Questions about building a Fender Champ Amp(5F1)

[sir_modulus]

I have a transformer at home, thats a 300-0-300 (so i can get 600 and 300V) I want to build a fender Champ Amp, and was wondering if this tranny was good. What Hammond trannie could be used for a replacement. Also for the output trannie, what is the hammond equivilent. I'm building the 5F1 (schem is here http://www1.korksoft.com/~schem/fenderamps/) and am using stock tubes (6V6GT, 5Y3GT, 12AX7A). Thanks.

P.S. When they say a trannie is 300-0-300, thats with just a multimeter to the leads, so you get inductive kickback also right?

[cd]

Don't bother with the Hammond replacements, the genuine Fender ones are easily available and cheaper.

[sir_modulus]

Well, the thing about that is, i can get the output trannie, but in my city, we have Active electronics, which is useless for normal components, but, carries every Hammond tranny  and available, and it's easier to get stuff, as it's in the city and i get 20% off.

[Eric H]

I have a transformer at home, thats a 300-0-300 (so i can get 600 and 300V) I want to build a fender Champ Amp, and was wondering if this tranny was good. What Hammond trannie could be used for a replacement. Also for the output trannie, what is the hammond equivilent. I'm building the 5F1 (schem is here http://www1.korksoft.com/~schem/fenderamps/) and am using stock tubes (6V6GT, 5Y3GT, 12AX7A). Thanks.

P.S. When they say a trannie is 300-0-300, thats with just a multimeter to the leads, so you get inductive kickback also right?

What else do you know about the PT? (VA rating, 6v winding etc.)
A Hammond 125E works well in champ-type circuits --and is inexpensive.

-Eric

[sir_modulus]

Nm, the trannie i have is crap. It has some secondaries, but it is in real bad cond. Whats the hammond replacement. Thnx.

[sir_modulus]

Anyone have any ideas?

[Ballz]

Yep, I have some ideas. This is actually the 3rd time I sit down to type some kind of reply, so I´ve been thinking - not so much about the transformers, but how to word my reply...

From your posts/replies, I have to assume that you don´t have much time/patience  :lol:  - and I also assume that your tube amp experience is limited.

You have 3 options, as I see it - use the 300-0-300 trannie you have but don´t trust, order a Champ or Deluxe replacement tranny, or get a Hammond.

You are dead set on Hammond for some reason....so...
:lol:

here we go, I will do the footwork for you:

Since you will use the 5Y3GT rectifier, you will need a 5V filament winding on the transformer.

You will need a 6,3V winding too, for the heaters of the 12AX7 and the 6V6.

The capacity of these windings is not very critical, these tubes don´t draw much heater current. Data can be found easily, but here´s the rundown for the impatient:

6,3V winding: 12AX7 heater 0,3A, 6V6 heater 0,45A = 1A is good enuff, 2 is ample if you want to expand the amp.

5V winding:  5Y3GT draws 2,0A, and you will want just a little bit more.

Primary: I don´t know your wall voltage, so I suggest you look at the 300 series, which has both 115 and 230V primaries.

Secondary winding: You just chose the 5Y3GT rectifier. This rectifier drops the final rectified voltage by about 50V, BTW, you have to calculate on this fact.

Furthermore, you are going to need a center-tapped secondary.

This should have limited your choices down to about ten from Hammonds list.  :lol:

Well, what about the secondary voltage?

Well, you will need to have 350V or just below for B+ rail voltage to make make the 6V6 work out properly....but that´s the final "product" and there are some fishy things going on in the rectifier department that need to be calculated ....and the DC current handling capability should be somewhere between 100 and 200mA (in case you want to expand the amp later).... wouldn´t it be easier to grab a Fender replacement?  

In any case, you should be down to about 4 choices by now.

I´m afraid I can´t help you with the transformers exact secondary voltage, since I am not too familiar with tube rectifiers, so I don´t want to risk giving crappy advice on that. There will be someone else chiming in on that one, if you give them a couple of hours. :lol:

Edit (afterthought): Why not skip the 5Y3GT? You´d save money on the tranny (1 winding less), save even more on the tube and socket, you get less heat, and a diode bridge is a lot cheaper and easier to calc with. Tube recto is overkill in a single-ended amp anyway, IMHO, since there will be no noticeable sag effect (which is why tube rectos are preferred) in this type of amp.

Secondary AC Volts x 1,4 = secondary DC Volts (useable formula if you use a diode bridge and some reasonable smoothing caps)

A 250V secondary (not even centertapped) perhaps might do the trick?

Cheers /Richard

Oh, yes - the Hammond 300 list:
http://www.hammondmfg.com/300series.htm