efficiency coil. However, the coil is frozen up solid. Need to pull the chassis and try hitting the coil with a hair dryer or heat gun to free it up so I can properly adjust it.

Also need to figure out a way to secure one of the dynamic convergence control pots to the chassis. The locking tabs that did secure the pot were broken off and the pot just hangs by its wires. Makes it virtually impossible to adjust while set is playing. IIRC, it is the blue gun control (Tilt and Amp). Will work on these two issues over the next few days.
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  #30  
Old 08-30-2016, 02:19 PM
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6CB5's cathode current AND high voltage varies with brightness. Checking cathode current on 6BK4 (850 microamps) is part of the procedure. If you adjust the HV for 24 kV(?) and the current at 6BK4 falls below that value, the eff coil needs readjusted. Lots of interaction.I'll check my library of RCA stuff to see the exact procedure and email it.

Hopefully the eff slug was not adjusted with a metal allen key, which splits it, requiring very careful removal by hand, using a drill bit.
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