SCOPE MONITOR TECHNIQUES: TERRY'S TIPS (update 9/10/10)
  
The STATION MONITOR connection.
The VSWR on your SCOPE.
 If I have mentioned using a scope, I have not mentioned it enough. There are still more Amateur Radio operators out there running wide open with not possible way to see what their radio is actually doing...

For the sake of your equipment ant the life of your expensive radio...put a damn oscilloscope in your Ham Shack. It does not take rocket science to monitor your signal, tune up or watch your SSB output. In fact you probably have everything there in that junk box already.

All you need is a cheap 50 MHz or higher, dual trace scope that you can buy at any decent hamfest for less then $100.00. They are all over Ebay for a little more, or throw out a feeler on Craigslist...

 
  The Keep It Simple Scope (KISS) approach is always the easiest  to manage, but sometimes the hardest to grasp or understand.
In my hand is a GROUND PATH pickup. It is simply number 14 solid wire (enamel or insulated) and consists of 10 wraps over a 1/2 inch drill bit (chuck end). It is then insulated with shrink wrap and the two leads are fed to your scope's vertical input, obviously this is a simply secondary AIR transformer winding. You pass a piece of COAX through the loop, or mount it inside your TUNER next to the ANTENNA CAPACITOR. This is often called an RF sniffer and that is all you are really doing, sniffing for a little RF to monitor. You can accomplish the same thing with a simple 110 inch CB antenna mounted outside the shack. Bring in the COAX and plug  it directly into one of the two vertical inputs. There how simple was that ??


The pickup in my hand here is a T94 Torroid with 14 turns of 16 gauge wire. This is a CURRENT TRANSFORMER. If basically does the same thing as the AIR COIL except it will pickup a larger amount of RF and give you a much cleaner scope reading. The AIR coil is basically VOLTAGE TRANSFORMER, and it will pick up noise as well as RF signal, the CURRENT TRANSFORMER is capable of higher current so the sensitivity on your vertical input amplifier can be set lower and give you a greater range.
The torroid is sensitive at HF frequencies and does not carry those pesky white noise signals you see on the scope that is carried on between the actual frequencies you are monitoring.
The difference in these pickups is also different in the way they are used. You can pass your GROUND LEAD through this as shown below. A small piece of COAX terminated with a 10 or 20 PF disc cap and your ground system pickup is ready for use. This is almost so simple that it is hard to believe you
have not already done so...
Many oscilloscope users think the they need a lot of fancy boxes and expensive amplifiers to display the station operation. Those very hard to find, and expensive to buy station monitors are garbage when you do an along side comparison to a good scope. While those units have cool things like 1000 tone generators, you can do that with your computer these days, so why care if that is not part of your equipment line-up. Besides, most of those units are 10MHZ scopes, single channel and for the price of one you can have a 4 channel LAB SCOPE or a dual channel DIGITAL STORAGE unit by Tektronix.
Now that you get the idea, plug either of the above pickups directly into your vertical input. Start with about 50 WATTS in CW and you should be able to see the level on your scope. Adjust the VOLTS/DIV to a setting that will not drive off the scale when you double the power, your display should increase as well. Now try some SSB audio. You should see your audio and the SSB RF at the same time.

Anyway, check out the Oscilloscope 101 PDF file that is available on the DOWN LOAD PAGE...this is the perfect way to learn how to use a good scope.

There is a nice tutorial on RF transformers here: Read LONG WIRE BALUN and RF Transformers.

TERRY's TIPS: Well it ain't just about the monitor...catch this little goodie. The RADIO SHACK "snap chokes",    part number 2730105 and 2730069 are the least expensive way to insure that your unbalanced feed line is not  radiating in the shack. Coax line is considered the most popular feed-line used by the Amateur Radio hobbyist    today. Problem is the MIS-MATCH at the antenna. And unless you are DEAD NUTS ON resonant frequency,       there will be standing waves. These waves are like dropping a stone into a shallow pool of water. The waves    head out from the drop zone, strike the shore and bounce back. Eventually they disperse and the pool goes      silent. Now imagine a piece of coax looking at it on end...RF voltage travels along the outside surface of the    CENTER CONDUCTOR and on the inside surface of THE SHIELD BRAID. These waves are out of phase, if the      termination point (load) is correct, nothing is reflected, but if there is a mismatch, the reflected waves travel   back down on the outside surface of SHIELD BRAID. This is, in most cases, the gremlin that causes RF in your   shack and in your audio. This is generally the RF that gets into the phone, TV and computer speakers as well.   
Place two or three of the 2730105 chokes, depending on how much coax remains in the shack before it exits to the load...on the coax, just before it exits the shack. Place a pair on your coax jumper that feeds the amp.      These should be at the amplifier input. These chokes will lower if not eliminate the level of RF returning to the    shack. They also soften the currents that run along these lines on the OUTSIDE. The amplifier should not be     forgotten in this case because there are standing wave reflections from the input circuit as well.            K3HKR

THE VSWR on your SCOPE:


In the images above: DIODES ARE GERMANIUM: 1N34, 1N60 or BAV21 Diodes.
The RESISTORS are 51 ohms, 100 ohms or 1000 ohms depending on the METER used. The variable resistor (POT) is 10,000 ohms. The METER can be 50uA - 1000uA, depending on the range you require.
Remember that you must crank up the Volts/Division sensitivity (and lower the meter rating) if you increase R1,R2 above 100 ohm. These resistors have nothing to do with meter deflection, they are simply part of the load resistor for the diode.

Construction is simple. You can purchase the brass rods at any hobby shop that sells miniature railroad components. The standoff insulators that hold the tubes can be purchased with most all the other parts at your local Radio Shack (pre-punched perfboard). You may substitute BNC connectors, "N" connectors or PL-238 connectors for the coax connection. The components are 1/4 watt or 50VDC for the caps. Try to maintain the same lead length R-L when building the pickup. The length should be 6 - 8 inches long over all connector to connector. The pickups may be 20% shorter than the main tube. Keep the 1/2 inch space from the end on the DIODE connection for all dimensions. The tubes should be 1/8 to 3/16 away from the main tube. They must be matched equal distance from the main tube on both sides.
Remember to couple the SCOPE at the same point as the meter. The switch S2 allows you to select METER or SCOPE. This will allow you to switch between the meter and the scope for higher resolution. It may also be used as a tune up tool. Yes, the pickup can be built separate and those outputs can be connected to S1 inside a remote box with the meter face and scope connection.

Don't forget to read my other articles on using a scope. The SCOPE 101 tutorial page is available from the download page.

73,

K3HKR