F6 Amplifier

[triode_al]

I'm talking about possible oscillations

if you don't have CRO , use this (attached) on amp output

if you see it lit , trouble is there

your smarter than my Papa!
It also allows you see thing the scope doesn't

 

[Zen Mod]

naah

moi inventing boiled water

 

[palstanturhin]

Hey!!!

OK... I am going to make this one.

I have the transformers already at the Finnish customs service.
Will get them from there on next monday.
And, I will (already have) design my own PCB.

Anyways,
a simple question:

2SK1058?
(Which would be a nice low capacitance load for the JT123??? Or what?)
Any objections?

 

[Zen Mod]

why not?

even if I prefer more greater xconductance of IRFP critters , in this case

 

[buzzforb]

I tried lay fets in first version. No degeneration on bottom and .05 on top, if that. If you can match, put higher gain device below and use no source resistor on either. In Europe I would try Lundahl like Rowland uses in his amps

 

[Variac]

Make a CLC power supply! Big inductors!

Damn and I have three 100m spools of 1.5mm solid core wire...

 

[flocchini]

Make a CLC power supply! Big inductors!

I have four Jantzen Audio 15mH 15 AWG P-Core Inductors - Would these be suitable?

Thanks

Bob

 

[Zen Mod]

if they're good for Iq (DC!) , then perfect

 

[flocchini]

Looks like they are used for woofer crossovers

Specifications: • Tolerance: ± 5.0% • Inductance: 15.00 mH • Wire gauge: 15 AWG • DC resistance: 0.42 Ohms • Dimensions: 2.40" x 1.20" • Power handling: 400 watts RMS.

So if Voltage = 24V and I = 1.5A Power (VI) through should be 36W

 

[Rush]

Looks like they are used for woofer crossovers

Specifications: • Tolerance: ± 5.0% • Inductance: 15.00 mH • Wire gauge: 15 AWG • DC resistance: 0.42 Ohms • Dimensions: 2.40" x 1.20" • Power handling: 400 watts RMS.

So if Voltage = 24V and I = 1.5A Power (VI) through should be 36W

I=V/R
I=1.5 A
R=.42 ohms
V= voltage drop across coil
V=I*R = 1.5*.42 =.63 V
V*I= P
P=.63*1.5 = .945 watts

Rush

 

[Zen Mod]

nope

Jantzen Audio 15mH 15 AWG P-Core Inductor Crossover Coil

ferrite core Iznogud for DC

 

[flocchini]

Thanks Rush and Zen Mod

Have to look for some Erse 14 guage
I think NP recommended 2mH in one of his articles - cant find it now.

Something like

ERSE-XQ

or

Copper Foil Inductor Coils | Foil Q | ERSE ?

Thanks

Bob

 

[Zen Mod]

air core is good

either that or I , EI, E iron standard cores

no toroids , no powder

 

[flocchini]

thanks again

 

[marconi118]

any need of ntc temp compensation (like F5) with IRFP140?

 

[Zen Mod]

where is Papa's schematic with IRFP ?

 

[6L6]

Change Z1, Z2 to 9.1V

 

[Zen Mod]

so , R1 and R2 are there , for peaceful sleep .

 

[marconi118]

How is the temp compensation done without NTC?

will the amp drift to more idle current when hot?

 

[Zen Mod]

go to Papa's FW site and download all pdfs , and read

source resistors are there , to counteract mosfet's tempco