ANTENNA STUFFS
 
 OPERATING TIPS AND TRICKS
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
ANTENNA STUFFS
 
Some general comments on antennas 
-   Analyze your antenna first. Use at least two different programs, if possible, to confirm the results.Better       10 hours on computer than an hour on the tower. 
-   No coax losses on HF bands are negligible (see table below)
-   No connector losses on HF bands are negligible
-   SWR alone does not explain antenna properties
There is a good reason to climb the tower if the initial SWR is 1:2. If the antenna shows a SWR of 1:1.3, leave it. Measure both impedance components, if possible, and use Smith chart to explain what is the matter.
  
Comments on Commercial Antennas 
Hams living within cities and urban lots are often unable to erect a tower with a regular Yagi or Quad. Experiments with wires may require a lot of space so many Hams "ending" with a multiband vertical antenna. Regardless of wide availability of many types of such antennas the answer to the question "what antenna should I buy" is not simple. 
Avoid a "no radial" vertical  
A multiband vertical is always shortened on some bands and is "full sized" mostly only on 28 MHz. A non radial type which does not count on the mirror image building up the virtual half of the radiator and seems then more shortened than a classic one using radials.   No radial. antennas may serve as emergency solution that has no access to the roof and must do all within own apartment... "Balcony Hams" may utilize advantages of such radiators using this antenna mounted on the balcony fence anchored to the wall by two non conducting ropes at angle of about 45 degrees. What a rocky way to the DX world! 
  
Tuning problems
  
Antenna manufacturers advertise their products as perfectly tuned, some providing tuning possibility by varying of the radiator length, rare exception are tunable traps (as I know the only is Hy-Gain DX-88). It is strongly recommended to obtain a detailed manual before antenna purchase. The resonant frequency is strongly dependent on the antenna environment and grounding system (radials). You may find SWR graphs for CW, low phone and high phone tuning. Tests confirmed that all antennas were pre-tuned to SSB band portions. If you hate SSB,  you may became disappointed with first results and tired with up-down procedure needed for proper adjustments to make it work on other modes
  
Summary:
Any antenna is pre-tuned to SSB band portions.
Do not attempt to adjust the antenna without a good impedance analyzer (MFJ-259B recommended). 
  

Cheap materials and poor fabrication  

When purchasing a new antenna, take a look at the parts. If you find sharp edges or the tubing full of metal scraps, you need a bit of power to assemble two parts together, it is a sign of poor fabrication. Do not be blamed with "famous" product mark, a well known manufacturer may produce a poorly fabricated model. 

Another problem is a cheap material used for construction. Some manufacturers using a thermoplastic material for trap coil forms. It may melt easily if applied power exceeding some 500-700 Watts (noted such problems on the Hy-Gain DX-88, do not be blamed if the traps looking very heavy - it is the gimmick plast only, inside you may find a coil wound of relatively thin wire and the encapsulated trap prevents any air exchange for sufficient cooling). If tubular capacitors used in traps, the dielectric insert may smoke up quickly if applied power exceeds the above mentioned level (noted such problems on the Cushcraft AP8-A). Select an antenna with heavy tubular air capacitors (without any plast dielectric insert). The capacitors should be well protected from moisture, dust and insects. 

Pay attention to the clamps and screws used - the hardware should be always made of stainless steel. If you plan to buy an expedition antenna, which should be assembled and disassembled many times, self-cutting screws may cause problems. 

Ensure yourself about availability and quality of manufacturer’s customer support. 

Remember that applying of the legal limit power may become an "infernal" test. If your life is too short for QRP, use antennas with heavy traps where is easy a replacement with Teflon custom made coil form. 

 
 
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Operating tips & tricks
 
Tune for lower pitch   Many operators tuning for a 800 Hz pitch which may correspond to default factory setting of many radios. After some years with headphones it may became uncomfortable regardless of the fact that the human ear is mostly sensitive on frequencies of 1 kHz. 
Try some 500 Hz pitch . The noise peak caused by narrow filters may seem not so sharp, your ears may became tired not so quickly and, finally, you may feel some 'additional selectivity'. This fact is very easy to explain - if you listen to two signals, one of 1000 Hz pitch, second of 1100 Hz, there is a difference of 10 %. At 500 Hz the same 100 Hz difference represents twice - 20%. Ask your physician about relationship of the ear sensitivity vs. frequency. 
Many of keen CW operators using a pitch of 400-500 Hz. Compare their receiving abilities to your (especially on low bands) and tune lower! 

Use RIT and XIT properly Increase your QSO probability with proper use of the RIT and XIT. You should feel yourself comfortable, mostly if you running high speed CW above 40 Wpm. This causes tuning to preferred pitch, but your radio tuning may produce not an optimal pitch at your QSO partner. You may feel that you are tuning a bit up or down. If you are listening to a QSO, tune the QSO partner to most comfortable pitch using RIT and switch from RIT to XIT. It should be now optimal for you and operator of the station you want to call. I am tuning to some 500 Hz pitch and my favorite XIT setting is -0.11 kHz on my Kenwood radio. 

Use AGC - fast or off AGC generally decreases receiver sensitivity. It matches RX sensitivity to incoming signal level but the game is about the strongest signal coming through the IF filter - the receiver sensitivity is matched to any strong signal, regardless of its desirability.  Any QRM decreases sensitivity and longer AGC time constant increases the time of inaudibility of the weak DX signal. 
In early 'tube' years some receivers have separate gain control for RF and IF stages. It allows the operator to adjust the gain accurately to the actual band situation. Some operators calling for this facility now, in the era of computer controlled and totally automated solid state rigs! They using the AGC ocassionally, mostly in local QSOs. If you work DX, try AGC off (CW) or AGC fast (SSB), you will be surprised how your receiver works! Of course, remember to adjust RF gain properly... 

Pay attention to headphones Try once to wear your headphones for 48 hours or longer. You may believe that good quality headphones is very important think. Obtain good quality stereo headphones with high dynamic range. The pads must be soft enough and should fit well to your head. You should have a very comfortable feel. Low cost 'communications headphones' may not have desired dynamic range and comfortability. The pads should provide a high degree of acoustic separation from the operating room noise. 
Casually you may need to pick up a very weak signal from the noise. A good tool may became the medical phonendoscope. Combine its membrane with a single good quality phone or small loudspeaker. You may be surprised what efficient noise filter is the phonendoscope tubing. No more need for an additional DSP! 
Once you obtained a stereo headphones you may utilize its stereo cabability. You may use it for two radio contesting - fed the left phone with audio from radio #1, the right one with audio of radio #2. A good trick is also a small switching box allowing a quick change radios/phones. Another good idea is to split the audio to two channels with low and high pass filters. You may get pseudo stereo effect which allows to 'locate' the desired signal in the 'space' (audio basis). Another useful trick is antiphase connection. Take a closer look onto your headphones, you should discover the indicated polarity (usually marked with a + sign or color dot). Headphones factory setting is mostly using common - (minus) lead of both phones connected to cable braid and + leads to the L/R 'hot' conductors. Revert connections at one phone to enable antiphase connection. Try this setting, you may get a subjective feeling that the audio source seems moved into your head and the signal flows from inside to your ears. In the case of bad feeling (some operators may became tired very quickly) return the connection to the original factory setting. 
 
 
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