Cheap talkie amplifier

[KA5PIU]

Hello.

Now that this is a proven design,,.
As you must be aware of by now, 800Mhz analog radios are now dirt cheap.
So, who wants 800Mhz radios?
I pulled apart a 25 watt mobile and discovered that the output section is but one chip.
T/R switching and filtering are all done on the same board that the output module is mounted on, PN diodes.
After pulling the main board I used that and depopulated everything I did not need, leaving the audio section, power and of course, RF output.
I now have a broadband 20+ watt talkie amplifier.
Leaving the audio section allows for 2 watts of audio and the mobile microphone circuit.
Where the channel display was is now something useful, an incandescent light. :-D
The holes for volume and mode are now RF and audio/DC to/from talkie.
This radio suffers from that black chit from the leaking caps thing.
My first though was to try and salvage it, but why? the display board is toast for sure.
So, plop in a bunch of new caps after cleaning the board and it works.
This was out of something awful, perhaps a garbage truck?
Anyhow, YOU can do this.
It took very little to get this to produce clean RF, simply limit the RF drive so that it does under 25 watts and everything is fine.
100 milliwatts is perfect.

[NQ6U]

Hello.

Imagine if you will a reincarnated thread.
A concept brought back from the dead to haunt living Islanders with craziness from the Other Side.
The Rudy Zone.

[KA5PIU]

Hello.

Actually, something that I had a chance to complete.
Once I understood what I needed to do and how to do I was able to complete this.
The metal frame of the chassis and heat sink are already there as well as the PC board and housing.
The radios themselves are super cheap to free.
This is but one example.
http://cgi.ebay.com/Motorola-MHW820-1-800MHZ-20w-PA-MODULE-51-80110E01-/380309589905?pt=LH_DefaultDomain_0&hash=item588c37cf91
So you can go from just the module to the entire radio.
Again, there is Nothing that limits lower frequency operation, there is no sort of filtering in the module itself.
Simply take out Everything you do not need or bolt the module inside another amplifier, your option.

[kb2vxa]

"...there is no sort of filtering in the module itself."

OK, and what is there to prevent this abortion from spitting out harmonics and spurs from DC to light?

"A concept brought back from the dead to haunt living Islanders with craziness from the Other Side.
The Rudy Zone. "

Yeah, deja vu all over again.

[KG4CGC]

WART

[kb2crk]

just more of the exact same old bullshit...

[NQ6U]

WART

[KA5PIU]

"...there is no sort of filtering in the module itself."

OK, and what is there to prevent this abortion from spitting out harmonics and spurs from DC to light?

"A concept brought back from the dead to haunt living Islanders with craziness from the Other Side.
The Rudy Zone. "

Yeah, deja vu all over again.

Hello.

That is what I discovered at first. ;) See the CB radio entry.
The VX-7R set for its lowest power setting works wonders.
Even at its highest power setting it is within limits.
But, at 2 watts it is perfect, it puts no more power out after that.
I am thinking of putting together an amplifier and power supply that is the size of a full sized talkie like the MX or the like.
Strip out everything but the speaker and microphone and and mount a 15 watt RF amplifier in it as well as an audio amp.
The original battery packs were NiCad, the biggest packs with modern chemistry cells can provide the level of power needed.
And, again, the FT-817 uses the very same concept, one output section for 1.8 to 450MHz.
The trick is to start with a clean signal, add band filtering just like one would do with an HF amplifier, and go for it.
In effect, a super wide band version of this.
http://www.mirageamp.com/Product.php?productid=BD-35
At 15 watts vs 5 watts for what the talkie can do on its own that is quite a bit of gain.
But, most modern talkies get hot on high power quickly.
Set one at 300 milliwatts, set this thing on low, and you have 5 watts, and you can power your talkie, and you have 5 watts of audio.
And, it is possible to add P-25 but like the Amateur radio itself, this is NOT FCC approved.
So, I am not doing anything new, stuff like this is already for sale.
I am doing this in the cheap.

[W5GA]

WART

[WØTKX]

http://www.aqpl43.dsl.pipex.com/MUSEUM/COMMS/ear/bolling%20field%201921%20a.jpg

[KA5PIU]

http://www.aqpl43.dsl.pipex.com/MUSEUM/COMMS/ear/bolling%20field%201921%20a.jpg

Hello.

Pre-RADAR aircraft detection.
The funny part is that it worked.
http://www.stonevintageradio.com/items.php?CA=8
Early speakers were little more than earphone elements and excellent acoustic coupling by way of a horn.
Take the modern MP3 player, connect it to a pair of old horn speakers and you will have room filling sound.

[NQ6U]

I once read that during WW I, the French put trained parrots at the top of the Eiffel Tower to detect incoming aircraft.