TO-3 SYMASYM

[Rudi_Ratlos]

Some time ago my friend Joe asked me, if I would like and design an AMP with 2 pairs of TO-3 output transistors.

Both, Joe and I, have a couple of MJ2119x transistors at hand, which are worth to be used.

I studied some of the DIY - AMPs in this forum and felt, that Michael Bittner's SYMASYM would be the best match to do the job.

I transferred his SYMASYM version 5.3 into EAGLE, did not change anything in the frontend, but added the pairs of TO-3 in the backend.
DADOD (thank you very much!) simulated the resulting AMP in LTSpice: the results look perfect!

I have attached the schematics as a PDF-file.

After finishing the layout, I had some space left on the bottom right and left side of the PCB and implemented a standard capacitor-multiplier
for the frontend there.

This is the resulting layout:



The red lines indicate tracks, that are running on the top side.
The TO-3s will be mounted on ALU-brackets.
The size of the PCB is 150 x 100mm.

Joe and I want the PCBs to be etched professionally, having the same quality as the PCBs, that I offered in my group-buys
for Carlos Mergulhao's DX Blame (see the picture below).



Since the SYMASYM, the backend and the capacitor-multipliers are proven circuits, we won't do prototyping.

In order to get a decent (about 13€ per PCB) price from the etching company, I must order at least 10 PCBs.

Maybe some of you like this design (SYMASYM with TO-3) and join the party.
I am sure, it will give you a big bang for your bucks.
Take a careful look at the schematics then and tell me, if I shall change anything.

Best regards - Rudi_Ratlos

[pinkmouse]

Nice project! However, the combination of rounded and angled traces does jar a little.

[Rudi_Ratlos]

I will do some final cosmetics to the layout, be sure!

Best regards - Rudi_Ratlos

[pinkmouse]

Yeah, I know. I frequently spend longer tidying up cosmetic stuff than working out the actual layout.

[metal]

Thanks to Rudi who created the asc file and sent the other models included in his asc file.

[Neutrality]

Nice layout.

[Rudi_Ratlos]

I have just finished the "cosmetic improvements" of the layout and the silkscreen of the TO-3 SYMASYM - PCB.
Here it is:



Since there is some interest in the PCB in the German Analog-Forum, I will be able to order the minimum amount of PCBs.

Rich: are you still interested?

Best regards - Rudi_Ratlos

[jmmartins]

Hi

I'm also in for a couple of PCB's

Thanks

[digits]

Rudi, I see you moved the traces there around the top left TO-3, I didn't like the first one, and the second one you got almost right. I see you now allowed space for the mounting screw, but if possible I suggest you bring the left trace back out to the side to reduce capacitance between the two traces, unless of coarse you think a little in that position is benneficial, other wise nice work. I know Carlos would drive you mad to get all those TO92 transistors in a row

[Luke352]

Do you have an idea on what postage would cost for a pair of boards to Australia? I may be interested in a pair.