Noise Bridge

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QRP for the Tightwad
Tony Fishpool G4WIF / K4WIF
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The Shack
No room inside the house ? - me neither.
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Photos of cases

• Case from an old modem.

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Photos of cases

• Photos of cases
• Norcal mini ATU made from PCB stock.

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Photos of cases

• Photos of cases.
• Inside view

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Antenna Tip 1.

• Next time you consider getting one of these -

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Antenna Tip 1.

• Consider one of these -

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Probes

• Some of the probes G3MFJ shows in our book.

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Probes

• But also consider the Accuprobe from Nortex
• www.kk5na.com/nortex.htm - this allows you to
  measure very small voltage levels.

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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!

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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).

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VE3DNL Circuit
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Attenuator

• There are more designs than you can shake a
  soldering iron at. Heres one I built -

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Noise Bridge/Generator.
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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 weve
  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.
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Noise Bridge/Generator.
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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
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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.

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Low Pass Filter

• Money saving Tip! Only make one - and use it on
  lots of rigs!

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Low Pass Filter
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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
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Making PCBs

• Simply dont 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?)
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Making PCBs

• 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.
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Making PCBs
An example audio amplifier made using the
modified drill.
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Build everything in an Altoids tin!
W8DIZ Marker Generator
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Build everything in an Altoids tin!
LTC 1799 Really Cheap Signal Generator.
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Other containers
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Antenna Tip 2. - Budget Antennas.
Buy one of these -

• And go here -
• www.cebik.com
• And spend the next couple of years having fun!

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Radios for under a Pound

• Some of the 99 pence radios.

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Radios for under a Pound

• And another..

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Radios for under a Pound

• And another..

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Radios for under a Pound

• They all seem to have the same insides.

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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.
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2.99 Radio

• Hans Summers patiently traced out the circuit.

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2.99 Radio

• Here's a great picture of Dimitri Aguero F4DYT
  with his Superdrug radio in the French Alps.

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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!

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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. 
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G3RJV Utility Receiver

George G3RJV tries on Graham G3MFJs new Texas
hat.
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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.

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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.
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Eamon EI9GQ goes one step further
Double balanced mixer with low pass filter
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EI9GQ filter testing method
470R
Filter on test
Noise Source
Mixer Detector
AFAmp.
PC
Osc.
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EI9GQ filter testing method
Above a Yaesu Filter. Below a homebrew
filter.
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Antenna Tip 3.

• Insulators and pulleys - I dont 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.
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Antenna Tip 3.

• They make great little insulators.
• You can use them as light centre pieces too.

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Antenna Tip 3.

• I also use them as pulleys.
• Having no moving parts they never snag.

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GQRP Club
Dont miss out on the fun!

• Keep an eye on GQRP-L
• Join the club - 14 per year
• You get four issues of SPRAT

www.gqrp.com
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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.

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Montreal Fox uses an ICS 525
Two Metre Fox Transmitter - http//tinyurl.com/n
dh25
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As does the G3ZOI ARDF Transmitter

• http//tinyurl.com/n8gzr

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G3ZOI ARDF Transmitter
Selecting the frequency of the transmitter.
Solder pads
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ICS 525 - programming
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ICS 525 - programming
http//tinyurl.com/lrwwc
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GQRP Club
Putting the L back into SOLDER Join Today!