Re: [Amps] Looking for Alpha 87A expertise

[Jim <jimw7ry@gmail.com>]

Doug...

How fast is a PIN diode?  How fast is a 1N4007 in an Alpha 87? If you 
have not measured their speed, how can you make that statement?

Thanks
73
Jim W7RY

On 3/14/2021 7:59 PM, Douglas L via Amps wrote:
> I have doubts about replacing those PIN diodes with 1N4007’s. The 1N4007’s 
> don’t switch quickly enough to substitute for a PIN.
>
> 73,
> Doug/WA1TUT
>
>
> > On Mar 14, 2021, at 3:16 PM, Steve Thompson <g8gsq72@gmail.com> wrote:
> >
> > 
> > > 2.  Is a drop from 900V open-circuit to 730V typical when
> > > disconnecting/reconnecting the "R" bias lead at the HV board?  I'm wondering
> > > if I have another leaky PIN diode or cap to ground that is loading it down.
> > > It doesn't take much to load the bias supply given that it inherently has
> > > 880k of series resistance.
> > I don't know the 87A circuits, but assuming the 900V/880k supply is loaded with 
> > a reverse biassed diode with 3.9M across it, the current in the 3.9M will drop 
> > the voltage to a calculated 734V - close enough to what you're seeing so I'd 
> > guess it's ok.
> >
> > I'd hazard a guess that the 3.9M resistor(s) are there to try and avoid 
> > problems from static build up.
> >
> > Sorry, can't help with anything else.
> >
> > Steve G8GSQ
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps