Direct inject cobra 2k

[1502gulfcoastMS]

Im going to direct inject my 2k via c174. I watched a video on YouTube. I have a couple of questions about it. I i. I will post a link to video.
1. It says to use a dptd switch. I think that should be a dptd switch?

2. I'm going to use a 1/4 jack, this video only shows hooking up one wire to a bnc connector. With this be the same for a 1/4 jack? If not what are the connections?

Video link

 

[543_Dallas]

DPDT is what you need to switch from the rack gear to the stock mic. The 1/4 in jack will work the same as the bnc. If you go with the 1/4" jack find one isolated from the chassis or run a premade cable out the back of the radio. An XLR would be better. Shield to the case, negative to the circuit board ground and positive to the positive side of c174 through a DC blocking cap.

Once you get that done a 3 diode ultra modulation circuit can be used in these rigs with good results if used conservatively.

 

[357]

I would move those connections as far away from the PS as possible.
I would use the 1/4" or a xlr plug.
I'd recommend coax shielded connections too.
I'd cut the trace under the board and work from there also.

That board rocks on AM.
If you haven't volted the final yet, thats essential.
R131 leave the limiter transistor alone.

These are monsters then

 

[543_Dallas]

Volting the final makes for big positive peaks and a squared off negative peak that never reaches baseline. If you're a watt meter watcher it's great but it's a hack mod.

The modulation limiter will not function when you do the direct inject thing. You need some kind of peak limiter in your rack and it should be the last piece of equipment in line.

 

[dave457]

Volting final and hifi don't go together

 

[wavrider]

Direct inject, audio rack mount??

Sounds like a lot of time a money invested to sound like a well aligned cobra2000 with a turner +3 wired to it

 

[543_Dallas]

Direct inject, audio rack mount??

Sounds like a lot of time a money invested to sound like a well aligned cobra2000 with a turner +3 wired to it

Yes, turner +3 plugged into the front of a cobra 2000 does the exact same thing. Anything useful to add or just trolling?

 

[wavrider]

Trolling??if that is what it is I have been doing for about 7 years
on these boards.

The hi-fi craze hit amateur bands years ago, then again most of the amateur transceivers have detector that will cover broad frequency ranges so the hi fi can be appreciated.

The wide band width and frequency range is nice, but not worth a hoot if the biggest majority of the receivers in use can not reproduce the bandwidth or frequency response in the receive section.

Not knocking it, I am all for experimenting, trying new types of audio devices, all for the fun of the hobby.

Not trolling, just wondering just how much difference the audio racks and direct injection actually make, like to see side by side comparisons on a spectrum analyzer of a well tuned cobra 2k vs a heavily modified direct injected cobra 2k.

The circuit of ANY electronic device is limited by the components in the circuit. If the transmitter is modified to transmit above and below the designed frequency then makes common sense that the receiver would have to be also.

http://www.worldwidedx.com/threads/...-setup-than-shottky-diode-receive-mod.197585/

This thread caught my attention concerning receive of direct injection hi fi audio.

 

[543_Dallas]

I agree that you can't fully appreciate it on a stock cb receiver but you hear some of it. The filters in the receiver roll off the highs and lows, that doesn't mean they cut everything off below 300hz and 3000hz (or whatever the specs are)...I feel like we've been down this road before. Many of us do modify the receiver to open it up. A few use an SDR or a separate receiver all together. If people couldn't tell the difference between this and a stock 2000 with a turner mic and I hadn't heard the difference myself I wouldn't waste my time with it on 11 meters.

 

[DJboutit]

Just get this and you will not have to mod your radio

http://onairdesigns.us/

 

[dave457]

Thats just an interface option, direct injection is the way to go and cheaper

 

[loosecannon]

Just get this and you will not have to mod your radio

http://onairdesigns.us/

i don't get it.
you still have to plug this into your mic input on the radio right?

if that's true, then you are still limited by the audio bandwidth of the radio itself, which, if you don't modify it, will be sharply attenuated below 300hz and above 2500hz.

no matter what frequency range you try to cram through the mic input, the radio still tailors it for communications audio unless you change that inside the radio.

what am i missing here?
LC

 

[dave457]

i don't get it.
you still have to plug this into your mic input on the radio right?

if that's true, then you are still limited by the audio bandwidth of the radio itself, which, if you don't modify it, will be sharply attenuated below 300hz and above 2500hz.

no matter what frequency range you try to cram through the mic input, the radio still tailors it for communications audio unless you change that inside the radio.

what am i missing here?
LC

Right on the money LC, radio still needs to modded

 

[357]

He's injecting it into the AM regulator, I cant see much audio bandwidth components in the way.
Thing is on SSB this wont work. Kinda wasteful of the 2000 to run it on AM when you could use a 29 like the big boys do.

 

[M0GVZ]

The hi-fi craze hit amateur bands years ago, then again most of the amateur transceivers have detector that will cover broad frequency ranges so the hi fi can be appreciated.

No it didn't and no they don't. Only one of my four amateur rigs will hear more than 3kHz. None of them will hear 6kHz on SSB. ESSB is a niche and one which is NOT appreciated by amateurs as it takes up at least twice as much space as is needed (usually a hell of a lot more if they're using a linear) and the majority of band plans don't cater for it. And its wasted on 99.9% of receiving stations who are all listening to the audio at 2.7-3kHz the same as CBers would be this.

"To those ESSB guys I say this: If you want to be a broadcast station then apply for a broadcast station license." - Riley Hollingsworth K4ZDH, lead enforcement officer for amateur radio at the FCC in his talk at Dayton Hamvention in 2007.