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Old 18th December 2012, 06:19 PM   #111
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RF immune had to do with layout on the Wakabi board.
♫♪ My little cheap Circlophone© ♫♪

Building on a PCB would be a lot easier than a perfboard build.

My perfboard layout was not RF immune until I changed the input just like post 102 above. The capacitance at the input load resistor is increased by the added overload blocker zener arrangement that averages 0.78n of diode capacitance for series pair of most glass bodied zeners. Bit of low parts count goodness there. Best to check with capacitance port of digital multimeter, but I checked quite a few zeners and they were all close. Technically, the trick is to use quiet signal zeners; however, I've almost 50x gain and ordinary zeners didn't make noise (tis damped by the 10k and caught in the 330p anyway). If you just need to remove RF, an ordinary capacitor there could do it more simply.
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Last edited by danielwritesbac; 18th December 2012 at 06:46 PM.
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Old 19th December 2012, 08:38 AM   #112
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Okay, thanks. So I ll go with the terranigma-cfp board, since mr Wakibaki is dead to us.

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Old 28th December 2012, 03:25 PM   #113
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NOS 2N3772's and BD183's located but which ones are preferable?

It will be an "old school" build, sine the donor chassis is a 60W professional amp with TO3's at the outputs. PSU will be reused, possibly with a recap.
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Old 28th December 2012, 08:23 PM   #114
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Quote:
Originally Posted by costis_n View Post
NOS 2N3772's and BD183's located but which ones are preferable?

It will be an "old school" build, sine the donor chassis is a 60W professional amp with TO3's at the outputs. PSU will be reused, possibly with a recap.
That's the same spirit of mine regarding to the Circlophone. The unique topology makes it is feasible to use what you have until respecting the specs. It is very interesting approach of that possibility of using old fashion TO-3 devices, quality transistors from golden era in a new design. I think that each build is coming to having its own characteristics somehow.

I struggled with some scholarship for a duration. I plan alternate the PCB if I could find an opportunity. CFP pcb is a product of a reputable process and cooperation in my opinion.
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Old 30th December 2012, 08:14 AM   #115
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PCB's in progress. I don't think I ll need the R-L at the output, since I ll be using such slow power transistors. And yes. I actually fond them in the local shops.

Click the image to open in full size.
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Old 30th December 2012, 08:47 AM   #116
Elvee is offline Elvee  Belgium
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Quote:
Originally Posted by costis_n View Post
PCB's in progress. I don't think I ll need the R-L at the output, since I ll be using such slow power transistors. And yes. I actually fond them in the local shops.

Click the image to open in full size.
The 2N3772 are really too slow, they will work but HF performance will be abysmal.
The BD183 are not exactly fast, but they are 4 times faster, that is an improvement.

Also, I don't recommend using the CFP version, it is less clean than the official version.
You can wire your CFP PCB as a normal one (or you can try both and compare).
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Old 30th December 2012, 08:52 AM   #117
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Aha, thanks!

I like the constant impedance of the CFP version, but can use non-cfp as well, since I have a tube buffer. Perfect application for that.
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Old 1st January 2013, 09:01 PM   #118
Piersma is offline Piersma  Netherlands
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Default CFP update

The silkcreen of CFP Circlophone states in post #96 by mistake that the phase inverter is the PNP 2SA1209. This should be the NPN 2SC2911.
For your information, the attached PCB lay-out in post #96 is correct and tested.
Attached Files
File Type: pdf silkscreen_CFP Circlophone .pdf (42.7 KB, 86 views)
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Old 1st January 2013, 09:06 PM   #119
Piersma is offline Piersma  Netherlands
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Default Measurement results CFP Circlophone

Last week i have done some real life measurements on the CFP Cirlophone.
Attached files show the specs.

have fun building.

regards,
Piersma
Attached Images
File Type: jpg Circlophone PIC.jpg (296.0 KB, 231 views)
File Type: png THD&N Circlophone CFP.PNG (33.7 KB, 225 views)
Attached Files
File Type: pdf CFP Circlophone_PCB version.pdf (47.5 KB, 253 views)
File Type: pdf CFP Circlophone assembly.pdf (54.2 KB, 98 views)
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Old 2nd January 2013, 07:54 AM   #120
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OK thanks for the update.

And guess what, I opened up the "donor" box and there are 4x 2SD424 original Toshibas. Seems like the best option so far, am I correct?
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