[Johnson] Looking for resources and possibly some help . . .
Richard Solomon
w1ksz at outlook.com
Sun May 19 01:09:58 EDT 2019
That's why one should use the now un-used filament winding
to buck the AC Line.
When I SS Collins 516F-2's, I use both filaments to buck the now
higher AC Line Voltage down to something closer to the Collins
design.
73, Dick, W1KSZ
Sent from Outlook<http://aka.ms/weboutlook>
________________________________
From: johnson-bounces at mailman.qth.net <johnson-bounces at mailman.qth.net> on behalf of Richard Knoppow <1oldlens1 at ix.netcom.com>
Sent: Saturday, May 18, 2019 8:25 PM
To: johnson at mailman.qth.net
Subject: Re: [Johnson] Looking for resources and possibly some help . . .
I am a little skeptical about replacing vacuum tube
rectifiers with silicon diodes. Mainly because of the much lower
voltage drop of the diodes. Vacuum tubes drop tens of volts while
a diode drops perhaps 1.5V. Not always a problem but makes me
worry about the voltage limits of components and tube dissipation.
Replacing mercury or gas rectifiers is not so bad because
they all have a fixed drop of around 15 volts. Since they are
usually used for high voltages there is no drawback in using a
series of diodes to add up to the tube drop. A series resistor
and diode will not duplicate a vacuum rectifier because the tube
internal resistance is not linear with current.
I used to be concerned with the nearly instant application of
DC from diodes but found that vacuum tubes apply output voltage
very quickly even without the filaments being fully heated. Look
at anything with a voltage regulator tube in it, usually they
will begin to glow as soon as the AC is applied.
I do agree that if you use diodes they should go on the
socket pins and the socket covered over with something.
On 5/18/2019 7:27 PM, qrv at kd4e.com wrote:
> Will do, thanks!
>
>> Check the underside, the Rectifiers could be soldered to the
>> tube pins.
>>
>> 73, Dick, W1KSZ
>
--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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