PDA

View Full Version : New "CB" amplifier.



KA5PIU
02-07-2011, 08:18 PM
Hello.

Want an amp that is as "Nasty" as they come?
As you are aware, analog 800MHz equipment is plentiful and cheap right now.
A lot of radios use an output module that is the complete final amplifier.
On all of the ones I have been able to find so far there is no filtering whatsoever, it depends on the signal to be clean and in the designed band.
So, what happens when we input an AM signal at 28MHz in?
Since this is class C, we get distortion, lots of it.
But, unlike the CB amps of old, where the transistors were only good to 30MHz, we get to go all the way up to 800MHz!
So, 28, 56, 84, 112, 140, 168, 196, 224, 252, 280, 308, 336, 364, 392, 420, 448, 476, 504.
My guess is that it keeps on but the older spectrum analyzer only goes to 512Mhz.
This was a sawtooth wave into a dummy load.

NQ6U
02-07-2011, 09:33 PM
http://www.youtube.com/watch?v=e5JCp2Hd5L8

NA4BH
02-07-2011, 09:51 PM
Nothing like promoting illegal activity.

NQ6U
02-08-2011, 01:14 AM
Nothing like promoting illegal impossible activity.

Fixed that for you.

n2ize
02-09-2011, 10:38 AM
Howw bout a 6 pill Dave Made + a DOSY Meter... :hyper::(:)

N2CHX
02-09-2011, 10:40 AM
http://www.youtube.com/watch?v=NWdrO4BoCu8

KB9YCO
02-09-2011, 11:23 AM
At the risk of stereotyping CB I just have to say, "Four ten, roger, right on, no doubt about it... and I just got down!"

KA5PIU
02-11-2011, 07:35 PM
Fixed that for you.

Hello.

Try it sometime.
Mini circuits has a warning about this very thing.
The trouble is that amplifier was never intended to operate without a signal in the frequency range in question.
Look at HF amplifiers, the band filtering solves the problem, if properly tuned.
Take an HF amp and disable the band filtering for a moment and bias it to class C.
Now inject a frequency, prefer AM and over driven,at least 2 octaves below the upper limit.
In effect you have a sawtooth wave.
See what you get.
In effect you are running a CB amplifier.
You can also be lazy and just use a CB amplifier.
Real nasty output.
Now, connect a CB radio, or simulation, to an amplifier that can operate to UHF that has no filtering.
Nasty signal, but it is all over the place.
Again, very easy to disprove. ;)
Remember that the commercial amps are intended for FM service, not AM, so they are class C.
Taking them outside, way outside, the intended passband does not help. ;)
I am actually thinking of mounting an 800Mhz 60 watt final module inside a Texas Star amplifier on the side, adding BNC connectors, and calling it a "Dual use" amp. ;)
I would never operate this thing on the air, but I can sure have fun anyway.
Perhaps I can present this to the ARRL as a project? ;)

N2CHX
02-11-2011, 07:38 PM
NOM NOM NOM

KA5PIU
02-11-2011, 08:04 PM
NOM NOM NOM

Hello.

Want a VoIP chat?

NA4BH
02-11-2011, 08:07 PM
Hello.

Want a VoIP chat?

Echolink?

KA5PIU
02-12-2011, 03:11 AM
Hello.

What node?

NQ6U
02-13-2011, 10:27 PM
WART

NA4BH
02-13-2011, 10:28 PM
Hello.

What node?

Axillary Lymph

WART

W7XF
02-16-2011, 08:17 PM
No excuses on Da Bowl!

WART

KA5PIU
02-17-2011, 06:34 PM
Hello.

27.185MHz. ;)
What number of you Really understand how a CB radio generates an RF signal.
By this I mean from the channel selector to the PLL a chip and the reference oscillator.

w2amr
02-26-2011, 04:31 AM
Hello.

27.185MHz. ;)
What number of you Really understand how a CB radio generates an RF signal.
By this I mean from the channel selector to the PLL a chip and the reference oscillator.:wtf:

kb2vxa
02-27-2011, 10:56 AM
Hello.

CB starts out with cats, a blender and a microphone. Then it multiplies the frequency until it comes out on 27.185MHz. That's why whenever you listen to channel 19 it sounds like cats in a blender.