[R-390] Parts from Germany

[sigmapert]

Reply to concerns of Chuck Rippel regarding a large amount of heat generated by the 3TF7
replacement.

My 3TF7 replacement is based on a SWITCHING voltage regulator (12.6 Volts). Power
dissipation is less than 1 Watt. Therefore the device remains cool.

BTW, I've built a similar regulator (6.3 Volts) for the hard to find 4H4C ballast tube as
found e.g. in the National NC-300, NC-303, NC-400, HRO-60, and in the Hallicrafters SX-88.

http://schmid-mainz.de/4H4C/4H4C_Replacement_const-6.3V+Box.jpg
http://schmid-mainz.de/4H4C/4H4C_Replacement_const-volt_AC-DC_Relationship.JPG

This is a totally different regulator than the constant current regulator published in ER
264 that gets really hot.

http://schmid-mainz.de/4H4C/4H4C_Replacement_const-cur_ER264.pdf

SigmaPert - DH3PJ

sigmapert at gmx.de

> I've seen the caps, they are nice but look a bit out of place.  That said, that chassis
> is under the mother chassis and is out of sight.

> I'd be careful about the solid state ballast replacement.  Am worried about the small
> containers ability to dissipate the amount of heat that's generated.  I built one that
> was current regulated and used a Hammond aluminum project box to heat sink the
> components.  It ran warm to the touch.  There are 2 tube filaments whose voltage (actually, current) are regulated.

> I have one here along with the balun the owner wants to try on his competed radio.  We'll see how hot it runs.

> Chuck Rippel
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