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Re: What are the voltages for a 5F1?

7/5/2003 2:55 PM
Jason A
Re: What are the voltages for a 5F1?
I had a friend's Victoria 5F1 in here a little while ago. The plate voltage on the 6V6 was about 402VDC. Down the line into the upper 300's for the preamp. It was an amazingly good sounding Champ. It was almost as loud/punchy as the owner's original 5E3. Side by side, they put out an impressive SPL + tone.  
7/10/2003 5:46 PM
bob p
here are some voltages that i measured on original fender PT iron with no load:  
1956 Champ:  
110 primary  
240-0-240 secondary  
1959 champ:  
110 -> 302-0-302  
1955 Princeton  
110 -> 325-0-324  
As you can see, there's quite a bit of variability among the early/late tweed champs, and a very significant difference between the champs/princetons of the same era.
7/10/2003 6:02 PM
Bruce /Mission Amps

Right and now stick those PTs on a Variac and measure the voltages at 110vac, 115vac, 117vac 120vac and what I get frequently, 124vac.  
7/12/2003 8:30 AM
What is that on a 5y3?
What would those voltages (300-325vac) produce in B+ through a 5Y3?
7/12/2003 4:42 PM
Bruce /Mission Amps

It completely depends on the load through the rectifier.  
A NOS 5Y3GT is nice and soft so there is a big drop when 60ma to 80ma flows through it.  
With no load, the power supply B+ into a decent +10uF cap will probably charge up to about 425vdc@300vac and about 460vdc@325vac.  
Under an average solid load like two semi hot power tubes with two or three preamp tubes, that number would be quite a bit less... maybe 330vdc@300vac and 360vdc@325vac.  
Again, it really depends on the current load through the 5Y3GT.  
7/19/2003 9:57 PM
bob p Re: What are the voltages for a 5F1?
"now stick those PTs on a Variac and measure the voltages at 110vac, 115vac, 117vac 120vac and what I get frequently, 124vac."
er, Bruce, I had to use a variac to get the primary voltage down to 110 in the first place, so i'm not quite sure that i get your point.  
when i dialed down to get those measurements, i did the variable input voltage thing that you recommended. i have the results in a spreadsheet, but i didn't bother to post them because they didn't answer the question asked in the original post, and because anybody could calculate them by calculating the turns ratio from the information that i supplied, and then chugging through a little math.  
if you were hinting at the huge differences that a user will get when plugging vintage iron into today's modern wall voltages, i couldn't agree with you more. the reason for my post, though, was to answer the original question about what the secondary voltages should be for somebody trying to build a tweed champ replica. the information supplied should make it easy enough for somebody to determine what kind of iron they'll need if they're correcting for today's primary voltages.  
7/20/2003 6:41 PM
Bruce/ MissionAmps

Yup, it was a veiled comment about how those old PTs can kill a cheaply made modern 6V6... because it forces the secondary vac up so much higher.  
With modern filter caps and a stiff rectifier, the B+ can be brutal.  
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