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View Full Version : Texas Star Amplifiers in legit use.



KA5PIU
02-13-2011, 03:39 PM
Hello.

I was surprised to learn that 99% of all hams as well as CB shop operators have no concept of how to correctly configure a Texas Star CW unit/Amplifier for a clean AM signal.
http://www.texasstar.com/350HDVschematic.gif
First off, notice that this is indeed configured as a CW Transmitter.
Notice also that this has a key/audio input.
We go from J1 to R6 to Q3 to C17 to Q4 to C11 to T1.
We also go from J1 to R6 to Q3 to X1 and R9.
SW 4 selects where the audio signal goes.
As you can see, this thing can do CW, AM and FM.
In the AM mode it is true high level modulation, T1 acting as the modulation transformer.
In FM mode it deviates the crystal X1.
There are 2 more boards that must go in to make it a 350 watt PEP AM transmitter.
A modulation amplifier and driver amp.
This does around 60 watts carrier so the modulation amp is around 30 watts.
In FM mode nothing extra is needed.
This is NOT an SSB amplifier! it is class C !!!!!!!!!!!!!!!!
You can do the external exciter mod and do FM or CW with no problems whatsoever.
But for AM it is very important that it be modulated directly for a clean signal.
To say it has no filtering is not correct, the output transformer limits the frequency of operation to a maximum of of about 30MHz as well as the fact that gain drops off very quickly.
Since this is a 10 meter monoband transmitter/amplifier nothing else is needed.
Operation on 26.62MHz in the FM mode works well within specifications required.
On AM with the 2 extra boards it meets all NTIA requirements.
Again, this is a monoband unit, operation outside of 22MHz to 30MHz is not an option.

KG4CGC
02-13-2011, 03:47 PM
bullshit

I said it first

WART
(worked all Rudy threads)

WØTKX
02-13-2011, 04:15 PM
http://www.cbtricks.com/Amp/txstar/mod_grande/tour/graphics/dsc00001_sm.jpg

PA5COR
02-13-2011, 05:03 PM
Yuck.
I prefer my Heathkit SB-1000.
Clean output and all.

VE7DCW
02-13-2011, 09:59 PM
bullshit

I said it first

WART
(worked all Rudy threads)

I love it!!! ...... WART a new twist in the measurement of WTF's in all of Rudy's threads!! Bravo!! :agree:

NQ6U
02-13-2011, 10:24 PM
WART

KC2UGV
02-16-2011, 12:20 PM
Well, I'm sure it can be done. I mean, after dumping $10K into a rice-burner, it gets in the neighborhood of a stock Mustang with a 5.0...

N2CHX
02-16-2011, 01:45 PM
Want clean output from that thing? This should do it:



100 mH
AMP >---------------UUUUUU----------------------- > ANT
| |
> __
< 50 ohm __ .1 uF
> |
< |
| |
___ ___
- -

:stickpoke:

PA5COR
02-16-2011, 01:54 PM
I prefer a sledge hammer to that...http://theden.satpimps.com/images/smilies/jaw.gif

N2CHX
02-16-2011, 01:56 PM
I prefer a sledge hammer to that...http://theden.satpimps.com/images/smilies/jaw.gif

Well... Admittedly you'd probably get more output :lol:

N8YX
02-17-2011, 10:12 AM
I like my IC-2KL setups.

With the ALC/PO limiting adjusted correctly they're pretty much goof-proof.

WØTKX
02-17-2011, 10:59 AM
This, maybe two in line for shenanigans.

http://img.auctiva.com/imgdata/1/1/9/5/6/1/1/webimg/432450342_o.jpg

N2CHX
02-17-2011, 11:16 AM
This, maybe two in line for shenanigans.

http://img.auctiva.com/imgdata/1/1/9/5/6/1/1/webimg/432450342_o.jpg

Nice, but it won't turn a square wave into a sine wave.

KG4CGC
02-17-2011, 12:18 PM
It's from Radio Mart so it's already broken.

N2CHX
02-17-2011, 12:20 PM
It's from Radio Mart so it's already broken.

Probably has a grid leak. :rofl:

KG4CGC
02-17-2011, 12:25 PM
Probably has a grid leak. :rofl:
Waffles?

N2CHX
02-17-2011, 12:30 PM
Waffles?

French toast.

KG4CGC
02-17-2011, 12:32 PM
French toast.
Third Base!

N2CHX
02-17-2011, 12:36 PM
Third Base!

Home run!

KA5PIU
02-17-2011, 06:31 PM
Hello.

All fine and well, except any sort of filtering action in that thing is going to be GONE! see next ebay listing for components for sale from said filter. ;)
Remember that I started this in a sarcastic tone, but have provided the needed links so you can build one.
http://cgi.ebay.com/Motorola-MHW820-1-800MHZ-20w-PA-MODULE-51-80110E01-/380309589905?pt=LH_DefaultDomain_0&hash=item588c37cf91
That thing will work just fine with 100 milliwatts of drive, so 300 flat topping AM should be just about right. ;)
I am pointing this out as I am sure that at some point somebody is going to try it. ;)
But, the 900MHz version works wonders with Nextel Direct Talk! we were able to squeeze 20 miles out of it!
There are only 2 Nextel mobiles offered in the US and both do 100 milliwatts at 900MHz.
On the heatsink is a place for another connector, it just needs to be drilled out!
Adding the module means grinding a bit of metal and the drill and tap boogie.
Simply cut the trace on the board where it is to feed the antenna and a bit of RG174 from there to the small bit of board that the module is on and on the the new connector and you have it made.
Anything over 5 watts is overkill, even the 2 watt modules intended for 900MHz cellular will work well, and that is plentiful.
So, who uses this type of thing, 200 watt "CB" amplifiers and 2+ watt 900MHz Nextel Direct Talk?
Truck drivers who want a direct line of communications with someone else and does not want to do cellular or regular CB.
The police assume that "The shipment" will run straight through, wrong!