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1186
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eHam Forums / Elmers / Getting +12V on and off a run of coax
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on: June 01, 2007, 11:14:41 AM
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The name for the type device you want is a "Bias - T"
They are used in all sorts of applications such as for remote antenna switching, antenna mounted receiver preamp power, etc...
Bill
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1188
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eHam Forums / Elmers / 2M Beam Question
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on: May 26, 2007, 07:43:33 AM
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The driven element is the one the coax feedline connects to, and which normally has the tuning element for adjusting SWR. That is the 'backside' of the beam. The forward signal is shaped by the directors which you can recognize by the decreasing lengths.
You can also think of the beam as being roughly triangular or arrowhead shaped with the smallest elements pointing in the forward direction.
good luck! Bill
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1189
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eHam Forums / Elmers / RF affect on trees
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on: May 25, 2007, 06:21:07 AM
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Lets put it this way: Radio has been in continuous use for over 100 years now and nobody has noticed any affect on trees or other plant for frequencies below microwave. As long as you stay within the legal limitations of amateur operations you have a wide margin of safety for you and your plants. The Chinese Elm tree was introduced to the US because American Elms were decimated by Dutch Elm disease, a bacteria carried by bark beetles. Look for white stains coming from wet holes in the bark. Your local nursey can tell you if weather conditions have been stressing trees this year. Enough gardening. Get back on the air!  73, Bill |
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1193
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eHam Forums / Elmers / Why does the USB show lower freq than the carrier?
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on: April 30, 2007, 09:55:43 AM
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The reason is partly explained by the name SSB, Single SIDE BAND.
AM and FM both tune directly on the center or carrier frequency. LSB and USB side bands are found on either side of the center or carrier frequency. To be accurate, in SSB, the carrier and the opposite sideband are removed and never transmitted so we can't use them for actually tuning.
Military and older ham radios do not adjust for the sideband difference meaning the operator has to calculate the value for the "window" vs. the center center frequecy, by subtracting or adding 1.5 or 2.0 khz. Fortunately for us, most ham rigs today show the correct frequency if you are in the same mode, but not if you switch between AM - SSB or CW, nor between CW and USB, except for some of the newest digital radios.
So just look at your hand with three fingers side by side and think of CW & AM in the center frequency and LSB/USB 1.5khz on either side.
73, Bill
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1194
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eHam Forums / Elmers / TNC Ground Loop
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on: April 28, 2007, 08:50:21 AM
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One problem the older PK232MBX had was feedback thru the microphone connection. As I recall the best solution was to disconnect the mic when doing digital.
Good luck,
Bill
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1196
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eHam Forums / Elmers / Airborne repeaters
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on: April 23, 2007, 07:20:27 AM
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An additional thought. I think that you will find that with the antennas so close together that obtaining enough frequency isolation will be a challenge in a small package.
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1198
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eHam Forums / Elmers / Airborne repeaters
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on: April 22, 2007, 01:31:19 PM
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Regarding antennas, a simple wire whip bent back at say 45degrees is the most practical. They have been used on general aviation aircraft since the 1930's. Below 300 - 400kts I'm not sure drag is a significant problem, nor worth the additional weight penalty to create an airfoil shape. However, you may be able to find airfoil shaped rod at an RC model aircraft shop.
Good luck with your project.
73.
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1199
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eHam Forums / Elmers / Receiver vs. Transciever [LONG]
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on: April 15, 2007, 05:36:03 AM
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Interesting advice from your elmer. This is the first time in AGES I've seen someone advocating going back to separate tx/rx components. Unless you are just dying to have a high end receiver, I can't why anyone would want to hassle with separate components for operating.
I would disagree that an analog filtered transceiver is hands down better than the newer IF processed models. There has been a learning curve for the manufacturers since introduction, but I think that they have really begun to master the application with the latest models, e.g. 756ProIII. The payoff with the digital filtering is the wide flexibility to find just the right settings to overcome changing QRM and QRN conditions. With analog filtering you may be limited to five or six settings, and that's it. Digitil is endless.
The bigger issue is personal preference and operation. An analog filtered radio is never going to have much artifact and are relatively easy to operate. Well true, some ops never can master even the IF shift knob. If you don't like fiddling with controlls, or absolutely can't stand audio that might sound processed, then the digital radios might not be for you.
Good luck, enjoy the pleasure of researching and dreaming on a new radio!
Bill
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1200
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eHam Forums / Elmers / ts-430s clicking in recieve
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on: April 15, 2007, 05:11:43 AM
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Offhand, either on air or bench checks of good rx/tx are the first steps. Relays on the older radios can certainly be quite noticeable. You don't mention whether you have had this radio for a while and are familiar with its operation. After that would be to take the cover off and try to get your ear close to each relay while cycling the key. Safety precautions observed, of course. Don't reach or lean across the finals, keep one hand in your pocket. Better if you have a helper to key for you.
Good luck, and congratulations on the new ticket! See you on the air.
73, Bill
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