Cobra 29 mod problem ?

StrightClaw · Post by **StrightClaw** » Tuesday 24th Apr 2007, 22:57

I have a Cobra 29 that I did the 2030 mod to. It will dead key 2 watts, swing is 30-35 watts. The radio talks fine. I added my palomar 5500 to it and it still talks fine. I installed an Astatic Echo Board ,and with it Im told I have a Hum on transmitt. I have removed the Palomar and it works good with the Echo Board. I have a HD Night Hawk I tried, but get the same result as the Palomar.I like the Echo board because of the clear audio I get with it. I dont use the Echo effect. Anyhow my question is could it be that the 2030 mod is makeing to much Audio along with the Echo Board, and thats whats causing the Hum. I guess the only way to find out is put the stock Final back in it. Any other Ideas ?

kc8mob · Post by **kc8mob** » Wednesday 25th Apr 2007, 1:24

Well you said it only happens when you're using your linear.

Seams like you have a ground or sheilding problem with the audio in regard to the echo board. That hum you're getting is a result of all that high quality RF that CB linear is making. Most likely.

So make sure all of your audio lines are sheilded, or grounded properly.

StrightClaw · Post by **StrightClaw** » Wednesday 25th Apr 2007, 10:59

Thanks for the reply kc I don't know what else I can do to shield the RF i have wrapped the board with copper tape grounded everything possible and the wireing is already shielded. Im out of town but when i get home ill try changing back to stock. i still think to much audio. I guess im hard headed.

Turkish · Post by **Turkish** » Wednesday 25th Apr 2007, 14:42

Can you describe that 2030 mod you did. or post a link to where I can find directions to it. I also have a cobra 29 and I am playing with the Super Swing mod with it currently. I am also curious about where you got your linear I am looking for one. If you have any helpful information let me know and i will give you my email address to pass it on.

kc8mob · Post by **kc8mob** » Wednesday 25th Apr 2007, 14:53

Here is a reputable source for linears: http://www.amateurlinearamplifiers.com/cgi-bin/cart.cgi

and just get a 2SC1969 final for your 29. they're still availible so use it. Much easeir. The 2030 is a replacement for the 1969 since it's been discontinued. But you can still get them

The 2030 requires allot of part replacements and modifications.

If you give me your email add. I'll send you all the info you want on the 2030. PDF. it has directions and everything. I've done about 20 of them

The 1969 gives the saem power result, but it's a direct drop in replacement.

StrightClaw · Post by **StrightClaw** » Wednesday 25th Apr 2007, 23:07

As for a amp. The source kc posted is a good one. Or if you ever use eBay you can look around there.Some people don't like useing this as a source but Ive had good result there over the years.
I differ with kc a little her on the 2030 mod, with some of the older cobra 29s you'll get good result just changing the final, but some require more. Iv'e had different results. If you use the 2030 and dont get the result your looking for I found by replacing the additional parts listed for the 1969 mod will bring it up. You can find what you need to know here for the 2030 http://www.cbtricks.com and the info for the 1969 mod here
http://www.dtbradio.com/tips.html hope this helps good luck.

StrightClaw · Post by **StrightClaw** » Wednesday 25th Apr 2007, 23:35

Sorry turkish I forgot to say you may have to replace you driver. You can use this site for the mod and it list the steps. http://www.714xpress.net/714mods1.html

kc8mob · Post by **kc8mob** » Thursday 26th Apr 2007, 1:17

Well you can pull some ceramic caps and switch some around when you do the 1969. But it's a drop in mod. Unless you're getting 40 watts PEP easily out of your rig with the ERF 2030 it's allot of work.

But, there is no more right way with either so it's up to the guy who's willing to experiment with his radio.

Turkish · Post by **Turkish** » Thursday 26th Apr 2007, 11:56

I greatly appreciate all the help here guys I just ordered a 1969 final and 1957 driver for my radio. I really cant wait to install them and see what I can get out of this thing.

kc8mob · Post by **kc8mob** » Thursday 26th Apr 2007, 13:25

Uhhh. Your radio already has a 2sc1957 driver in it.

Turkish · Post by **Turkish** » Thursday 26th Apr 2007, 14:41

Nope C2314 and C2028

kc8mob · Post by **kc8mob** » Friday 27th Apr 2007, 3:39

Wow they changed it then.

kc8mob · Post by **kc8mob** » Friday 27th Apr 2007, 3:41

Or maybe it's the 2sc1057 that's stock in those radios. I know it didn't use to be what you said.

Anyways, if you're going with the 2sc1969. You don't need to replace the driver.

StrightClaw · Post by **StrightClaw** » Tuesday 1st May 2007, 22:30

OK this may help others so Ill post my fix for my radio. I was able to get it to talk without the hum by takeing the ground off the radio ? And turning the audio down inside the radio. I had it wide open and it worked fine untill I hooked it to my box. Anyhow Audio halfway down inside and on the radio itself turned it down a goodways. I still have good clean clear audio with the echo board so I guess Ill just go with it. Would you belive it disconnect the ground ?????

kc8mob · Post by **kc8mob** » Wednesday 2nd May 2007, 8:23

You have ground loop problems. You're getting your power ground through your coax. Means you antenna is grounded well, which is good.

StrightClaw · Post by **StrightClaw** » Wednesday 2nd May 2007, 10:33

With all due respect my power connection and my ground both go to the battery.

StrightClaw · Post by **StrightClaw** » Wednesday 2nd May 2007, 10:45

Sorry I should have explained myself better. The ground that I removed was one that I had connected to the case of the radio not the power ground. I also have a ground attached to the case of my amp. But unlike the radio I get a hum if I remove it.