858 sideband chassis hifi

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Goldfinger
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858 sideband chassis hifi

Post by Goldfinger »

This chassis has a mod transformer so it's can't handle bass below 80hz. (like the 29LTD)
This is a mild bass mod.


TX:

Change C69 to a 10 uF 16 volt electrolytic (if it isn't already). Observe polarity.
Change C61 to a .22uF mylar
Change C77 and C78 to 1uF-2.2uF 16Velectrolytic or tantalum. Observe polarity.
Change C83 and C82 to .22uF mylar or metal film
Change C84 to a 2.2uF or 3.3uF 50 volt electrolytic

need more treble?

Change C73 and C75 to .01 uF ceramic disc
Change C200 and C201 to .001 uF ceramic disc



RX:

Change C40 to a 1uF or 2.2uF mylar or non-polarized electrolytic
more highs? lower the value of C51
Change C80 to a 1uF or 2.2uF mylar or non-polarized electrolytic
Change C95 to a 100uF 25V electrolytic, observe polarity

Direct inject: Inject through a 3.3uF cap to the junction of C60 and L10
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Robb
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Re: 858 sideband chassis hifi

Post by Robb »

Waaaay cool - and thank you!
a365
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Re: 858 sideband chassis hifi

Post by a365 »

Hello GF:

I wonder if the value for C95 is not a typo

Original value in the schematics for Cobra 138xlr and Realistic TRC-449 shows 470uF/16V


Thank you for your reply
A365
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Goldfinger
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Re: 858 sideband chassis hifi

Post by Goldfinger »

Yes, looks like a typo...
Thanks for pointing it out. I'll revise C95 to 1000uF.

Edit: until I update the forum software, I can't edit the older post, This post will have to reflect the revision.
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a365
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Re: 858 sideband chassis hifi

Post by a365 »

Thank you GF for your reply :mrgreen:


Regards
A365
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