The Wireless Shack
RF Sniffer
	Perhaps it is a vanity thing but I like to be able to have a look at my transmitted waveform. Seriously, it is handy to be able to observe the RF envelope from a transmitter for several reasons. For example, it can tell you what your transmitted CW keying shape looks like, or what the effect of compression, or ALC,is having on your PEP transmissions. An RF sniffer is simply a device that couples a small amount of RF from a patch lead, and feeds that sample to an oscilloscope vertical channel. Of course you will need an oscilloscope to be able to use this little gadget. If you don't have one, then make it a top priority after a decent multi-meter, a 'scope is one of the first steps to expanding your horizons.

	Not strictly a circuit diagram. but I hope it shows the general idea. The patch lead, running from the output of a transmitter becomes a single winding through a toroidal transformer. The toroid has a secondary winding consisting of about 30t. A small sample of the signal present in the patch lead, is thus sampled and fed into an oscilloscope.
	First, wind your toroid. I used an Amidon T50-2. There are 30 turns of 24swg insulated wire wound around the toroid. This leaaves just enough room for the patch cable coax to pass through the centre.
	Trying to solder a 24swg conductor directly to the coax being used to send the sample to the 'scope looked a bit wobbly to me. So, I soldered the toroid onto a small scrap of veroboard, and connected the centre and screen of the RG58 directly to the copper strips underneath.
	Do you know what the housing is ? - It is, somewhat inevitably, a 20mm conduit T housing, with an inspection panel. The 'board' has been adhered to the housing with a couple of dabs of hot glue. You can see the main patch lead passing through the centre of the toroid.
	So now all that needs to be fitted as the connectors. For my HF station that meant a PL259 at the end of the main patch lead, and a BNC on the sampling line to connect to the 'scope. And that is pretty much it. To test the unit simply adjust the time base and Y attenuators on the 'scope and transmit into a dummy load. By adjustment of the timebase you will be able to see the transmitted envelope. You can of course leave this sniffer in place when transmitting into an aerial system - so no excuses no for rough looking SSB, or clicky CW. Nearly forgot - the coax cables are fed through holes drilled in 20mm conduit end caps. These can be a bit difficult to get hold of, but try your local electrical suppliers. Mine were .99p for 10 - and it makes a neat job.
Components - 20mm T Piece ( B&Q ), End Caps ( ES Electrical - Corsham ) , PL259 connectors - Farnell, BNC connector - Farnell, Coax - RG58 - Farnell, Toroid - T50-2 ( Sycom http://www.sycomcomp.co.uk/ supply them in small quantities - I order mine in bulk from AMIDON ) It should not prove at all difficult to obtain any of these parts - but I will make a basic kit available for £8.00 + £4.50 p&p..