Leaderboard

Got my hands on a TK -880 and in the process of programming it.

Quarterwave antennae on VHF and UHF were always highly recommended when I ran the radio shop. I could solve alot of problems when I took a gain antenna off and put that little 6" quarter whip on instead.

Nice find!! Balloon would work too.... Altitude is certainly king when it comes to higher freqs like VHF...

If you want to do an "in-band" repeater you will need two radios, a duplexer and a controller as the main components. You can buy a cheap UHF duplexer at this site. If you supply the two frequencies they will tune the filter at no extra cost. Also don't forget to get any N to whatever RF adapter you will need to connect to the radios and the antenna. www.409shop.com/409shop_shopcat.php?&usercat=4942 If you want to know how well these cheap Chinese duplexers work a guy did some testing on one here. http://www.repeater-builder.com/antenna/pdf/chinese-mobile-duplexer-measurements.pdf Then use a simple repeater controller like this one. https://radio-tone.com/product/rt-crc1-repater-controller-full-duplex/ I see ad's for the "Surecom" controllers but have read a lot of bad or poor reviews. The one above seems to be OK. Also don't forget to get the right radio interface cables with it.

Oops. I mistook the ' for a ". In the case of eight feet, the loss is minuscule like 0.8db. But, if there is no place for the coil it is probably a good idea to pay a bit extra to get the right length. BTW, UHF male connectors are among the easiest to attach on your own, if you were interested in having a whack at the cable on your own.

Any local radio shop should also be able to do the work of shortening the cable as well.

never thought about the drone but wanted to try this some day just for fun (Balloon Experiments with Amateur Radio) http://bear.sbszoo.com/

Yeah, I've heard them too, but in the past, nowadays MURS is pretty dead around where I live. I've done some data telemetry with packet radio, fun stuff... 2W with a good antenna will reach ridiculously far if placed at the right location... my record was 30 miles, but one of the radios was strapped to a drone... so I guess that doesn't count... G.

Very true, but the OP was posted in the Amateur Radio (Ham) section of the forums.

A couple of notes related to this discussion. #1 Frequency and wavelength are 2 ways of describing the same phenomena. The frequency (Hertz) equals the number of waves that pass a given point per second. A wavelength equals the distance between two successive wave crests or troughs. http://history.amazingspace.org/resources/explorations/groundup/lesson/glossary/glossary_terms/graphics/igt2_wvlngthfreq.gif Here is the formula that is used to convert between the two measurements: Freq is the Frequency in cycles per second C is the velocity factor 299,792,458 meters per second (the speed of light) λ represents wavelength in meters So, a single wave at 462.725mHz (GMRS Ch 22) is 0.648 meters long, and a 1/4 wave is 0.162 meters or 6.379 inches. As for your ground plane, for a 1/4 wave antenna, it should be a bit longer that 1/4 wave in all directions. The longer the better. But, anything over 1/4 wave is fine. However, for your purposes, if you have the antenna mounted well above you and keep the power low, which you should do anyway, you will do just fine for most communications with the roll-bar as a ground plane all by itself. If you want exact measurements, take a look at this site. Also note that for repeater use there is a 5mHz difference between your transmit and receive frequencies. That translates to around 0.03" for Ch 22. The main point here is, unless you are designing the antenna for a single simplex frequency, there will always be tradeoffs in length. For more information, take a look at this discussion on RadioReference As to the number of channels. First off, don't confuse the term GMRS Channel, which translates to an FCC designated frequency, with the numbers of channels offered by your radio. With the radios, the term channel refers to an assignment of a frequency and other relevant information to a position in the radio's internal programming list. On simple radios, that is a dial position. On radios with a display, it is usually shown on the display. Some radios even allow you to hide the internal channel number and, instead, assign a name. While it is true that there really is no such thing as a sub-channel You might consider a specific combination of channel (frequency) and PL/DPL audio management to be like a separate channel. That is, if you call home on ch 14 with a PL of 88.5 and call your friend on the same frequency but with a PL of 131.8, you could either assign one channel on your radio to GMRS Channel 14, and then change PL as needed from the front panel or microphone (if possible), or assign two separate channels on kourradio, one for each combination. So, that is why some users want radios with more than 22 channels. See the Wikipedia for more information.

I do something similar to RCM. I like 445.000 through 447.000, which is coordinated for auxiliary and control links, repeaters and simplex.

Thanks for the heads up. I'll check out 10 later today. I usually hang out around 28.450USB, or 29.000AM.