building a repeater out of two Kenwood TK-880

[Steve]

Hello everyone!

 

i'm looking to integrate a Kenwood TK-880-1 ver2 with a repeater controller.... I'm about to pull the trigger on a pair or 880s and just wanted to do a bit more research before i do.   On some other models like TK-805D, there is a way to open it up and solder some connections for the rx tx, ptt, tone, gnd, etc. (see link below)  I can't seem to find anything on interfacing those.... wondering if the front RJ-11 would allow a custom cable?  I'm going to most likely order a NHRC-3.1 controller so I'll have to make a custom cable anyway.  

 

Parts include:

 

Kenwood TK-880-1 ver2 40 watt (or Kenwood TK-840-1 25watt) - both inside the GMRS band.

 

NHRC-3.1 repeater controller

NHRC-Squelch controller

 

to be figured out later:

antenna tuned for GMRS

duplexer tuned for my channel

cables

 

I could also go with TK-840 - because i can also get a good deal on a pair of those. 

 

or maybe an older TK-805D because i found detailed plans on how to build the interface cable here:

http://www.repeater-builder.com/kenwood/pdfs/tk-805-wiring.pdf

 

I was looking to stay away from the 805 and 840 because the volume and ch knobs wear out, and become noisy.  The 880 has a digital volume control and more features, so i think it would last longer, and i'd get more life out of it.  plus, its a bit higher powered, not that i need that high of power anytime soon.

 

any experience connecting the 880's or 840s to a controller?  I'm leaning more towards the 880s, for a few $ more, the version 2 gives me 40 watts.  but i'm not sure i need all that power, so i hope there is a lower 10 watt option for normal use.  the 880 is hard to find details on, but i'll keep looking!

 

Steve

 

yes, i'm GMRS licensed.

[Steve]

I found a wire harness cable for the TK-880 among other TK models...

 

Kenwood kct-19

 

http://www.kenwoodusa.com/Communications/Land_Mobile_Radio/Accessories/KCT-19

 

This should work.   I'm going to order the pair of TK-880 and a pair of these cables.   I'll have to build the other end of the custom cable to interface with the KCT-19 and the NHRC-3.1 controler.   I'll use a compatable connector end and make it so it all plugs in.

[zap]

Why waste a 200+ channel (trunkable) radio that can be programmed through the front face plate for repeater duty and narrowbands?

 

The difference between version 1 and version 2 isn't the power output, its the programming software. Ver 1 requires DOS, Ver 2 requires Windows.

 

The TK-880 is a 25W radio. The TK-880H is a 40W radio. (The heatsink on a H is longer than a non-H model).

 

Also, good luck finding that connector in stock. Very few people still have them, and they generally want $40+ a piece for them.

[Steve]

The way i see it, i was going to get an older 800 series, like 805D or 840 but I found a dealer that was getting rid of older radios and told me they bench tested them, and gave me 30 days to return.  For the price ($65 for radio only and $85 for radio, new mic, mounting kit) I went for the 880 from them becuase i felt it was fair and at least tested.    They tossed in the wire harness for $17 and no extra shipping. 

 

I'm looking into making the other cable myself after i see how the first one connects.   I got three radios in total.  The two for repeater will second as a bsae station at home, and the third will be for my car.    Having the tk-880 not only give mes all the extra features, (keeping me busy playing with it) but this is a portable and temperary rig (for now).   And i figured maybe if i found a good location, i would make it perminante with the NHRC 3.1 controler.  I'll get that controler and wire it up after a few weeks of playing with the tk radios.  Related info here: http://www.qsl.net/k0kn/projects.html#KWTK

 

I also did some research and found that version 2 also has (besides your windows based programming) extra caller ID features where you can program a name and PTT ID so it will display the name on the screen. Also other features like that.   Here's a link to versoin 2 features in a PDF broshure: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http%3A%2F%2Fwww.yankeecommunications.com%2FTK-780H_880H.pdf&ei=HahlVK-KOYOqNoCVgdAB&usg=AFQjCNFZ5C_oG-3U_RwH2g0lKlK1aIfzjg&sig2=WS_-QN5sErijLR7OLzclJw&bvm=bv.79142246,d.cWc

 

You're right, only the H is 40 watt... the version 2 is just a firmware update.  its still 25 watts.  that's plenty for what i need it for.  I might run it at 10 watts at fist just as i get my feet wet.

 

lastly... it CAN be programmed through the face plate, you hold down "D" while power up, and keep holding it for a few seconds, it goes into serivice mode.  I'll try it out when i get the radios next week.   I might not need the USB cable.   talk about a rip off, the OEM USB cable is over $100... and i can't find any confirmed reports of people using $10 cheap RJ11 to USB (with usb controler chip embedded into the plug) cable and have it work.

 

I dont see how i'm wasting the radio.   The cheaper i go, the older and harder to prgram the thing will be.    The only otehr way to go cheaper is to get a pair of Baofeng 888s  ($15 each) and program THEM and just tie them together with a hard line for now, then use the 3.1 controler later between them.   I'm not sure i can get all the pinouts i need, but it would be a step up from the "poor man's repeater" using the simplex repeater system.  

 

If i put this repeater up and leave it up (add to this mygmrs.com database) it will have the 3.1 controler, announcing itsself, etc.  But step one is getting the gear together, tested, range test, etc.  It will only be in operation a few hours over the weekends until i feel i have tested and played enough with it.  I will either sell the parts, or take it to the next level and get the controler for it, and keep wirting it up, maybe some backup batteries, etc.

 

Now to look for a bigger power supply... my 6 AMP at home wont cut it.  It draws 8 amp to talk.... so I'm thnking a 12 amp power supply would be enough.

 

If i run off batteries, 12 volt marine batteries, or golf cart batteries, i'm wondering about the operating voltage range.... how low can it go (how far down on the batteries will it go and still be able to run).  The service manual only says input voltage is 13.4 and nothing about a "operational range" such 11.5v - 15.5v or something like that.   at least if i knew i could go from 12.3 v to 11.2 v, that would allow me to use some of the batter, but i could use more of the battery if the operating voltage was closer to 10 or 10.5 volts.  (and depending on the battery)

 

Steve

[zap]

The 3.1 is probably a little over the top but it'll work (I'd go with a 2.1). MDC1200 (the call select/PTT ID) has been standard on most Kenwood, Icom, and Motorola radios since the 90's. The one thing to realize, MDC-1200 isn't a plug an ID in…its a define an address book (and has to be done on each radio). If you have 0021 programmed in as Bob on your radio but on you're friends 0021 is Bill…it'll display Bill on your friends and Bob on yours. MDC-1200 does allow for select calling though (that may or may not be a need). 

 

You don't actually need a controller to run those as a repeater. What you can do is build a crossover cable to go between the two radios similar to the way instructed here (though this is for Icom's). I've got an Icom F420 repeater running like that.

http://www.prestonmoore.com/repeater.html

 

If you wanted ID, I'd go with the above setup plus a Com-Spec ID-8. Just wire it up parallel to the cross-over. It'll ID for you, give a courtesy tone (letting the TOT in the radios time) and can be programmed for hang time. I do something very similar with Motorola's and the cheap $10 repeater cable. I uses a vacant pin to program PL disable so when the system ID's, it disable's the transmit PL.

 

You can buy the serial programming cable for around $15 online. A simple USB to RS-232 adapter is a good thing to have when you're dealing with older commercial radios (DOS has no definition of USB). You'll have to make sure two things are done before you can field program the radio.

a) There is a little 0 ohm resistor that has to be removed from the control head of the radio (this requires taking the radio apart and a little patience finding the right resistor)

you'll have to enable front panel programming in the software (all of my 880H's are version 1 so I couldn't tell you how to do it in the windows software)

[Steve]

wow, this is some great info...    let me address a few issues:

 

I def don’t need the ID feature, i know all the radios have to have the names programmed in, i think its more of a new feature to play with at this point.  I already tried it on my Baofeng and its very slow.  At the end of the transmission is the only place for it.  I just realized its not fast like the data burst.   I think it would get old fast.

 

TK-880 Version 2.0

I'm looking at the PDF again, (link above) and ANI PTT ID is def a normal feature, the "new" feature with a * next to it are:

(straight copy and paste from the brochure PDF)

 

 

 

Caller ID* decodes an incoming PTT ID and uses the
pre-stored ID List with alphanumeric name tags to identify the
caller in the radio’s LCD. This is available for fleet portables
and mobiles as well as base stations.

 

Caller ID Stack* stores (in volatile memory) the three most
recently received PTT IDs for recall and review, allowing a user
to check for missed voice calls.

 

Extended ID List Capacity (100*) allows a base station radio
to select up to 100 target fleet radios by nametag to send
FleetSync ® Selective Calls and Status Messages.  Fleet radios
can display up to 100 caller names upon decoding PTT ID’s,
(Caller ID enabled), Selective Calls, Status and Text Messages.

 

Extended Status Message List (50*) provides up to 50
pre-stored sixteen-character alphanumeric messages permitting
a base to send a larger variety of job task messages.  Fleet
radios can display and respond accordingly with complimentary
acknowledgements. Also, special reserved Emergency,
Emergency Man-down*, Emergency Mode Off *, Horn Alert
(mobiles)* and Radio Stun/Acknowledge/Resurrect statuses
are provided.

 

(1 FleetSync ® “Basic” dispatch features are available using just 80-Series mobile/portable fleet
radios and an 80-Series mobile base/control station.  More advanced FleetSync ®
dispatch systems may require the FleetSync ® Enhanced option and FleetSync ® -compatible
peripherals and/or software.)

 

 

I agree that the 3.1 is a little over the top, but its the lowest priced one that has the voice recording feature.  There is a "radio check" feature that i like where you DTMF a command and it will record what is hears next and repeat it back out.  it will also function as a simplex repeater.  So i think it gives me a lot of options.  At the end of the day, after i put all the time and money into this, what's a few $ more to get a good controller? 

 

in the MEANTIME, i dont "need" that controller as i get used to the GMRS and 25 watts in my area.  I think i will end up building that cross over cable.  I have a lot of DIY skills, but the one thing i dont have a lot of is time. (family of three young kids, work, etc.)

 

That Com-Spec ID-8 looks pretty cool.  I will double check the rules, I'm not sure if i need to ID if the repeater is only temporary, like for a few hours during a hunting trip, or camping, but if it requires an id, then i might as well build the 3.1 controller, spend the time on the wires, cables, and all that, and do it once. 

 

I do have to get a nice USB to RS-232.  I MIGHT have an old WinXP laptop with serial out. I'll have to look for that, see if it still works.

 

The whole "enable front panel programming via the software" is a crazy "chicken and egg" problem.... i would hope that the firmware defaults to "enabled" and allows the deployment tech to turn it off, and have it default back on when the unit is reset.   Otherwise, the barrier to get in is always going to be the stupid programming cable and software. 

 

Now about that link you sent....  the page by "Preston Moore, N5YIZ" Thats exactly what i'm trying to build!  I'm going to look around and see what Ideas i can use from that page, and maybe purchase that "double hight" radio holder.  It say it has battery backup connectors, maybe I can put that into a large carry box with everything i need.  I am going to have to be careful that it can get enough air circulation.  I've seen too many portable rigs in an ammo can with no air flow.  That's def bad.     I also noticed the fan in the back, with the NHRC3.1 i can connect the fan to the "fan controller" and have it kick on after every broadcast for x seconds then shut down.

 

so at this point, its a multi step project, each step of the way, i learn a bit more and adjust.    At this point, my unknowns are:

 

1. it seems (i'll have to double check the pin outs) that the cross over cable will have to reach inside the radio and connect to points inside, i can't do a RJ45 to RJ45.  Hmmm.  If i could, then i would sell the Kenwood kct-19 wire harness.     

 

2. can holding down the "D" while power up enable front panel programming? If not, i'll have to open it up and find that 0 ohm and/or enable it in software which will open a new seet of challenges mentioned above.

 

Thanks for all your advice.   If anyone else has anything to add, that would be great. 

[Steve]

just got the 880s radios in the mail today.... sure enough, holding down the "D" button did NOT enable programming.   You where right, I guess that guy's video showing the short cut was on a radio that was already "software enabled" ..... what about that zero ohm resister?  Does that have to be modified also to allow FPP.   

 

So now, i'll order the cable.  I found one on ebay for $17 at: http://www.ebay.com/itm/USB-Programming-cable-Kenwood-Mobile-KPG-46-radio-/350253626255?pt=LH_DefaultDomain_0&hash=item518cbe338f

 

then i can start programming.   Right now, the radios just come on with "Ch 3" on the screen.  none of the buttons do anything except beep.   its as if it was locked to that channel.  

 

here's the antenna i ordered.  I also got that in the mail today.  its nice.  I'll set it all up soon, i even have the silicone tape to keep the connection
waterproof.

http://www.ebay.com/itm/111492843918?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Guest spd641]

Steve,

I would not put much faith in that antenna.It is not designed for repeater use,all you have is a piece of ladder line in a PVC pipe.You need a quality antenna and height to accomplish what you wish to do.I know someone who tried to use the antenna you purchased after telling him it would not work for a repeater system.You antenna is the most important part of your system,when you go cheap on the antenna the entire set up suffers.

 

You can have a $1,000 repeater and a $50.00 antenna set up and you have a $50.00 repeater system,here is the listing with points in it that make it look good but has attributes in it that most people will probably look over.I did when I first read it. The statement saying it has a small foot print stands out and like my freinds he only get 3 miles at 50ft

 

 Designed by Dr. Ed Fong WB6IQN of Univ. of California (formally at Berkeley and presently at Santa Cruz - Silicon Valley).  It is US Patent 12/27,397.   This antenna offers +5dB gain over a ground plane and has no ground radials. It is only 4 feet tall.  Perfect for repeaters, backup repeaters, portable repeaters or base station.  This antenna was originally developed under a grant from AC Daugherty Inc. for a MESH network.It has a small foot print and therefore can withstand 150MPH winds.  It is basically a 2 element vertical phase collinear but with very low loss coupling elements.

 

I thought you may like to see this and this guy gets a grant to build something that would cost $20.00 to build yourself.IMO there is something wrong with that but we live in a world that sadly likes to take advantage of others but will give you all types of hype and sneak in a few words as to the way their products really work so they can say they told you about the product before you bought it...William

[Steve]

William, you might be right.   I def have time to work up to a better antenna, I just wanted something to get some testing in.  This is my learning experneice.  I go from family talk to ham, to building rigs, to playing with different antennas.  I'm going slow and learning as i go, having fun.   thank you for the advice.  I agree the antenna and cable are so very important.   I hope i can have my rig figured out by summer for my camping and hiking trips.  Thats where i'm going to bring it (the portable repeater) for a few days at a time.  I think this antenna will be good to play with around town with the kids, when i'm ready to drop $100+ (or whatever price seems right to me) on a good antenna, then i will at least have something to compare it to.   so i'm really trying to say that i think you're right, and i will def learn from this.  Thank you.   

 

oh wait, i just re-read this, and you're suggesting that i was tricked because it does say "small footprint" meaning doesn't reach very far, but yet, the wording was mixed in and used out of context?  hmmm.  i hope that's not true.

 

i will post more as i go.

[Steve]

naturally i will be looking for a good GMRS antenna i can use on my roof, and/or portable rig i can hang fro ma tree during camping trips, etc.

[zap]

The antenna you bought is of the J-Pole variety. J-Poles are non-ground plane dependent antennas. They were originally designed by the Germans to be drug behind Zeppelins. They also aren't very wideband antennas. J-Poles by design are +3 dBd gain. To fool most hams and those who really don't know much about antennas, many people put antenna gain in terms of dBi…which is in reference to a non-existant radiator in the real world. The +5 dB is really +5.21 dBi which is equal to +3 dBd.

 

The Ed Fong antenna is some form of 300 or 400Ω ladder line. They work okay, but they aren't the proper dimensions for a j-pole (a real j-pole needs about 3-4" of spacing between the 3/4 wave and 1/4 wave pieces). This narrow-ness between the two pieces can cause desense in a full duplex environment (in half duplex they work just fine). 

 

I've got one of these laying around…it was free so it gets used occasionally.

https://www.tessco.com/products/displayProductInfo.do?sku=89263&eventGroup=4&eventPage=1

 

My favorite portable repeater antennas are these.

http://www.wiscointl.com/decibel/dipoles/db404.htm

 

I know a few guys who have had these made for portable repeaters with the break down option found in some of his larger antennas.

http://www.jpole-antenna.com/shop/462-mhz-land-mobile-gmrs-j-pole-antenna/

[Steve]

thanks for these antenna tips.. overall, I want to work out all the kinks of this antenna system before next summer, meanining start small, and work my way up to a better antenna as i go.... each summer I take the family to the lake and there is a perfect spot at the very top of the hill,  i'm guessing hundreds of feet up above all the little hills and vallys.   it can see prob a mile or two in each direction accross the lake... i'd love to get this tuned well and help us use our family talk GMRS radios, as well as our other baofeng uv5r and 888s radios tuned to GMRS for some ship to shore and during hiking and running to the trading post for supplies.  Last year we could not go very far because of the trees, hills in the way, and we were on the bubble pack talkabouts... but with the repeater as high as it could be, and some better radios (and antennas) it should really make a big difference. 

 

as for the build, i'm still waiting for power cables, fuese, and the programming cable.  I did manage to get an old TK-840 with the accessory cable for $30 shipped. i knew waiting for a good deal would pay off.  now i can either use the 840 plus the 880 together, or move the cable over to my other 880 and use both.   I'm thinking i rather have the 2nd 880 as a base station and leave the 840+880 in the repeater box.  I dont know yet.

 

as for antennas, i'm testing from home to the kids's school... talk about to talk about wont reach more than a few blocks even on "high" which is 1 watt GMRS, then i went from talk about to the baofeng uv5r with 702 antenna and it went much further, but not quite to the school yet.  Then i just got a cheap dual band car mount antenna and i can now talk from home talk abou to car (uv5-r).   so i think once i put the antenna on the roof, i should make a clean signal to the school parking lot from home.   I'm alos seeing how just driving over small a hill with a 15 ft rise makes a big difference.

[Steve]

I secured a solar pannel (100w) and charge controler.  Working on the battery.  I might used an old deep cycle for now, and then replace it with a newer "solar" battery later, after I do some testing on runtime, etc.  

 

So now I’m thinking about building my interconnects. I want this to be modular, so i want to have the ability to plug two types of cables into these TK-880 radios (or any similar like TK-840) in two setups.    in both cases, i was going to use a Molex 15pin so i can easily dis-connect everything or swap out the parts later. 

 

The connector: 

http://www.molex.com/pdm_docs/sd/003091152_sd.pdf

found this at Fry's for $4.50 each set of male+female, plus $5 shipping.

 

• Setup 1: with a repeater controller for long term setup.  I was going to go from the 15 pin Molex to a project box, and put the repeater controller in the project box.  I can port the connectors and LED lights through that box, etc.  Powered by 10amp desktop ps, or solar battery.

 

• Setup 1a: as a desktop / repeater, the controller can hang in the back of the two radios if they are stacked vertically.  Powered by 10 amp desktop powersupply.

 

• Setup 2: with a cross-over cable (as i call it now) where the PTT out keys up the other radio and passes audio to it, so it would act as a range extender, for a day trip / hike, or just playing around with location and range.  Powered by a solar battery.

 

I think i can make a nice set of cables with heat shrink, solder the ends a little, etc.   For power, i was going to use the Anderson Power Poles, 15 amp for the controller and 30 amp for the radios. (the two main sizes)

 

I'm looking for feedback on the cable in terms of shielding the cable....  I was going to cut the ends off one of my many VGA cables and see if i can use the wires inside that cable, because i figured they would have some shielding around them.   

 

Shielding all the components seems to be an issue.   I was watching this video where the guy wraps all the components with tin foil, even the cables, to reduce the RF leaking back into the system.    This video shows the shielding needed on a simplex repeater, i imagine the interference would be worse with a duplex repeater.  I’m hoping that with the Kenwood TK-xxx radios, they will be built better and have less radiation.

https://www.youtube.com/watch?v=TUlX6xZXEU0

 

When ya'll build your repeaters, do you use shielded wires everywhere?   Should the project box for the controler also be shielded? Should i use a metal project box?

[Steve]

Controlers i'm looking at are:

 

Elektra 2000 / VZ

http://hamtronix.com.br/prestashop/product.php?id_product=60

 

NHRC 3.1

http://www.nhrc.net/nhrc-3.1/

 

things i like:

 

easy to install, wire terminals for easy hookup

easy to program with USB and windows os

lots of options to play with later

voice recording / ID

"audio testing" feature, will repeat back what you say

replay last message

option for simplex mode

alarm notce at end of tail (low battery)

 

Extras that would be cool later:

 

Intelligent Carrier-Activated Switch

Digital Audio Delay

Repeater with command port

[zap]

If you were concerned with power draw, the NHRC-µ would be the best option but it doesn't feature real stored speech. Both the Electra and 3.1 feature linking. I don't remember if the Electra can be programmed through a computer though. If size is a factor, the Electra is a bit bigger than the NHRC.

 

Easiest way to do the simplex thing, when you program your radios, program the receive radio with transmit inhibit on 467.XXX and the transmit radio as a simplex radio on the matching 462 pair. Then just plug a Kenwood mic into the transmit radio.

[Steve]

Easiest way to do the simplex thing, when you program your radios, program the receive radio with transmit inhibit on 467.XXX and the transmit radio as a simplex radio on the matching 462 pair. Then just plug a Kenwood mic into the transmit radio.

 

Can you explain that a different way?  you mean option 2 or if i want to use the controler as a simplex repeater in some other option?    At this point, i am just going to do some experimenting.

 

 

I just got the programming cable for the tk-880.   Wow, this radio has some nice audio.  The squelch cuts right off, very tight, there is no burst of "CRRRR!" at the end.  Its super clean.   So I wonder if that has intellient squelch, so when the signal is weak, it will leave it open a bit longer.

[zap]

Can you explain that a different way?  you mean option 2 or if i want to use the controler as a simplex repeater in some other option?    At this point, i am just going to do some experimenting.

 

 

I just got the programming cable for the tk-880.   Wow, this radio has some nice audio.  The squelch cuts right off, very tight, there is no burst of "CRRRR!" at the end.  Its super clean.   So I wonder if that has intellient squelch, so when the signal is weak, it will leave it open a bit longer.

 

Probably better squelch circuits than equipment you're used to. If you had PL set, then most commercial rigs default to only open squelch (regardless of how tight the setting is) if the proper tone is present.

 

If you want to operate a mobile based repeater as a simplex station (not repeater) just plug the output in both the RX and TX sections of the radio. Also works if you need console/dispatcher operation.

[Steve]

a brief update on repeater build. i got my roof antenna set up using the $40 jpole inside a PVC pipe from ebay, its about 10 ft off the top of my roofline.   i have been playing with range while connected to a tk-880 and using a UV-R and 888s handheld to test different areas around my neighborhood.

 

here's the antenna i'm using...

http://www.ebay.com/itm/UHF-Base-Repeater-Antenna-ham-70-cm-GMRS-FRS-commercial-5dB-gain-/121494313637?

 

the seller says "This antenna does not required a ground plane. It consist of 2 phase 1/2 lambda elements."

 

It seems that because i have a lot of hills, its hard to get a lot of distance.  if i drive west towards the woods, its all down hill, and the signal is clear and strong about 1/2 to 3/4 miles, but if i head south about 1 mile to the park, there are a lot of hills, maybe 100 ft of ups and downs all the way there...    The baofeng 888s radio can reach the home base station but too noisy to make out the voice.  The UV-5R with the after market nagoya 701 is able to get clean audio, but there is a lot of noise.   As i get closer to home, the noise level drops down and the voice is still there at the same level, but without all the hiss and noise in the bacground.

 

I found a local private repeater, found the owner, and asked permission, got permission and started to test with his GMRS repeater.  I dont know anything about the gear/antenna used yet, but at this point, i know its on either a water tower or a cell tower on a hill top right in town, you can see the cell tower from the park, but not from home where my base is, and def not from the woods to the west.  

 

What i'm surprized about is how clean and clear the signal can be when i go through the repeater using the same gear on my side.  Both 888s and UV-5r can get a nice clean noise free signal through the repeater from all areas that i've been testing from in town.  There is no difference at all that i can hear from the west woods, to home in the vally, to the park, when its through the repeater. 

 

So what i am trying to figure out is "what" exactly makes it sound so clear?  I'm guessing its 15% antenna, 5% radio gear and 80% location.... where do you put the resources to make it sound so clean and clear?  Maybe its more like 70% location, 25% antenna and 5% radio?  Do I have that formula right?

 

Maybe if i upgrade my antenna it will help, but only in the vally where I'm at, as going over the hills breaks the line of sight.... so i'm back to "location" being so very important. 

 

...

 

Another thing i was wondering about....  when i'm inside the vally from my home base station to hand held, its clean with more noise as i get further away, but as soon as i go over a hill and break the "line of sight" and start to drive down the other side of the hill, i suddenly get a lot of very loud crackling sounds, even if i am outside my car, standing still.  It sounds like someone is shaking the antenna connection causing loud cracklling and scratching sounds they are louder than the voice signal and it makes it hard to make out what the voice is saying.   I'm wondering what this is, maybe the signal passing through trees getting noise from the tress moving in the wind, etc.  Anyone know?

[Steve]

i'm wondering if I should i be looking to spend more on a better UHF antenna, maybe an antenna tuner to get the most out of it.  Maybe something like this:

http://www.ebay.com/itm/UHF-Base-Repeater-Antenna-Professional-/141506470434?pt=US_Radio_Comm_Antennas&hash=item20f2716222

 

 

also, i will add, my "feedline" is just some 50ft of RG8x straight into the Kenwood tk-880 radio.

[zap]

A couple of things. 

 

Hold off on that antenna. If the $97 buy now should give you an idea of the reserve. For that you can nearly look at new antennas. (I'll post some links below).

 

The RG-8X is not the best feed line to use, but it'll work. Attenuation at 450 MHz is about 4 dB per 100 ft. (Similar to RG-213). 1/2" hard line would be better but it's pricey. Attenuation at 450 MHz is 1.45 dB per 100 ft ( $2.69 /foot ) but the connectors are a little more expensive. 

 

When you're dealing with repeaters…site and antenna are the most important things. Then comes loss in feed line and connectors. Try and get as much stuff with N connectors as possible (less loss than UHF connectors).

 

Not all antennas are built equally. Some focus radiated energy above the horizon line of the antenna but that is only good if your antenna is sitting at the bottom of a valley and you're on the slopes. Antennas which radiate downwards work best for high places (look for antennas with counterpoises sloped downwards or none at all). 

 

Here's a small gain antenna for nearly the "buy now" price of that other.

http://www.hol4g.com/ac/product.aspx?number=CTC-BS450SN-C&p=190651&sc=3563

 

This one is another $50 more (if you have a Tessco account it's $157.85). I actually have one of these…not a bad little antenna.

https://www.tessco.com/products/displayProductInfo.do?sku=89263&eventGroup=4&eventPage=1

 

Here's another place to look. Personally I'd avoid antennas under $100.

http://www.theantennafarm.com/catalog/antennas-191/base-antennas-193/commercial-base-antennas-258/omni-directional-antennas-976/380-525-mhz-uhf-antennas-250/uhf-omni-directional-ant-1096/

[Steve]

thanks, this gives me more stuff to learn and read up on.  that NCG Comet CA-712EFC looks nice.

[zap]

I've got one somewhere…never have hooked it up or tested it. I'm not a fan of how it mounts though (see antennas mounted in a flimsy collar at the base of the antenna fold over all the time). Not a huge fan of Comet mobile antennas but I have a few and they do work as advertised.

 

You may want to do a little reading up on dB, path loss, and most importantly, dBi versus dBd.

Radio Mobile is a good program to test repeater performance based on location and what not.

[Steve]

I would love to try it out and do a side by side compare to what I have now.  I could mount it to my antenna mast and do the same range check.   Does it have N connectors?  I'd have to look into mounting something like that on the side of my roof where the gable vent is, and have it reach up a few feet over the roofline and then use a short 25 ft run of LMR-600 and put the radio closer.   Currently i need the 50 of the cheaper cable becuase i have to run it down my chimney and along the roof, down the side of the house and into my first floor window where my office is.  it just makes it. 

 

yeah, i have been meaning to read up on the difference between dbi and dbd. 

[Steve]

i think what i have now is good, i need to see what kind of use i'm going to get out of all this before i put more money into it. so far, it works around the areas i need it close to home.  not sure its worth the slippery slope of trying to get that extra few miles out of it at this point.

[JohnE]

rough portable coverage based on 3dBd antenna 25W w/1.5 dB line loss at 8M high

http://i1105.photobucket.com/albums/h358/erscom/maps/steve_zpsdc0dcc5e.jpg

[Ronsales]

I have a 880H-1 Ver.2 running on a radio tone controller as a repeater and a ed.fong antenna on my base vhf and uhf swr 1.2/1.3 uhf to 1.3/1.4 vhf across the band widths tuned. Have found this antenna even though it is in my attic to broad cast about 25 miles on vhf TK-780H-1 and hit the joliet repeater from the il/wi state line full quieting on GMRS.

ED is a electronic teacher at the college and i feel he is doing a good job by allowing his students to learn and design a

few antennas as a class project. He has stood behind his antennas as i had one with high swr's and he sent me another

right away to make up for the mistake.

Back to the repeater,  I paired it up with a sm50 motorola as a reciever but can put a 780vhf or 880uhf inline as a reciever

have done this testing last year. 50 watt duplexer to a station master uhf repeater antenna at 32ft to the base 44ft to the

tip. Would have good coverage range of about 50 miles or more if i had it on a hill top {:>) and I would quit trying to get

this thing on a tower at my house.

Trees at a height of 65 feet all around me so I am at a disadvantage, get yours up in clear airspace and you will hear

all the frs traffic in the area like i do. Very annoying they are transmitting without a GMRS license on anything but

channels 8 thru 14 where they are supposed to be.