[Heathkit] DX-40 question

Fri, 26 Dec 2003 12:05:21 -0800

How about powering it from the filament supply via a diode and filter.
You could use 2 diodes in a voltage doubler circuit if required?

Ed Richards K6UUZ

On Fri, 26 Dec 2003 09:36:43 -0600 "Ed Worst" <[email protected]> writes:
> Hello Mark,
> 
> Did you say you just did a solid state conversion for a VF-1?  
> That's on my
> winter to-do list.  Do you have an article you can point me to for a
> reference?  I have an article from Dec 72 QST that I was going to 
> use, but
> if you have something newer it would probably be a better mod.
> 
> I have a DX-35, and in the manual it says, "Pin 4 supplies B+ 
> voltage
> through a 20k 10w resistor.  This provides approximately 250 volts 
> at 20
> milliamperes." {for a VF-1}
> 
> So that means there's a 400v (20k x .02A) drop across the 20k / 10w
> resistor.  That would put the 6146 plate voltage at 650v (250v at 
> pin 4 plus
> 400v across the dropping resistor).
> 
> If you're planning on powering the solid state VF-1 from that, WATCH 
> OUT!
> That's a 650 volt source with a 20k impedance.  I don't know what 
> voltage
> you need for the VF-1, but the voltage you will get from pin 4 is:  
> 650v -
> (20,000 x I), where I is the current in Amps drawn by your modified 
> VF-1.
> 
> If your mod is from that Dec 72 article, you'll be OK because the 
> mod
> includes two additional 15k / 5w dropping resistors and a 20v zener.
> 
> Hope this helps, and if you have any questions send me an email.  As 
> I said,
> the VF-1 mod has been on my list for years, and ... this is the 
> year.
> 
> 73,
> ed - k9ew
> 
> ----- Original Message -----
> From: <[email protected]>
> To: <[email protected]>; <[email protected]>
> Sent: Friday, December 26, 2003 8:12 AM
> Subject: [Heathkit] DX-40 question
> 
> 
> >
> >   Does anyone know the typical no-load/load plate
> > voltage is on the 6146?  I have a schematic, but I can't
> > read the printing, looks like 380 volts no load, and
> > this seems low.
> >  What I really want to do is determine the rated voltage
> > at the acc. socket pin 4. I converted a couple of VF-1's to
> > all solid state for a friend and I need to make a small
> > change in the DX-40.
> >
> >
> >
> > Mark  WB8JKR
> >
> > _______________________________________________
> > List Administrator: Duane Fischer, W8DBF
> > ** For Assistance: [email protected] **
> > $$ See the vintage area on the HCI web site - http://www.w9wze.org 
> $$
> > Heathkit mailing list
> > [email protected]
> > http://mailman.qth.net/mailman/listinfo/heathkit
> 
> _______________________________________________
> List Administrator: Duane Fischer, W8DBF        
> ** For Assistance: [email protected] **         
> $$ See the vintage area on the HCI web site - http://www.w9wze.org 
> $$ 
> Heathkit mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/heathkit
> 