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.

[gortex2]

As others stated, go with hardline/heliax. Depending on the length, have you tried a local radio shop? Lengths under 100-75 feet can be had pretty cheaply. 

 

I was told to steer away from LMF on another site, was some of the sagest advice I got

 

Ditto. check with some local radio shops. When i worked at a shop once a year we would chop it all up and scrap it for burgers ! Anything less than 50' is normally junk to them. 

[Steve]

I couldn't find any 1/2 inch hardline 50 to 60 feet ready to go with connectors without special ordering... while looking for hardline, i found a guy selling 75 feet of lmr400 for $50 so i just ordered that, figured it was good enough, it has N connectors on both ends...   if i end up finding a real site for this repeater, i will special order the exact length of hardline, but for now, this is just going from my roof to my home office / shack.    its a huge upgrade along with the new antenna and my range is limited by the fact that i'm inside a shadow.... i was only getting half a mile at most before with 75 ft of RG8x and Gary Fong antenna.   i'm in a really bad area, so its more of a toy to play around with now, until i i get it up on a hilll top, it wont really be that useful beyond my neighborhood.   i'd love to find a better home for it, but no one is interested, and there is no gmrs activity in my area, at all.  which might be a good thing.  i'm going to continue to test and learn as i go.   i'll use my only gary fong antenna for my portable rig with the two TK-880 radios, then i'll prob sell it if i dont use it.  basically the problem i have is that there is no one to talk to.  doens't matter how good my antenna is or feedline, no one is there to talk with.  maybe once its up and running, i will add it to the DB here, but its really not going to have much coverage since my house is down in a shadow area.  if i ever find a better spot, that would make it much more useful.

[Steve]

Ditto. check with some local radio shops. When i worked at a shop once a year we would chop it all up and scrap it for burgers ! Anything less than 50' is normally junk to them. 

i live in north jersey, i dont know of any local radio shops anymore, they all closed down, the ones i know of at least.  if anyone knows of any in north jersey, let me know. i'd love to go look around at one.

[Logan5]

how about 50 feet of RG213 ?  I might be able to cut that distance in half and use 25 or 30 feet if i move the radio into my bedroom closet and feed the line a different path.  http://www.amazon.com/MPD-Digital-rg213-50-pl259-Low-Loss-Connectors/dp/B004TBE17O/ref=sr_1_2?s=electronics&ie=UTF8&qid=1447099104&sr=1-2&keywords=RG213+50+feet

 

after looking at the losses....

 

http://www.w4rp.com/ref/coax.html

 

it seems LMR400 would be a lot better than RG213 .....

 

how about 30 or 40 feet of LMR600? - or 400....

 

I'm going to double check the length and order soon, anything is better then 75 feet of RG8X that I had.

I use 75 feet of LMR600 "is very stiff" but I am very happy with it.

[gortex2]

Northeast Communications

244 E. Union Turnpike Wharton, NJ 07885

[ldcarson]

I haven't started my own thread, but thought I would chime in anyway.  I have done something similar(Testing purposes)  I have 2 Kenwood Tk862-G radios and 2 Baofeng FP8HP.  I bought a chinese duplexor and a radiotone controller.  I original had it set up with the Baofeng, without the duplexor, I got about 3-4 miles with 2 HTs next to each (Problem with radio sensitivity)  I have already programmed up the 2 TK's, but am awaiting pl259- to - N connector adapters.  This will allow me to run them through the cavity duplexor and radiotone controller.  This was mostly designed as a test.  I also have a Motorola GM300 repeater, but it is in the states in a box awating me to come home and setup.   My antenna is a TRAM and I bought a seperate Jpole for testing. I am interested in adding the chinese duplexor and 2 Baofengs to a Pelican case that can be hoisted up into a tree and see what that range would give. 

[zap]

I haven't started my own thread, but thought I would chime in anyway.  I have done something similar(Testing purposes)  I have 2 Kenwood Tk862-G radios and 2 Baofeng FP8HP.  I bought a chinese duplexor and a radiotone controller.  I original had it set up with the Baofeng, without the duplexor, I got about 3-4 miles with 2 HTs next to each (Problem with radio sensitivity)  I have already programmed up the 2 TK's, but am awaiting pl259- to - N connector adapters.  This will allow me to run them through the cavity duplexor and radiotone controller.  This was mostly designed as a test.  I also have a Motorola GM300 repeater, but it is in the states in a box awating me to come home and setup.   My antenna is a TRAM and I bought a seperate Jpole for testing. I am interested in adding the chinese duplexor and 2 Baofengs to a Pelican case that can be hoisted up into a tree and see what that range would give. 

Using adapters for testing is fine...but you'll do better with UHF-N RG-142.

[NevadaBlue]

I haven't started my own thread, but thought I would chime in anyway.  I have done something similar(Testing purposes)  I have 2 Kenwood Tk862-G radios and 2 Baofeng FP8HP.  I bought a chinese duplexor and a radiotone controller.  I original had it set up with the Baofeng, without the duplexor, I got about 3-4 miles with 2 HTs next to each (Problem with radio sensitivity)  I have already programmed up the 2 TK's, but am awaiting pl259- to - N connector adapters.  This will allow me to run them through the cavity duplexor and radiotone controller.  This was mostly designed as a test.  I also have a Motorola GM300 repeater, but it is in the states in a box awating me to come home and setup.   My antenna is a TRAM and I bought a seperate Jpole for testing. I am interested in adding the chinese duplexor and 2 Baofengs to a Pelican case that can be hoisted up into a tree and see what that range would give.

 

I like this, please DO start a thread.

[WQOJ953]

I'm using 100 feet of LMR400 with no issues. I also have a ED Fong antenna that at first I thought was junk. I could not rx anything with it and tx was almost as bad. Swapped out the radio and all was fine. I've hit both GMRS and Ham repeaters at quite a distance, The GMRS repeater is 45 miles away on a relatively high mountain top and come in very clear, the ham repeater is 52 miles away and is noisy but readable.

 

I've had my repeater project on the back burner most of the summer. I dusted it off again last night and installed the KCT-19 cables in the two TK-880s I'm planning on using. I've also ordered a ID-O-Matic controller today. Once it shows up I'll get it programmed and hooked up. 

[zap]

I'm using 100 feet of LMR400 with no issues. I also have a ED Fong antenna that at first I thought was junk. I could not rx anything with it and tx was almost as bad. Swapped out the radio and all was fine. I've hit both GMRS and Ham repeaters at quite a distance, The GMRS repeater is 45 miles away on a relatively high mountain top and come in very clear, the ham repeater is 52 miles away and is noisy but readable.

 

I've had my repeater project on the back burner most of the summer. I dusted it off again last night and installed the KCT-19 cables in the two TK-880s I'm planning on using. I've also ordered a ID-O-Matic controller today. Once it shows up I'll get it programmed and hooked up. 

Nothing wrong with LMR400 in a half duplex environment. If you do some research online, you'll find guys complaining about noise in full duplex operation.

[Steve]

I'm using 100 feet of LMR400 with no issues. I also have a ED Fong antenna that at first I thought was junk. I could not rx anything with it and tx was almost as bad. Swapped out the radio and all was fine. I've hit both GMRS and Ham repeaters at quite a distance, The GMRS repeater is 45 miles away on a relatively high mountain top and come in very clear, the ham repeater is 52 miles away and is noisy but readable.

 

I've had my repeater project on the back burner most of the summer. I dusted it off again last night and installed the KCT-19 cables in the two TK-880s I'm planning on using. I've also ordered a ID-O-Matic controller today. Once it shows up I'll get it programmed and hooked up. 

 

good stuff... glad to hear about no issues with 100ft lmr400, i have 75feet about to go up this week with my new antenna Comet CA-712EFC.  I will see how that compares to the ed fong with 75 ft of RG8x .... hopefully a huge difference.

 

then the KCT-19 cables.... yes! I have both of my 880 w cables ready to go... i have the Elektra 2000VZ controller ready to go.... i was going to build a custom cable to connect the two kct19 cables with the controller.  that way, i can re use the controller for other radios later by just swapping out the custom cables.  i have the batterys and solar pannel ready to go.  i'm clearing room on the bench for this and hopefully over winter break, i will have it all set up.   I plan to use the ed fong antenna as a "go box" antenna and i'll most likely build the tx880s into a water proof box.  that's a challance also, keeping the radios cool inside a plastic box in the hot sun.  i was thinking of using a large bolt and heat sink through the plastic box so that the heat can make its way outside without letting air through.  like this:

 

http://diyaudioprojects.com/Testeq/Dummy-Speaker-Load/VHS-95-Heat-Sink.jpg

 

my setup will then consist of a base station or portable repeater, battery backup w solar power.  I hope that i can set it up to run off grid if needed, at this point, for no other reason than as a cool project.  Without a proper location, its very limited to less than 1 mile range due to my house being down inside a bowl.

[zap]

I'd dremel the box out smaller than the mounting holes of the heat sink. Drill the mounting holes through the box. Get an epoxy or silicone and run the edge (make sure to cover the mounting holes) then put the heat sink in place and pop rivet in place.

 

Then use some thermal paste to thermally bond the radio heat sink to the external sink. Just remember, steel if a poor conductor of heat compared to aluminum and then copper. So if the heat on the radio is aluminum, your heat sink needs to be either aluminum or copper to keep the heat flowing away from the PA.

 

Sent from my Venue 7 3730 using Tapatalk

[Steve]

alright.... i got the new antenna up and some lmr400 cable.... sounds so much better... in the areas that are "line of sight" it sounds much louder, the voice over the noise that is, and further with more nose than ever before.  However, in those shadow areas, still very bad, so it just goes to reinforce how important line of sight really is.   I only did a quick test around the neighborhood.  I think this setup is overkill for the range, that is- i can't get further because I'm literally down inside a shadow area from everyone else, so unless i find a new home, its very limited in use.  however, the goal of reaching my ex wife's house and the schools so the kids could talk to me is a success!  (each about 1 mile from home but over the hill on the other side of my hill) ht outside in the street from her place sounds very clean, no noise.  so from the 2nd floor the kids will have to trouble.  (this is all on the HT)  my location sucks.  i will be talking with the neighbors who live at the top of the hill, maybe one of them will be interested in letting me set up there, i'm sure i can cover the entire town if i can just go a few blocks up the hill to the top. 

 

so my repeater is on the air using my motorola gr1225.

 

next up:  finish building the portable repeater with my twin TK880 and custom controller and Chinese duplexer, and solar panel w battery backup.  i really have no use for this, i's just for fun at this point.    using a mobile mag mount, i'll be able to take it in my car, and drive around and play with locations to see how well i can repeat from hill tops and the such. there are hills everywhere.  If i park at the top of the hill, leave my car with a mobile antenna, i can test again from those spots and see if that improves the signal and if i can reach further than the 1 mile i am getting now.

[ASRM]

Steve

 

I did much like you, I wanted a system that would cover mobile from home to my place of work (parking lot) and the wife's (driveway of law office) as well as where we go for shopping and family visits. I haven't made it to the range, but hoping it works there. Portable wise I get 5 miles, I know what you mean on line of sight, I see hills between the repeater and my location, something I noticed is that next to the hill I will lose or be much in the noise, move about 1/2 a mile out and the signal then reaches (theres a name for the over shadow but it escapes me).

 

I am only 40 feet up with a Comet 172 and a Vertex repeater pushing about 38 watts past the duplexer with 1/2 heliax. Hoping summer will bring a tower (60-100 foot-have a plan on an old 100 foot Rohn free standing and a DB408 sitting unused at a concrete company) and fill in some holes and push the range an extra mile.

 

Kudos on your setup, having decent 2-way and get away from cell service was my goal, and the setup has been a dream of mine going on 3 years.

[Steve]

i'm back on this project... i started building the custom cables to go between the two TK880 radios and the controller.  Its slow going, i have everything on the bench and testing tonight.  I'm taking photos and will post an update when i have something to share.   

[Steve]

Northeast Communications

244 E. Union Turnpike Wharton, NJ 07885

thanks, adding to my notes, i will check into them later. do they have a storefront?  I'd love to find a local place where i can get parts and older commercial gear and service.  i found a great place in CA but shipping is a pain. 

[Steve]

I ran into my first issue....  

 

I wired everything up correctly as far as i know... the receive works fine, it receives the signal, triggers COR on the controller, i see the controller "receive" and then the LED for "Transmit" lights up as it should, but the radio is not transmitting.  I see that the controller is in fact outputting the proper PTT active low (5v and 0v) on the pin going to the Kenwood.    I even tied all grounds together, both radios, controllerand both connectors of the radios. 

 

I went PTT out on the repeater controller (pin 4) look at page 3 of the manual for controller:

http://www.hamtronix.com.br/e_images/ele_man26_us.pdf

 

to pin 8 on the kenwood TK-880's page 19 on the manual:

http://www.repeater-builder.com/kenwood/pdfs/tk-880-svc-man-rev-e.pdf

 

I'm using the KCT-19 cable.

 

so the radio is not behaving correctly when getting the ptt active low on TX.  I wonder if there is a software setting.  my next step is to load up the software and look for a setting to "allow tx via accessory cable" or something like that.

 

does anyone else have any ideas?  has anyone else been able to get a Kenwood TK-880 to tx?  

 

one other thing i can try is manually trying some other inputs on the kenwood. 

[zap]

Try manually jumping the PTT pin to ground on be Kenwood.

 

 

Sent from my iPhone using Tapatalk

[Steve]

good news! it was the software setting.... i configured the output "com2" for PTT in the advanced settings tab of the programming software.  a friend on facebook also mentioned it might be a software config when i posted this link on the GMRS group. 

 

so now it will TX correctly!  but i have the audio in wrong because it wont pass audio, and no repeater beep so i'm sure its the wrong pin between controller and TX radio.

 

it might be a week before i will have time to work on this again, but i will post as i make progress!

[Steve]

with some help from facebook,  i was able to get my repeater running 100% .... i had to move a 0 ohm jumper from R94 and install it at R24 to enable the Mic Input. Shown on page 20. that was a pain, because the jumper was just a surface mount thing. i had to pop it off with a knife then very carefully solder the smallest blob i could  get on R24 but it worked. 

 

i'm on the air! I have my repeater controller working and tones and levels are all set.  so far, the audio quality of the two dk880s is good, i tested levels to make sure simplex and through repeaters are the same, and you can't tell the difference now. I'm operating it through a dummy load on the bench. we'll see once i get it up on the air long range. my goal is to reach the school from home, but there is a small hill in the way. we'll see.

[Steve]

next up is getting it all assembled in a metal box to allow plenty of cooling, etc... then replacing my bad feedline and getting my antenna back up on the roof.  if i can reach the school great, if not, then i have to find a new home for this repeater with more elevation.  i'm going to use the good cable this time, maybe half inch and put the radio up closer to the antenna for a shorter feedline.  we'll see.

[Steve]

photos of the install so far....

 

 

 

 

 

 

 

 

 

 

 

 

screen shot windows 7

 

[Steve]

The antenna i'm using is:

 

http://www.cometantenna.com/land-mobile/base-antennas/uhf-antennas/

 

CA-712EFC

 

The Duplexer is just one of those $90 mobile ones i got from ebay, i am not sure if a $200 set of cans would make a difference if i'm running this at home, i understand that in a high RF site i would need / require it. 

[berkinet]

...The Duplexer is just one of those $90 mobile ones i got from ebay, i am not sure if a $200 set of cans would make a difference if i'm running this at home, i understand that in a high RF site i would need / require it.

We have a similar duplexer with a Motorola GR1225 installed on a residential roof along side a PV (solar) system. We were using the EIA audio filtering on the input (high pass) and adding PL back in on transmit. what we found was during very bright times of the day we were getting intermod coming back into the radio and holding up the repeater until the time-out-time (TOT) was reached. After changing coax (inside the box and the antenna feedline) and antenna, we have come to the conclusion the source if the signal is the PV and the intermod is being generated in the duplexer. The duplexer was well tuned by a pro so there is not much we can do except to add some cavities. Unfortunately, that is not economically feasible for the moment.

 

In our case, since athe PV noise was not interfering with actual signals, we addressed the problem (I.e. we didn't actually solve it) by changing the transmit PL We could have also just passed PL (flat mode audio) but that effectively defeated the hang-timer and "over beep."

 

YMMV

[n4gix]

The antenna i'm using is:

 

http://www.cometantenna.com/land-mobile/base-antennas/uhf-antennas/

 

Do yourself huge favor and slip an appropriate length of shrink tube over the middle joint on the antenna to provide a much better water seal.