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2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Sun Nov 11, 2012 1:46 pm
by Goldfinger
Receive:

Change C45 and C48 to 2.2uF mylar or non-polarized electrolytic
Remove C47
Change C224 to a 2.2uF, 25 volt electrolytic or Tantalum. Observe polarity
Change C221 and C222 to 2.2uF mylar or non-polarized electrolytic


Transmit:

Change C155 and C141 to 10uF, 16 volt Tantalum. Observe polarity
Change C240, C298 and C299 to 2.2uf mylar or non-polarized electrolytic

Sideband/FM Transmit:
Change C131 and C136 to 2.2uF mylar or non-polarized electrolytic


Note: For the transmit to have full width, the audio in/out wires on the echo board (one wire from J2 and one from J3) have to be disconnected and jumped together, bypassing the echo board.

Posted: Sun Nov 11, 2012 6:00 pm
by HomerBB
Goldfinger, I am not a radio tech. They seem to hate me when I take the covers off.
So could you explain exactly what is to be expected in changes from each of the modifications.

Thanks,
Homer

Posted: Mon Nov 12, 2012 2:04 pm
by Goldfinger
Most of the cap changes are extending the frequency response of the low end from 300-400 hz stock, down to 20-30 hz after the modification. Removing C47 adds more highs above 3500 hz on receive.

Posted: Mon Nov 12, 2012 5:20 pm
by HomerBB
So it is a tone change, or does it also permit better reception?

Posted: Mon Nov 12, 2012 6:19 pm
by Goldfinger
Yeah, tone/frequency response change. No changes to the selectivity or sensitivity of the receiver chain.

Posted: Mon Nov 12, 2012 6:52 pm
by HomerBB
Thanks, a lot.

It sounds like a good place to start for getting a smooth audio setup.

Posted: Tue Nov 13, 2012 11:20 am
by Goldfinger
It does make for better reception IMHO though as the receive seems cleaner and less "crackly". Plus I use middle of the road amplified computer speakers with a sub as my speaker. It really enhances the wider audio.

Posted: Tue Nov 13, 2012 12:03 pm
by HomerBB
I might have to give it a try

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Feb 29, 2016 1:41 pm
by redlght
What effect would swapping out the stock 455ht filter to a 455f that is 6Khz?

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Feb 29, 2016 3:16 pm
by Goldfinger
You will just have crisper highs from the added high end response. On 29's, I also noticed the lower bass seems cleaner when you compare a wide radio with the stock filter to one with a 6kc. (when listening to a wide transmitter)

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Sat Oct 26, 2019 9:01 pm
by Mr.Lightning
Goldfinger, I am sure this has been asked before. Can you use NON-polarized 2.2uf in place of the polarized 2.2uf? Thanks!

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Sun Oct 27, 2019 2:44 pm
by Goldfinger
I've never done it on a CB but I'm sure you can. Just make sure they are 25 volt or higher.

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Nov 09, 2020 9:21 pm
by DoubleR0788
What's the injection stops for this board thank you, for am and ssb

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Tue Nov 10, 2020 8:39 am
by Goldfinger
C299 for AM, C131 for SSB

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Sep 13, 2021 9:53 pm
by DoubleR0788
Is the injection cap a 2.2uf or 10 if and witch side the cap do ya inject threw .

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Tue Sep 14, 2021 8:19 am
by Goldfinger
Use a 10uF into the R281/R282 end of C299.

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Wed Sep 15, 2021 9:10 am
by DoubleR0788
I used a 2.2 uf but there some feed back over the recive . I wonder if a 10 uf would stop that .

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Wed Sep 15, 2021 12:06 pm
by Goldfinger
It's virtually impossible for the direct injection on a Galaxy/Ranger to feed back into the receive unless you aren't injecting in the right place. Are you sure the radio you are working on has the ept295013z board?

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Wed Sep 15, 2021 1:44 pm
by DoubleR0788
Galaxy saturn turbo that has the 2950 orange face board .

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Wed Sep 15, 2021 1:46 pm
by DoubleR0788
C299 farthest away from the case with a 2.2uf 50v cap

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Thu Sep 16, 2021 9:24 pm
by Goldfinger
Pull out C298 and see if it stops.

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Sep 20, 2021 6:44 pm
by DoubleR0788
You said c298

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Fri Sep 24, 2021 8:18 am
by Goldfinger
Yes, i wanted to see if the audio was back-feeding either through the mic amp or the talkback circuit.

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Mon Oct 04, 2021 12:18 pm
by DoubleR0788
Removed the cap like suggested and no more feedback over speakers .

Re: 2950, 2970, 2527, DX22b etc. (ept295013z) mods

Posted: Tue Oct 05, 2021 8:46 am
by Goldfinger
It looks like something is funny with the talkback circuit or something. With that cap removed you won't be able to use the mic jack for modulation but if you are direct injecting, it won't matter.