Transcript Noise Bridge

QRP for the Tightwad
Tony Fishpool
G4WIF / K4WIF
The Shack
No room inside
the house ?
- me neither.
Photos of cases
Case
from an
old
modem.
Photos of cases
Photos of
cases……
Norcal mini
ATU made
from PCB
stock.
Photos of cases
Photos of
cases.
Inside view
Antenna Tip 1.
Next time you
consider getting one
of these :-
Antenna Tip 1.
Consider one
of these :-
Probes
Some of the probes
G3MFJ shows in our
book.
Probes
But also consider the Accuprobe from Nortex…
www.kk5na.com/nortex.htm - this allows you to measure
very small voltage levels.
Accuprobe
-Input
levels: LOW range - 50 mV rms to 5V rms (usable to 20 mV)
HIGH range – 5 V rms to 35 V rms
-100 kHz to 30 MHz
$17 post paid – what a deal!
VE3DNL Marker Generator
Something to generate a
signal to poke up the front
end…
How about a marker
generator like the VE3DNL
marker generator.
Only $7.50 from Norcal
(www.norcalqrp.org).
VE3DNL Circuit
Attenuator
There are more designs than you can shake a
soldering iron at. Here’s one I built :-
Noise Bridge/Generator.
Noise Bridge/Generator.
At the point at which zener diode conduction begins it will
generate a considerable amount of noise. We can use this
to good effect once we’ve amplified it a bit.
The important thing is
getting the coil right.
Use a FT50-43 core or
similar from the
junkbox. Something
like 5 turns of trifilar
wound wire will suffice.
Noise Bridge/Generator.
Micro Henry Meter
A clever little circuit by Walter Farrar G3ESP. As described it
will show a dip on the meter for small inductors up to 10uH
The 2N2222
If you want a few watts extra then dip into your big
bag of cheap transistors instead of ordering an
expensive PA transistor. JA9MAT showed in Sprat
how he used 15 transistors to get 3.5 watts out.
Low Pass Filter
Money saving Tip! – Only make one - and use it on lots of
rigs!
Low Pass Filter
Low Pass Filter
Values:Band
C1, 4
(pF)
C2, 3
(pF)
L1, 3
(turns)
L2
(turns)
Core
Wire
(mm)
1.8
820
220
30
34
T50-2
0.32
3.5
470
1200
25
27
T37-2
0.38
7.0
270
680
19
21
T37-2
0.48
10.1
270
560
19
20
T37-6
0.48
14.0
180
390
19
17
T37-6
0.55
Making PCB’s
Simply don’t bother for “one-offs” - unless you want to wait
before you start building and like to mess around with
chemicals. Save a fortune on Ferric Chloride!
Take a simple wood drill
like this …..
And grind off one of the
cutting blades.
(in USA called “brad point bits”?)
Making PCB’s
Just use a punch or small hand held hobby drill to start a
pilot hole.
And “twirl it slowly
around.
You can make an
“island” when and
where you want one.
Making PCB’s
An example audio
amplifier made using
the modified drill.
Build everything in an Altoids tin!
W8DIZ Marker Generator
Build everything in an Altoids tin!
LTC 1799 Really Cheap Signal Generator.
Other containers
Antenna Tip 2. - Budget Antennas.
Buy one of these :-
And go here :www.cebik.com
And spend the next couple of years having fun!
Radios for under a Pound
Some of the 99 pence
radios….
Radios for under a Pound
And another..
Radios for under a Pound
And another..
Radios for under a Pound
They all seem to have the same insides….
Slightly more expensive
Then we turned our attention to a more expensive radio.
This time we were shelling out a whole £2.99 !
Sold by the UK store
“Superdrug” this radio
sported 10 short wave
bands as well as FM and
medium wave. The major
discovery was that the
display was actually a
frequency counter.
£2.99 Radio
Hans Summers patiently traced out the circuit.
£2.99 Radio
Here's a great
picture of
Dimitri Aguero
F4DYT with
his Superdrug
radio in the
French Alps.
Never walk past a “skip”
No “cost conscious”
qrp-er can pass one of
these.
In England they are
known as a “skip”.
It is in one of these that all
my birthdays came at
once.
I found a Spectrum
Analyser!
But how about one of these?
NJ-QRP Signal Quality Meter.
Provides a simple and
easy way to determine
how “clean” the
output of an oscillator,
amplifier or properly
adjusted transmitter
really is.
G3RJV Utility Receiver
George G3RJV
tries on Graham
G3MFJ’s new
Texas hat.
G3RJV Utility Receiver
Subtitle “at last a use for
those bloody DDS kits”!
George found that from
time to time the need arose
for a simple “test receiver”.
Shown: The new Norcal
FCC-2 DDS Kit.
G3RJV Utility Receiver
FT37-43 core. Windings 0.27 mm. 12 turns Trifilar.
Yet another
item of test
gear that will
fit into an
Altoids tin.
Eamon EI9GQ goes one step further
Double balanced mixer with low pass filter
EI9GQ filter testing method
470R
Noise
Source
Filter
on test
Mixer
Detector
Osc.
AF
Amp.
PC
EI9GQ filter testing method
Above a Yaesu Filter.
Below a homebrew filter.
Antenna Tip 3.
Insulators and pulleys - I don’t use them at all.
These little blocks
come in bags of
100 and cost a few
pounds.
I get them from our
equivalent of Home
Depot.
Antenna Tip 3.
They make great little
insulators.
You can use them as
light centre pieces too.
Antenna Tip 3.
I also use them as
pulleys.
Having no moving parts
they never snag.
GQRP Club
Don’t miss out on the fun!
What a
deal!

Keep an eye on GQRP-L

Join the club - $14 per year

You get four issues of SPRAT
www.gqrp.com
GQRP Club – Projects Under Development
All sorts of interesting and inexpensive chips to
experiment with.
The ICS 525 – about two quid each.
Any crystal input from 5 – 27 MHz for any output
up to 250 MHz.


Very Low Jitter.
Montreal Fox uses an ICS 525
Two Metre Fox Transmitter - http://tinyurl.com/ndh25
As does the G3ZOI ARDF Transmitter
http://tinyurl.com/n8gzr
G3ZOI ARDF Transmitter
Selecting the frequency
of the transmitter.
Solder pads
ICS 525 - programming
ICS 525 - programming
http://tinyurl.com/lrwwc
GQRP Club
Putting the “L” back into
SOLDER
Join Today!