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 Post subject: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Mar Sun 31, 2019 7:39 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Waukegan, IL
I am wondering if this is too low for cathode current on the 6DQ5 even though you do want a low value. Im measuring only 35ma with an analog as well as a DVM. I have a socket adaptor with the break for pin 3. i left pin 6 open, since 3 and 6 are jumperedat the tube socket anyway. So, meter is between pin 3 and ground. i havent tried to adjust anything. Even Sams is saying 185ma at this point. I think its weird.

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Tony Pignaloni


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Mar Sun 31, 2019 10:14 pm 
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Location: Waukegan, IL
I tried a different analog meter. Now I have 120ma. Sounds more normal.

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Tony Pignaloni


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Mon 01, 2019 9:32 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
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Location: New Hampshire
You also have to put a cap in // with the meter. Sams gives value.

73 Zeno
LFOD !


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Mon 01, 2019 10:57 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Waukegan, IL
Tried it with a cap. Maybe even this meter is no good. I think i should be seeing a value closer to 200ma.

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Tony Pignaloni


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Tue 02, 2019 12:37 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
I normally fit a 1 ohm resistor in the cathode - and leave it there. I always get a more sensible reading this way.
Old HMV TVs would always have this from the factory.

Measure voltage across that. Read mV = mA.

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Thu 04, 2019 7:35 pm 
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Location: madison,wisconsin
Here is my CTC-11 showing Cathode Current, I do not like to use any of my nice Digital meters, your suppose to place a Capacitor across the terminals, but I bought one of these Seco Test jigs that already is set up, its a tight fit placing the Cap on the H-output, but it gives you some idea
my Chassis Cathode current is 170MA on the Seco which the meter movement is off, but measured again with my Agilent Bench Meter ( which I do not like to use for this purpose ) I get 186-188 MA from 117Vac to 119Vac and Flyback runs Very Cool, I have high Line voltage so I use a heavy duty metered Variac, the Cathode current goes higher at higher line voltages, I checked this again and edited my measurements after I removed the Seco, which is still fast and handy for this adjustment
Hope this helps
here is Current at 119Volts AC--- first picture below
2nd reading is at is at 122Volts ac and Current is 195ma at that high AC line voltage also shown below is the Heavy Duty Variac


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Last edited by wiseguy on Apr Mon 15, 2019 9:21 pm, edited 7 times in total.
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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Thu 04, 2019 9:07 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
Posts: 475
Location: New Hampshire
Off the top of my head most HOT's ran 190-210 ma.
Its usually harder to get a good dip than draw enuf. The HOT may be a tad weak
but usually you will have a width problem.
Bottom line is if the width is good & no blooming etc you are OK.

73 Zeno 8)
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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Thu 04, 2019 9:12 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Waukegan, IL
Im using an older Seco meter. The HC6 i think. On it, im only getting 110ma. And it is a new 6dq5. I havent tried adjusting anything yet. Or maybe something else is drawing too much dragging cathode current down?

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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Thu 04, 2019 9:45 pm 
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Location: madison,wisconsin
I have no issues on mine and the other CTC-11 at all, I just opened it up to share what I get for Cathode current in my chassis.
all my sweep tubes are new, so this is just to help , the lines and Moire are artifacts from the Cell phone camera

Terry


Attachments:
ctcellen.jpg
ctcellen.jpg [ 150.98 KiB | Viewed 589 times ]


Last edited by wiseguy on Apr Tue 16, 2019 11:08 am, edited 1 time in total.
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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Thu 04, 2019 10:37 pm 
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Location: madison,wisconsin
Tony (trainman )
what is your HV with contrast and Brightness turned down?
have you checked to see if the H-Lin coil is not shorted ?( the one you adjust for a Dip)
also check the H centering control for shorts and there is a Cap across it.
one other thing is the Focus coil, ( you never know)
I have my 2nd chassis out and can give you a compare Reading

Terry


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Fri 05, 2019 12:16 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Waukegan, IL
If my HV probe is accurate, im getting 24, or a tad over 24kv with brightness down. Horiz centering pot is ok. Again, who knows if my milliamp meter is correct.

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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Fri 05, 2019 8:49 am 
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Location: Lincoln City, OR
Greetings to the Forum:

Once again, I will throw in my experience with digital meters and current measurement. Don't. Most of my career I was a broadcast engineer on Mt. Wilson in So. Cal. The Rf on that hill is considerable, to say the least. I was never able to get any meaningful current reading using a digital meter.

I can't use a DMM to measure current at home either... I am often poking into fairly high power ham transmitters.... and again, the readings are variable and useless because of RF.

Digital meters measure current by inserting a low value resistance in series with the current path and measuring the voltage (millivolts) developed across it. Unfortunately, the RF field is of the same order or even more, so the current reading can change by an order of magnitude just by changing the orientation of the meter leads.

If you doubt the RF field intensity around a horizontal output tube, just bring an NE-2 lamp near the tube. You will find that it lights quite brightly. Because of this fact, you cannot measure HOT cathode current with a DMM. Not and expect to have the reading consistent with reality, anyway. Placing a capacitor across the leads does nothing; the field will radiate right into the meter case.

The only way to measure HOT cathode current is with a genuine D'Arsonval meter which is sized for the expected current (250 to 500 mA full scale). An analog meter is not affected by RF fields and will respond only to the average current.

I personally never use a DMM to measure current under any circumstances. Your mileage may vary.

Regards,

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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Fri 05, 2019 10:17 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3280
Location: Waukegan, IL
I ditched the Seco cathode current meter.

A regular VOM with the bypass capacitor gives me about a 200ma reading. How accurate the meter is, who knows. A DVM gave me .206 amps so thats says 206ma.

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Tony Pignaloni


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Sat 06, 2019 11:41 am 
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Location: madison,wisconsin
I use the Seco shown only for the H-Lin coil Dip adjustment because it has the sockets built in and I don't have to break the connection under the chassis.
if I had suspected a problem then I would be pulling out a d'arsonval type meter also for more accurate reading.

you should try the HLin-coil adjustment and see what Dip you can get as per instructions on page 16 of the Sams.
there are 2 steps

Terry


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Sun 07, 2019 12:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3280
Location: Waukegan, IL
Anyway, today i checked the cathode current in the HO tube and the regulator. adjutsted the HO current down from just over 200ma to where it dipped about 190ma. regular current was over 850 microamps(1.1ma) with brghtness down like the manual says. Not really sure where my High Voltage is. my HV meter is saying 25kv, my VTVM with its HV probe is saying 23kv.

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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Mon 15, 2019 12:02 am 
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Here is my CTC11 in operation today, still trying to figure out Camera settings
Tony can you share any pictures of your set and progress?


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Mon 15, 2019 4:22 pm 
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Joined: Aug Mon 16, 2010 6:58 pm
Posts: 219
Location: Madison, WI
Hi Terry,

That's a great looking picture on your CTC-11. The CRT must be in really good shape :)

The cathode current on my CTC-11D runs just over 190 ma.

-Clark


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 Post subject: Re: Horizontal Output cathode current RCA CTC11 too low??
PostPosted: Apr Mon 15, 2019 6:26 pm 
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Location: madison,wisconsin
Clark, K9OA wrote:
Hi Terry,

That's a great looking picture on your CTC-11. The CRT must be in really good shape :)

The cathode current on my CTC-11D runs just over 190 ma.

-Clark

that seco is used to Dip the H Coil, the meter movement is off, I measured with my Agilent and it is 188ma at 117volts AC power creeps up to 190MA with AC At 120 Volts and even higher if I set AC at 122 volts AC, I have high line voltage so I use a heavy duty Isolation transformer that is adjustable

See added images above
and again I have no problems with my set, I just opened up to test for a reference for Trainman


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