Pilot tv crt
 

Ok thinking of getting back into getting a d5-100 b@w electrostatic crt to work in a pilot tv. The hv is compatible the heater voltage is .55v I got that covered but the deflection voltages are different the pilot voltages are well over 100 v but the d5-100 are 30 40v otherwise I think it will work but can these voltages be reduced by means of resistors at the crt pin connection points. Can this actually work if this is the only obstacle. The green tube just don’t cut it.

Yeah Tim I got a NOS green tube for mine and it’s an unsatisfactory compromise. I jumped on a NOS 3KP4 on eBay and paid $300 for it but was refunded when the seller discovered the box was new but the tube was spent. Someone probably got a new tube for their 37, replaced it and put the old one in the box the new one came in. Needless to say I was pretty disappointed ��.

Oh yeah that is disappointing but the green not good hard on the eyes. Lol

Can't resist! :D

https://www.youtube.com/watch?v=rRZ-IxZ46ng

lMFAO

Does anyone know what 5847 tube is weather a 12ax7 or maybe a 12at7 don’t know what this equals.

5847 is a pentode. A 12AX7 is a dual triode.

12AX7 – High-Mu Twin Triode - generally used as audio pre-amp, very versatile.
12AT7 – Also a Mu Twin Triode, but intended for radio frequency amps, mixers & oscillators.
5847 – Pentode used mostly in IF amps

https://frank.pocnet.net/sheets/077/5/5847.pdf
https://frank.pocnet.net/sheets/049/1/12AX7A.pdf
https://frank.pocnet.net/sheets/093/1/12AT7.pdf

So are you saying this tube is a 12at7 because I don’t have the book that shows the 4 digit tube numbers camparing to an actual tube number that I can relate to.

The 5847 is a commercial version of the Western Electric 404A pentode.

12AX7 and 12AT7 are dual triodes.

Depends on the application and how it's used in the circuit, 12AT7,12AU7,12AX7, etc, all have the same 9A basing, and will SORT OF work if you mix them up, but in reality, each type was built to work in a specific type of circuit, so it's best to be sure you have the right one in the right area.

I already found out in this pilot that 5847 works for the antenna amp but not rf amp or oscillator.

What don’t make sense to me is 2 12ax7 test perfect but only one works. And I got a decent b@w picture on the pilot with the d5-100 crt but there is some biasing going on leaving the focus voltage alittle short.

You never said which pilot you had, but from what I can see, the tuner tubes MUST be 12AT7s.
Any else won't work well.
https://www.earlytelevision.org/pdf/...sams_62-16.pdf

The pilot is the 37

So the fact you got a 12AX7 to work at all, can be attributed to sheer luck, as in V1,V2,V3, it's beyond the design limitations that it's being put in, and thus not reliable, only way to go is with 12AT7s, as was intended when it was designed.

The only difference is the gain 12at7 is 70 and 12ax7 is 100 don’t know why they wouldn’t work otherwise.

Read the data sheets posted... The 2 are not compatible in RF applications, 12AX7 is an high fidelity audio amp, and 12AT7 is a radio frequency amp/osc/mixer, meaning the 12AT7 can work a much higher ranges than the X7 can, the more gain is not relevant.

Ok I got it.

First picture from the pilot 37 using the d5-100 crt.

At RF frequency minute differences in interelectrode capacitance can kill oscillation and or detune the circuit beyond adjustment range.

Probably so but I didn’t think I would even get this far with this little crt after all there are no more b&w electrostatic tubes around anymore except the green ones. I’m going to get 3 12at7 and start fresh.

Heres another picture going to need a magnifier just like the original had a magnifier still working to get it better but my cell phone camera don’t take good pics.

Getting there probably the only pilot with a 1.5 inch electrostatic crt it’s small and so was the original tube had to watch it up close and this one too and I have a small magnifying glass but don’t know if I will use it yet. As for the chassis the only thing that was changed is the hv was lowered alittle bit nothing else any changes , were made to the tube itself 2 1 meg resistors and a 500k resistor and a jumper on 2 pins.

Finally got it together and have a magnifier on the back side of the mask little small but it’s b&w not green and can actually watch it.