Is it okay to do this mod :
http://cbradiomagazine.com/March%202007 ... cation.htm
and swap out the stock final for the c1969 at the same time or will it mess things up?
Multiple Mods on Cobra 29
-
marveylus22
- Light User
- Posts: 109
- Joined: Saturday 19th May 2007, 11:03
- Location: Las Vegas Nevada
-
ramblingman
- Technical Helper
- Posts: 331
- Joined: Sunday 21st Jan 2007, 16:35
- Location: mississippi
hello there,,,,,just dont jumper out the anti spiking diode,,this is a no no..this is in circuit for a reason.to protect radio against stray rf feedback..in the 29 the anti-spiking diode is d-8..and for the 25,the anti spiking diode is d-10...jumping this diode out,,will only give you a watt or two more..and its not worth doing.considering it may cause later damage...ramblinman
-
tim_spur
- Frequent Keyer
- Posts: 61
- Joined: Saturday 30th Jun 2007, 15:00
- Location: elkton,ky
- Contact:
you,ll do even better if you order the erc-2030 final power kit for the 29ltd it will really make it talk its about 10 bucks i put one in a old 29 ltd of mine and its swingin about 30 watts doing real good the kit comes with everything you need and detailed instructions with nice pics i ordered mine from http://www.pacific.us.fm/pacific2005/store/index.html they also have the good echo boards for about 28 bucks
-
nomadradio
- Technical Helper
- Posts: 78
- Joined: Saturday 21st Aug 2004, 16:17
- Location: Louisville, KY USA
- Contact:
So long as you can still get them from RF Parts Inc for under seven bucks, the 2SC1969 is the most cost-effective upgrade by far.
Converting to a MOSFET-type final transistor is more involved, more error-prone, and the results less predictable.
The 1969 is a cousin of the original final, just rated for more power.
The MOSFET parts are a different type of transistor altogether. As a result the input side of the final-amplifier circuit requires that multiple parts get altered to adapt the radio for a MOSFET final.
For my money, the marginal added power is not cost-effective.
But at least you need not change more than JUST the final to use the 1969.
And don't be seduced into thinking that the tiny increase in power you get from jumpering that diode has any practical value. Yes, you might see an additional 2 or 3 Watts of peak modulated power with the diode jumpered. But the life of the final is nearly always reduced as a result. A power increase of only ten percent or less is invisible to the folks listening at the other end. The increase on the receiver's S-meter at the other end will be less than the width of the needle, let alone enough for them to tell, or enough to affect your range. Boosting what your wattmeter reads by ten percent only affects your attitude, and NOT the radio's transmitting range. At all.
The diode wouldn't be there if the designer could leave it out. If he did, the burden of in-warranty failures would cost the folks selling the radio a LOT more than they saved leaving the diode out.
73
Converting to a MOSFET-type final transistor is more involved, more error-prone, and the results less predictable.
The 1969 is a cousin of the original final, just rated for more power.
The MOSFET parts are a different type of transistor altogether. As a result the input side of the final-amplifier circuit requires that multiple parts get altered to adapt the radio for a MOSFET final.
For my money, the marginal added power is not cost-effective.
But at least you need not change more than JUST the final to use the 1969.
And don't be seduced into thinking that the tiny increase in power you get from jumpering that diode has any practical value. Yes, you might see an additional 2 or 3 Watts of peak modulated power with the diode jumpered. But the life of the final is nearly always reduced as a result. A power increase of only ten percent or less is invisible to the folks listening at the other end. The increase on the receiver's S-meter at the other end will be less than the width of the needle, let alone enough for them to tell, or enough to affect your range. Boosting what your wattmeter reads by ten percent only affects your attitude, and NOT the radio's transmitting range. At all.
The diode wouldn't be there if the designer could leave it out. If he did, the burden of in-warranty failures would cost the folks selling the radio a LOT more than they saved leaving the diode out.
73