6X5 rectifier

[Toxophilite]

I have a PT that uses one of these with a pair of 6V6s in parallel and a pair of 12ax7s
I'm planning on swapping it all over to a more convenient chassis and building a 5F11 vibrolux


I've read that the 6X5 is less than ideal and didn't provide a lot of current


I could use solid state rectification but for this build I'd rather stick with a tube rectifier if i can


Any info on/experience with the 6X5?

[jjasilli]

At only 70mA it looks to be inadequate for a pair of 6V6's,  Also it wants to see a 4uF cap.

[billcreller]

Some of the '40s low priced amps had PTs with 70 MA for two 6V6s anyway....    Maybe the 6X5 was cheaper than a 5Y3 back then also (?)

[sluckey]

An EZ81 (6V filament) would work OK with a pair of 6V6s. A pair of SS diodes and a 100Ω to 250Ω resistor would give you that tube feel. Weber sells a SS copper-cap rectifier with built-in resistor in a tube base module.

     http://www.webervst.com/ccap.html

[Toxophilite]

Hey I forgot about the 6CA4, that's a good idea and I have a few



Also Solid state with a dropping resistor would be a good idea too


THanks!

[trobbins]

The PT sounds like it had a 2A 6V heater rating?  6V4G would be the next increment up if you had one, and didn't want to go over 2A.

[kagliostro]

Talking about 6x5

I don't know if this is a typo, but I read 40uF as first capacitor



and in other datasheet 4uF (???)

http://www.tubezone.net/pdf/6x5gt.pdf

http://www.mif.pg.gda.pl/homepages/frank/sheets/121/6/6X5.pdf

As far as I can know, I can increase the tube voltage handle using a pair of SS diodes in series, but .... there is a trick also to increase the

max first capacitor value ?

I've some 6x5 (may be 6x5gt) and I would like to use it at the best

Franco

[jjasilli]

Both tubezone & Frank's say 4uF.


I think the simplest trick for more filtering is to follow the 4uF cap with a small value dropping resistor, then a a larger cap to feed the power tubes.  That way the 4uF cap becomes a "pre-filter" to the 1st stage, and keeps the 6X5 happy.


A diode or resistor might work right after the 6X5 , basically substituting for an inductive input, I guess. 

[kagliostro]

Thanks JJasilli

Franco

[trobbins]

The transformer primary and secondary winding resistances play a part too.  Perhaps best to try using PSUD2 to better identify what the steady state peak plate current will be.

[Toxophilite]

To further confuse things
On this amp a 6V6 pushpull unit
The main filter caps are 10, 30, 40, (uf) with the 10uf being the first stop after the rectifier

[jjasilli]

Manufacturers are known to cheat with cap values after rectifier tubes.  Even so, 10uF is still small and risks shortening the life of the rectifier tube.

[terminalgs]

FWIW, Webcor used 6X5's in lots of tape recorders with 6V6s and 6K6s, usually less than 300V B+.  They always put 20mfd or 25mfd caps as the first reservoir cap. 


As for your 5F11 build up.  Check the B+.  If you don't have 330-340VDC with your donor PT, the 6X5/PT is not a good candidate.

[Toxophilite]

Should I be measuring that right at the rectifier? (which isn't currently hooked up to a filter cap?)
Or should I hook up at cap to get a better idea?

[sluckey]

Should I be measuring that right at the rectifier? (which isn't currently hooked up to a filter cap?)
Or should I hook up at cap to get a better idea?

Always put a cap on it.

[trobbins]

Perhaps if you measure the HT winding voltage and the primary and secondary HT winding resistances, then that would be a start to working out what DC voltage you would get , and what filter capacitance can be used.

[PRR]

> say 4uF.

That is an Application EXAMPLE, *not* a Maximum Rating.

There's fine print about other cap values, if you read all which was written on the sheet.