This 5F1 is for sale for $350.
(That's a little less than the cost of the parts).
Here's the finished amp. A fuse socket replaces the old on-off switch. The lamp is a 6VDC instead of the LED. The volume knob also turns on the amp.
Take out the circuit boards. The ceramic tube sockets are soldered to the board; I will use new sockets for the rectifier, the pre-amp. and the power tube.
Here is the new circuit laid out on the eyelet board. I had to drill some holes to line up the the chassis mounting standoffs. I did end up bypassing the V1 cathode resistor with an 8 µF cap for more gain.
I used the new Jensen 6" AlNiCo 5 speaker. It sounds really, really good!
Converting a Champion 600 RI to a 5F1 Circuit
The circuit in the chassis. The pre-amp socket in under the board, so pay attention to clearances under there. I used a new 5F1 Classic-Tone Power transformer, since we are adding a rectifier, but I used the original Champion 600 Output transformer.
The RI Champion 600 has some horrible fuzzy grill cloth that does a good job of muffling the sound of the speaker. I changed it to Fender Oxblood grill cloth; it looks better and sounds better.
The whole circuit is covered in fish paper, because the leading edge of the circuit board tends to sometimes contact the foil lining inside the cabinet and make nasty noises.
There are lots of RI Champion 600s on eBay and elsewhere. I found one that didn't work for $50. I didn't care that it didn't work - I wanted the chassis and cabinet to turn it into a Champ 5F1.
The 5F1 circuit is well known as a great sounding amp, especially when cranked up. This was supposedly the amp that Clapton used in the studio to record "Layla".
By the way, the 5F1 layout, on the right, has several errors in it. Don't go by the layout if you are building this amp
There's no ground on the volume pot, for instance.