Messages

1

North American Shortwave Pirate / Re: XLR8 6955 USB 0001 UTC 12 Oct 2015

« on: October 12, 2015, 0048 UTC »

yep, receiving them down here, Gulf of Mexico coast.

drinking some Reasonably Corrupt Black Lager
from Shreveport Louisiana (or is that in Texas, as they say around here!)

00:38 The Clash - "Police and Thieves"

00:41  ID    "XLR8"

hard to believe I just heard "John Wayne was a NAZI"
by  MDC - Millions of Dead Cops
Music from my days ! ! ! ! !     That "album" kicks but ! ! !

2

North American Shortwave Pirate / Re: TCS 6876 AM @ 01:27 5/26/14

« on: May 26, 2014, 0141 UTC »

been hearing something on 6876 kHz for a while. . weak signal in the static.
down here near New Orleans /  Baton Rouge  

oh, it picked up... at  01:38 zulu  got The Psychedelic Furs  "Love My Way"

came back in radio room.. hearing "Whip It"  DEVO   at  0213 zulu

3

Equipment / 5 w IRF510 tx kit from QRP club.

« on: February 24, 2014, 2154 UTC »

.

I was reading about this 5 wattt  IRF510 transmitter kit the other day
in an AM Amateur Radio website.    32 dollars.   
Just add your modulator, and crystal.

http://www.4sqrp.com/NS40.php

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4

Equipment / Re: NRD-505

« on: January 30, 2014, 1636 UTC »

Yes, this is a typical problem with older AC mains powered electronics,
such as guitar amplifiers.

they have a 2 wire AC power cord, with capacitors going from the "hot" side of
the AC line to ground.....so when you touch your piece of equipment,
and then ground, you get a little shock.

I found the schematic to the 505 and is shows just this....
so remove capacitors C1 and C2, and wire up a 3-wire power cord, that has a ground.

or to make things quick, hook a ground wire from the radio to the ground screw on
your 110 VAC outlet.

5

European Pirates and Private Stations / Re: Borderhunter: 15500, 9/21, 2104+

« on: September 21, 2013, 2213 UTC »

I hear Rush  "Spirit of the Radio"   and an ID before that...
down here in the New Orleans - Baton Rouge ("Red Stick") metro area.

6

The RF Workbench / another Guerrilla transmitter is born.

« on: September 13, 2013, 0346 UTC »

I got e-mails about low power out from this circuit.
Only about a  watt or so...

http://www.angelfire.com/de/RadioAnarchy/

I went to Radio Shack and got the capacitors there...
and at work today figured out a circuit board plan to cut
out with the Dremel tool on some double sided copper board
.. .did not take long...

at first power up, I got about 5 watts of power... then I added another turn to L3 and
go a little more power.... about 7 watts.....   no problems..
for C5 I have two .001 MFD caps in series, for 500 pico-Farad.

so for L3 we should start with 6 to 7 turns,, then unwind..
also the value of these caps at C6 are not that accurate..

if you have a variable capacitor  around 1200 pico-F  for C6, that would be good.

but we are trying to keep it simple and easy, and low cost.. . .

so I built 2 just like this and have no problem getting several watts out of carrier power.
The picture of the O-scope is showing 10 volts per division...across my MFJ 50 ohm dummy load.

I have the IRF510 heatsinked to the copper board.

I will make a diagram with my layout and all...

check it out...
http://www.angelfire.com/de/RadioAnarchy/

7

The RF Workbench / Re: Measuring transmitters with an oscilloscope

« on: September 10, 2013, 1504 UTC »

several months ago, some rain water leaked through the roof and ceiling on to
my old B and K scope.. it blew out the high voltage circuit when I turned it on.
I had it for 20 years or more.

so I went on craigslist and found here in my area a Tektronix 465M for
225 bucks. . . this is the military version of the old famous 465B that I have
used back as a technician years ago, working at various places.
 both of these scopes were very
costly back then.

so you can get you an old analog CRT scope for cheap nowadays,
and they are good for RF.

that is how I learned, by reading books, and then going on the internet to learn,
then try to design, build, and look at the signal on the O-scope and blow stuff up.
.them IRF510 can just pop and smoke sometimes.

and the only book that really tells you how to design is

Solid State Design for the Radio Amateur - by Hayward    

and I have some other book "RF Circuit Design"  that is good also.

8

The RF Workbench / Re: A simple shortwave pirate transmitter build

« on: September 10, 2013, 1443 UTC »

"ff" - yes, I changed to a PNP transistor at the oscillator, to cut out a few parts.

so across L1 to ground the signal should go up to at least 5 or 6 V and then go
down below ground level about the same amount..  and it is a dirty signal waveform,
but it works. .

the way I test all this is to put a 47 to 100 Ohm   2 Watt resistor in the place
of where L2 is in circuit with the IRF510 drain.  and also disconnect the output network (L3), and
shunt capacitor (C5).   then you can see an almost square-wave across this resistor
going from ground to 12 volts.  the IRF510 just needs to be ON about half of the time.

with the circuit all together, for C5, from 470 to 1000 picoFarad is OK...  
you can take this part out, for another check,  but then there will be a big
flyback voltage spike up to 100 volts or so, and the internal protection Zener
diode will conduct. This will clip out positive going modulation.

and the output power, the load on the IRF510 drain is determined by L3 and C6.
so maybe lower C6 to 680 or 470, and play with L3.   add more turns then
spread them out.

I have never had any problems getting 10 watts or more output with this type of
circuit, the flyback mode circuit.  I just throw it together and it works.
I have made many like this.  I will build
another one as this circuit shows in the next few days or so.

also. measuring the output power... into a 50 Ohm dummy load.
and you have an oscilloscope.     look for about 25 to 27 volts going
in each direction (50 to 54 volts peak to peak)   that is around 6 to 7 Watts.

just some tips, in case somebody does not know.  
after all, this is a "Black Art"

.....

9

The RF Workbench / what power source and modulator used ? ?

« on: September 07, 2013, 1546 UTC »

.

so what power source is being used out there for your homebrew transmitters? ?

there was all this talk about keeping them run on 12 Volts so that a battery
can be used, and bcsting from out in the woods (or desert).....
and also most have an Astron 12 V supply, actually putting
out 13.8 V, so these can be used at home.

also, what is being used for a modulator out there ?  guitars amps ?
car stereo amp?  or homebrew ?  The TDA2003 circuit ?
winding your own modulation transformer.. ? ?

also you can use your laptop computer power supply.
they are usually at 18 volts, and can deliver a few amps.
and just about everybody out there has one of these.

I am asking, since I have a few series modulator circuits,
that needs some tweaking.  But it is basically a linear
power supply, that changes output voltage along
with the audio input, as well as regulated power for the
tx oscillator and modulator audio section.  So this is
the power source for the whole system.

So is there any interest in  this out there ?

.

10

The RF Workbench / Re: A simple shortwave pirate transmitter build

« on: September 06, 2013, 2107 UTC »

nope. do not know.  not much math involved.
Plus I have made so many different transmitters,
I just know what will work.

these class-E  switching transmitters are different.
still kinda an experiment.
Actully, when I first started making these with the
IRF510 back many years ago, I cound not figure out my
problems.  I did not know there was anything
called class-E amplifiers.  or G, or H.
After I learned that stuff, then I figured out
the problems I always have had. 

L4 does no matter, as long as it is over a certain amount.

L3 is determined experimentaly, to tune up.  there is really no
math formula for what this should be,

L2 does not matter, as long as it is in a certain range,
with a core that works for RF.   L2 stores the energy pulse
to be supplied, and smoothed out with C5, to the network of L3 / C6.

L1 was just made to have a high enough reactance for the oscillator circuit
to work.








 

11

The RF Workbench / Re: A simple shortwave pirate transmitter build

« on: September 06, 2013, 1937 UTC »

OK, cool "makeRF"

let us know.

I just updated and made a few more comments about
how to test it and tuning up.   

My prototype, as many, was just super-glued to a piece of
copper-clad board.  But this weekend I would like to  build
another, in a better way,  using them Radio Shack
mentioned parts.   

12

The RF Workbench / Re: A simple shortwave pirate transmitter build

« on: September 06, 2013, 0239 UTC »

OK, updated my drawing on my website this Thursday evening.
let's see if someone else can make it work!! ! !

make an AM transmitter, or a beacon out of it.

.

13

SDR - Software Defined Radio / SDR - NBFM, or DSB, AM synchronous demodulation ? ?

« on: September 04, 2013, 2125 UTC »

hey Y'all...

I never messed with any SDR.

But have seen all this "waterfall" stuff.

So do these SDR's receive, in the MW/SW bands:  FM ? 
can  go narrow band FM ?
 have AM synchronous detection?   SSB ? DSB ? ? .

I have some things to try here soon...    I have a DSB modulator circuit
in my head, that can be applied to any of these little transmitters.
yes that is Double sideband, both upper and lower, no carrier,
or a low level carrier can be inserted, for synchronous demodulation.
The sound quality should be good, since there is no bandpass
filter involved.   

also may try narrow band FM....  1 Khz deviation or so..

years ago on 7415 kHz FM mode (the usual 5 kHz deviation)
I received on my Yaesu 757
the long version of "Inna Gadda Da Vida"     

funny, on the amateur radio bands you can not experiment like this.
It is too much work, or way too technical for most of them guys.
And they complain.    "oooh, to much bandwith"  etc. etc. etc.
Remember, on the HAM bands, when you hear them old guys with their
old vacuum tube radios in AM mode, it does not mean they know anything!!

14

General Radio Discussion / Re: The mysterious Yosemite Sam radio transmission

« on: September 03, 2013, 2254 UTC »

Yes, I received this 75 meter DSB signal back then when I was living in Southern California.

I used the hear the HAMS talk about it and want to get it....  funny
Them CBer types that get their HAM licenses are like that.
the "radio police"

and I thought that they found this beacon  to be some US Gov contract employees
inside some secret compound, just playing around.

.

15

The RF Workbench / Re: TDA2003 has been obsoleted

« on: September 03, 2013, 0250 UTC »

yes, a very cool part indeed.  and the TDA2002 before it.

I just checked NTE Inc and they list the inventories of
the NTE1288 (same as TDA2003), and a few hundred available.

http://dilp.netcomponents.com/cgi-bin/nteinc.asp?partnumber1=NTE1288

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