14rp4 substitute

[timmy]

Does anyone have an substitute book for crt tubes. I have a 14rp4a for an admiral and I would like the reading to be higher so I may be looking for a sub. Would a 14atp4 work or what would the differences be.

[tom.j.fla]

These are the CRTs that will sub with no mods needing to be done,14RP4,14NP4,14NP4A and 14SP4. All the best,Tom.J

[kvflyer]

The 16" version of the set, 26R12 I think, used the same series of tubes, 16RP4, 16TP4 if memory serves me. Try "Googling" those numbers and compare the tubes.

[kvflyer]

Originally Posted by kvflyer

The 16" version of the set, 26R12 I think, used the same series of tubes, 16RP4, 16TP4 if memory serves me. Try "Googling" those numbers and compare the tubes.

Check the info above, it arrived whilst I was typing.

[timmy]

Originally Posted by tom.j.fla

These are the CRTs that will sub with no mods needing to be done,14RP4,14NP4,14NP4A and 14SP4. All the best,Tom.J

Any chance a 14atp4 would work ?

[tom.j.fla]

Short answer NO, the 14ATP4 has no sub. Sorry, Tom.J

[timmy]

Originally Posted by tom.j.fla

Short answer NO, the 14ATP4 has no sub. Sorry, Tom.J

Hmm, I wonder what is so different , it looks the same along with the gun.

[dieseljeep]

Originally Posted by timmy

Hmm, I wonder what is so different , it looks the same along with the gun.

The difference is the the heater current and voltage. 8.4 volts@ 450ma.
These tubes were used in RCA's and Westinghouses with 450 heater string, 17DQ6, 17AX4 etc.
A 50 ohm 2 watt resistor in parallel with the 14at heater would work OK.

[timmy]

Originally Posted by dieseljeep

The difference is the the heater current and voltage. 8.4 volts@ 450ma.
These tubes were used in RCA's and Westinghouses with 450 heater string, 17DQ6, 17AX4 etc.
A 50 ohm 2 watt resistor in parallel with the 14at heater would work OK.

The 14atp4 I wanted to use in place of the 14rp4 and I'm not sure what your saying with the resistor. Are you saying to put in the 17ax4 and 17dq6 in place of the 12dq6 and 12ax4 and then this raises the heater voltage and use a 50 ohm 2 watt resistor between the heater. I'm probably way off here thinking the 17, volt tubes would take more .im missing something on how to get more voltage for the crt . If the physical size is the same as the 14rp4 I could just use a separate heater transformer for the 14atp4 , that should work.

[tom.j.fla]

Timmy, dieseljeep is saying that the heater current of the 14ATP4 is different than the crt you have in your set. If you do what dj says you put the 50 ohm 2 to 3 watt resistor across the 14ATP4 heater only, that combo makes the current draw of the crt resistor pair 600 ma. to match the current draw of the rest of the tubes in the set. If I did the math right a 24 ohm 3 watt resistor will be just right for the crt shunt resistor. Tom.J

[timmy]

Originally Posted by tom.j.fla

Timmy, dieseljeep is saying that the heater current of the 14ATP4 is different than the crt you have in your set. If you do what dj says you put the 50 ohm 2 to 3 watt resistor across the 14ATP4 heater only, that combo makes the current draw of the crt resistor pair 600 ma. to match the current draw of the rest of the tubes in the set. If I did the math right a 24 ohm 3 watt resistor will be just right for the crt shunt resistor. Tom.J

So what is being said is I would be able to use the 14atp4 provided I put the resistor across the heater. I looked at the size of both tubes and if I didn't miss anything it looks the same maybe a 1/6 inch different which I should be able to make that up if that's the case. The heater voltage would be enough 6.3 v aside from the 8 volts the 14atp4 requires.

[jr_tech]

What is the model number of the set? Does it have series string heaters or is there a power transformer supplying 6.3 volts to the tube heaters?

jr

[timmy]

The chassis number is 14yp3c . I would just like to know if that tube will fit and I can use it.

[jr_tech]

Ahhh! series string, so the 14ATP4 with heater bypassed with the correct resistor will get the proper 8.4 volts.

jr

[tom.j.fla]

If the crt you have will fit yes you can use it as long as you use the before mentioned shunt resistor. Make sure you make note of the change and note the added resistor for the crt heater in your notes for future use. FYI you have to take in account not only the heater voltage but also the heater current as well, a mismatch in current is not so good for the tube(s). Tom.J