"AA5JJ" wrote

1N1239 Solid State replacement for 5R4 tube

Can anyone tell me exactly what these replacement plugs have in them and
a
schmatic so I can make some for myself I have the plugs to use but need
the
rest of the info to bulid them.


****Wayne,your nominated reply email address is invalid,hence the reply
here.

There are two 1N4007 silicon diodes in an Octal base.Pin 4 is diode 1
Anode,pin 6 is diode 2 Anode and the two cathodes connect to pin 8.You
will probably have to include a power resistor of about 47 Ohms @ 10
Watts to drop the output voltage to the same value as would have been
provided by the vacuum tube rectifier.
Cheers from down under,Brian Goldsmith.

Brian Goldsmith wrote:


There are two 1N4007 silicon diodes in an Octal base.Pin 4 is diode 1
Anode,pin 6 is diode 2 Anode and the two cathodes connect to pin 8.You
will probably have to include a power resistor of about 47 Ohms @ 10
Watts to drop the output voltage to the same value as would have been
provided by the vacuum tube rectifier.
Cheers from down under,Brian Goldsmith.


Voltage drop for a 5R4 is on the order of 67 volts at 250ma. A 47 ohm
resistor will only drop 12 volts in this example.

-Bill

A 5R4GYB is rated at 3100V PRV. You would need 3 1N4007's in series
in each leg (total of 6) to match the peak reverse voltage rating.

I have solid-stated the 5R4 in a Hallicrafters HT32B without
using a series resistor to drop the HV back down to that
produced by the 5R4. That's OK in this application,
because the 5R4 is only used for the plate supply for the 6146's.
Using the higher plate voltage, I just readjusted the grid bias
for the same 40 mA resting current.

73,
Ed K4PF

"Edward Knobloch" wrote

A 5R4GYB is rated at 3100V PRV. You would need 3 1N4007's in series
in each leg (total of 6) to match the peak reverse voltage rating.

*** You are correct,however the original poster stated he wanted a
replacement for a 5R4.This tube has a maximum plate Voltage of 750 RMS
per plate for which a 1N4007 will suffice.

Brian Goldsmith.

Brian Goldsmith wrote:

snip however the original poster stated he wanted a
replacement for a 5R4.This tube has a maximum plate Voltage of 750 RMS
per plate for which a 1N4007 will suffice.


The 5R4 has a maximum piv voltage of 2800 volts,
so you would still need 3 1N4007's in series
in each leg for equivalent safety factor.

The rated max supply voltage of 750V rms per plate means that
you should not use a transformer higher than
1500V rms center tapped in a full wave single phase
rectifier circuit using a 5R4.

The designers expected switching transients
when the current is interrupted in the HV transformer
and HV choke, and therefore included a max
supply voltage for guidance.

73,
Ed K4PF

In article , Edward Knobloch
writes:

The 5R4 has a maximum piv voltage of 2800 volts,
so you would still need 3 1N4007's in series
in each leg for equivalent safety factor.

Absolutely correct.

The rated max supply voltage of 750V rms per plate means that
you should not use a transformer higher than
1500V rms center tapped in a full wave single phase
rectifier circuit using a 5R4.

The 750 volt rating is for capacitor input. With choke input you can go a bit
higher.

The designers expected switching transients
when the current is interrupted in the HV transformer
and HV choke, and therefore included a max
supply voltage for guidance.

Even with no transients, the peak voltages that the diodes have to withstand
are quite high, compared to the RMS transformer voltages. Here's why:

First off, the voltages in the transformer catalogs and tube manuals are RMS
values, not peak values. 750 volts RMS equates to 1060 volts peak with sine
waves. So under perfect conditions a 750-0-750 (1500VCT) transformer with
fullwave center tap rectifier and capacitor input filter can have voltage
output of 1060 volts.

But there's more! In our 750-0-750 example, each transformer HV lead goes from
1060 volts (peak) positive to 1060 volts negative with respect to the center
tap. So each diode is subjected to as much as 2120 volts when it is in the
nonconducting (inverse) state. So you need *at least* three 1N4007s to replace
one side of a 5R4. Four diodes won't hurt a thing.

The tube manuals I have show voltages higher than 750 for capacitor input, but
they are for the 5R4GYA.

In any event please use at least three and preferably four 1N4007s or
equivalents in a 5R4 replacement. Plate transformers and filter chokes can be
expensive and hard to replace.

73 de Jim, N2EY

In article , Edward Knobloch
writes:

The 5R4 has a maximum piv voltage of 2800 volts,
so you would still need 3 1N4007's in series
in each leg for equivalent safety factor.

Absolutely correct.

The rated max supply voltage of 750V rms per plate means that
you should not use a transformer higher than
1500V rms center tapped in a full wave single phase
rectifier circuit using a 5R4.

The 750 volt rating is for capacitor input. With choke input you can go a bit
higher.

The designers expected switching transients
when the current is interrupted in the HV transformer
and HV choke, and therefore included a max
supply voltage for guidance.

Even with no transients, the peak voltages that the diodes have to withstand
are quite high, compared to the RMS transformer voltages. Here's why:

First off, the voltages in the transformer catalogs and tube manuals are RMS
values, not peak values. 750 volts RMS equates to 1060 volts peak with sine
waves. So under perfect conditions a 750-0-750 (1500VCT) transformer with
fullwave center tap rectifier and capacitor input filter can have voltage
output of 1060 volts.

But there's more! In our 750-0-750 example, each transformer HV lead goes from
1060 volts (peak) positive to 1060 volts negative with respect to the center
tap. So each diode is subjected to as much as 2120 volts when it is in the
nonconducting (inverse) state. So you need *at least* three 1N4007s to replace
one side of a 5R4. Four diodes won't hurt a thing.

The tube manuals I have show voltages higher than 750 for capacitor input, but
they are for the 5R4GYA.

In any event please use at least three and preferably four 1N4007s or
equivalents in a 5R4 replacement. Plate transformers and filter chokes can be
expensive and hard to replace.

73 de Jim, N2EY

Brian Goldsmith wrote:

snip however the original poster stated he wanted a
replacement for a 5R4.This tube has a maximum plate Voltage of 750 RMS
per plate for which a 1N4007 will suffice.


The 5R4 has a maximum piv voltage of 2800 volts,
so you would still need 3 1N4007's in series
in each leg for equivalent safety factor.

The rated max supply voltage of 750V rms per plate means that
you should not use a transformer higher than
1500V rms center tapped in a full wave single phase
rectifier circuit using a 5R4.

The designers expected switching transients
when the current is interrupted in the HV transformer
and HV choke, and therefore included a max
supply voltage for guidance.

73,
Ed K4PF

"Edward Knobloch" wrote

A 5R4GYB is rated at 3100V PRV. You would need 3 1N4007's in series
in each leg (total of 6) to match the peak reverse voltage rating.

*** You are correct,however the original poster stated he wanted a
replacement for a 5R4.This tube has a maximum plate Voltage of 750 RMS
per plate for which a 1N4007 will suffice.

Brian Goldsmith.

A 5R4GYB is rated at 3100V PRV. You would need 3 1N4007's in series
in each leg (total of 6) to match the peak reverse voltage rating.

I have solid-stated the 5R4 in a Hallicrafters HT32B without
using a series resistor to drop the HV back down to that
produced by the 5R4. That's OK in this application,
because the 5R4 is only used for the plate supply for the 6146's.
Using the higher plate voltage, I just readjusted the grid bias
for the same 40 mA resting current.

73,
Ed K4PF