NOS JAN-5998 TUNG-SOL -- FTR impedence -- How can use it ???

[kagliostro]

A friend give me as a present

2 x NOS JAN-5998 TUNG-SOL



and

3 x NOS FTR impedences

for the impedance I am not sure if I can use it in some way

about the 5998 at the moment i find only HiFi DIY projects but I'm not interested in HiFi

have you suggestions about it ?

can I put in parallel the two triodes (of one tube) and use the Champ 5F1 schematic as a base ?

if a Champ version is a good idea which components I must use ( values for: B+ voltage - grid and cathode resistor - cathode cap - OT primary impedance)
in an HiFi project I've seen the two diodes of one tube paralleled and used with 307v on plate and an OT with 2500ohm primary

or do you think there are better way and project for the 5998 ?

MANY THANKS for any suggestion

Kagliostro

[eleventeen]

Those tubes sell for between $35 and $50 each. I myself am skeptical of building a bzarre something just because you have some weird tubes. For whatever those tubes can do for you, I'd prefer to buy a great power & output tranny and run 6L6's or 6V6's in a generally conventional, proven circuit. But that's me.

[PRR]

5998 hi-fi amp - 275V plate-cathode, -40V grid bias, 50mA idle per tube, 8K-10K load: 10 Watts output, damping factor of 3. Need 40V peak swing per grid.

Roughly: a "sane" push-pull 6V6 chassis (not an over-volted Fender), but you will need about twice the grid swing which may require heavy re-design of the driver.

A fairly mellow amp. Not rock-n-roll.

The chokes would be suitable for power filtering. Use 40uFd, a 2Hy choke, another 40uFd, and feed your PT {edit: OT} CT from here. Plenty clean.

[kagliostro]

Thanks to both friends for reply

so I'll not use the tube for a guitar amp  

for PRR

for the impedance I am not sure if I can use it in some way

thanks for indications

also now my confusion is because in the impedance they print

8V. RMS

considering that, can be confirmed I can use for B+ filtering ?

also need a bit more explanation about

and feed your PT CT from here

sorry  , not able to understand well the relation with CT  

Thanks in advance

Kagliostro

[PRR]

ME> feed your PT CT from here

SORRY!! Too much coffee. I mean to feed your OUTPUT transformer from the second cap in the C-L-C filter.

> 8V. RMS

This is the maximum AC voltage. In a C-L-C filter with a good first C, the AC ripple on the first cap is "small". For 40uFd, 2H, 40uFd, 250V 100mA load, it is about 5V RMS.

BUT WAIT!! It also says 230 C.P.S. It may not be rated for 50Hz/60Hz operation! It is more likely part of a speech-filter, to block low tones in a telephone system and improve speech clarity. OR to insert DC power onto a phone line without loading-down the audio. Ah, and the 0.13A D.C. rating is roughly the maximum DC current in a large phone line.

[kagliostro]

Many thanks PRR

I mean to feed your OUTPUT transformer from the second cap in the C-L-C filter

oh ..... OK, now I understand

230 C.P.S. It may not be rated for 50Hz/60Hz operation

we are speaking about an impedance in the B+ branch

and you are putting the index in the 230 C.P.S. that are very far from the 50Hz of the line

is the problem in the residual ripple (the 5v you explained me before) ?

 

no ..... my knowledge is too poor to understand that

in my mind I see only a wire crossed by DC

what will change with a higher edit: LOWER (50Hz) frequency ?

the impedance will not be 2 HYS ?

the impedance will became very hot and can blow or explode ???

Thanks for any further explanation about

Kagliostro

[sluckey]

Read this...  http://www.allaboutcircuits.com/vol_2/chpt_3/2.html

You have a 2 henry inductor (choke). That value is determined by physical parameters at build time and is called inductance (L). It will always be 2H regardless of how it is used.

Inductors have another property that is very important. It's called inductive reactance (kinda like resistance). Inductive Reactance opposes current flow in an AC circuit, just as resistance opposes current flow in a DC circuit. But, inductive reactance is frequency dependant. Inductive Reactance equals 2 times PI times frequency times inductance (in henrys). Or, X_L=2πFL.  (Sorry if my PI symbol looks funny!)

So, that 2H choke would have 754Ω reactance to 60Hz, and it would have 2890Ω reactance at 230Hz.

Since the choke was designed around a frequency of 230Hz, the wire may not be heavy enough to carry the rated current if operated at 60Hz. (I'm not certain of this). You can always try it and see how effective it is, but I'm inclined to use a choke designed for the frequency it will be used for.

in my mind I see only a wire crossed by DC

Ah, but it's not dc yet! A full wave rectifier outputs a unipolar pulsating AC waveform that's twice the frequency of the AC input. It's the job of the filter caps and choke to smooth that out to a reasonable imitation of pure DC.

[PRR]

> wire may not be heavy enough to carry the rated current if operated at 60Hz. (I'm not certain of this).

No. The maximum useful AC (ripple) goes down as frequency goes down. If it "chokes" with up to 8V AC at 230 Hz, the maximum 100Hz ripple is 3.4V AC. If the AC is larger the iron saturates and it does not "choke", the ripple passes through.

Sorry. This is probably not intended to be a B+ power filter, and probably would not be a good power filter. Maybe a tone-control? But the impedance is more suited for transistors than tubes.

[kagliostro]

Many Many thanks for very interesting and useful infos

Kagliostro