Cobra 148/2000/Grant XL
TX
C46 Change to 2.2uf mylar/polyester film or non-polarized electrolytic
C101 Change to 1.5uf tantalum 16 to 50 volt
C102 Change to a 910pf ceramic disc
C104 Change to 2.2uf tantalum 16 to 50 volt
C108 Change to 1uf to 2.2 uf tantalum 16 to 50 volt
I found that if you have a very deep voice start with 1uf on C108
and work up if need be.
If you need more highs on tx Change C 105 to .001 to .0001uf mylar/polyester film The smaller you go the more highs you get.
RX
C71 Change to 1uf mylar/polyester film or non-polarized electrolytic
C75 Change to .001 to .0001uf this will give you more highs on rx
optional
C76 Change to 2.2uf mylar/polyester film or non-polarized electrolytic
C182 Change to .001 to .0001 for more highs on rx and tx
optional
C183 Change to 2.2uf mylar/polyester film or non-polarized electrolytic
C187 Change to 2.2uf mylar/polyester film or non-polarized electrolytic
With C75 and C182 you can start with no Change to them, then if you feel you want more highs then change them out
Goldfinger's cobra 29 hi fi mod
Cobra 29LTD with the TA7222AP audio chip
Receive:
Change C33 and C40 to 2.2uF non-polarized electrolytic
More highs?: remove C204 (some year ranges don't have this cap)
Transmit:
Change C69 to a .001uF disc
Change C68 to a 1uF Tantalum (some radio's already have a 1uF in them)
Change C37 to a .068uF mylar (or parallel a second .033uF mylar with the existing one)
New 2010/2011 Cobra 29LTD (TDA2003 audio chip)
Receive:
Remove C170
Change C33 and C40 to 2.2uF non-polarized electrolytics
Transmit:
Change C68 to a 1.5uF tantalum with the + side towards the right side of the radio.
Change C69 and C125 to .001uF disc
Change C37 and C43 to .1uF mylar
I did this mod on my 29lx and the receive is awesome. Crystal clear with less static sound. If you can't find non polarized electrolytics you can do what I did which is take two 4.7uf and tie the neg leads togeather and use the pos leads for through hole. Two 4.7uf caps in this fashion gives you 2.4uf give or take. The only part I didnt do was remove c170 which I can not find in the lx. But transmit has gotten great reports compared to the stock setup. I also did the irf 520 mosfet mod which gives the lx roughly 30 watts pep. Hell of a nice radio.
Cobra 25LTD Classic (TA7222AP)
Receive:
Change C32 (front center of PC board) to a 2.2uF mylar or NP electrolytic
Change C54 and C56 to 2.2uF NP electrolytic
Change C67 to a 1000uF 25 volt electrolytic
more highs? Change C151 to a .001uF disc or mylar
Transmit:
Change C90 to a 1.5uF 16-50 volt tantalum observe polarity.
Change C96 to a .001uF disc or mylar
Change C89 to a .033uF (333) green mylar
From Goldfinger:
I almost always use a mylar or polypropylene for C32. The signal levels are low there so using a high fidelity cap is a noticeable upgrade.
C54 and C56 are in a higher level area of the chain so the small/handy radial lead non-polar's are fine.
All mylar's is also fine if you can squeeze them in!
Hi Fi mod for ept3600 series board
Receive:
C36: Change to a 2.2uF, 50 Volt (or better) mylar/polyester film
C38: Remove for more highs
C39. C154, C155: change to 2.2uF 50 volt (or better) Non-polarized electrolytic or mylar/polyester film
C157: Change to a 2.2uF, 16 Volt (or better) tantalum (observe polarity)
Transmit:
C129: Change to a 10uF, 16 Volt (or better) tantalum (observe polarity)
C187, C191: Change to 2.2uF, 50 volt (or better) mylar/polyester film
Hi Fi mod for ept6900 series board
Galaxy 900 series radios 919 through 979
Receive
Remove C39
Change C78, C40 and C185 to 2.2uF non-polarized electrolytic
To add more highs change C184 to a .001uF ceramic disc
Transmit
Need more gain for running a stock mic or noise cancelling mic?
Change R-176 from a 270K stock, to a 470K.
Want more Bass?
Change C-154, a .22uF 16V tantalum, to a 3.3uF 16V tantalum.
Change C-171 and C-235 to .47uF 50-100 volt Mylar.
For even more Bass:.
Change C-154, a .22uF 16V tantalum, to a 10uF 16V tantalum.
Change C-171 and C-235 to 2.2uF, 50-100 volt Mylar.
(the 2.2uF non-polarized and the 10uF tantalum available at Radio Shack)
Hi Fi mod for Magnum S series
Receive:
C36 - change to a 1uf non-polarized electrolytic (radio shack) Need a little more bass? Use a 2.2uF non-polarized
C39 - change to a 2.2uF non-polarized electrolytic
C57 - change to a 2.2uF 16-25 volt regular electrolytic (observe polarity)
C155 - change to a 2.2uF non-polarized electrolytic
C159 - change to a 2.2uF non-polarized electrolytic
more highs:
Remove C38, or if you only want a little more highs, change to a .001uF disc or green mylar.
NOTE: C57 is actually C157
C159 is actually C154
The schematic does NOT match the Board.
Transmit:
C128 - change to a 4.7-10uF (depending on how low you wanna go) 16-25 volt tantalum. (observe polarity)
C187 - change to a 2.2uF mylar or non-polarized electrolytic
C191 - change to a 2.2uF mylar or non-polarized electrolytic