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Author Topic: Kenwood TK-790H Commercial Radio for Ham Use  (Read 9651 times)
AC8MS
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Posts: 6




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« on: January 05, 2011, 09:40:43 PM »

 This summer I stopped at a yard sale with my wife. I saw two mics and a couple of radios with SO239s in a box along with some scrap home electronics. I paid ten dollars for the lot planning on scavenging the radios for parts. The box was put in a closet and forgotten about until a few days ago when my son said he was ready to get his license. I pulled out enough gear so he would have a functional shack to use as soon as he got his callsign. Among the things I gave him were the two Kenwood TK-790Hs with separation kits. He called me that night informing me that he had both of them powered up and weakly receiving one of the weather freqs on 162Mhz. As far as we can tell, we have two functioning radios.

   I have never worked with commercial radios on the ham bands before and would like to ask for opinions and advice on whether or not to invest in software/programming cables/ service manual. Is there a way to test these radios short of programming and going on the air? Are they just so Hell-For-Stout that if the lights come on it probably works? From what I have read, no physical mods are needed to get it to function on two meter, but it wont go below 145Mhz. Is that correct? Are there any programming quirks, firmware changes or anything of that nature we need to be aware of? Is there any internal alignment that calls for more than an SWR meter and multimeter? 

   Another thing I would to ask about is frequency agility. How well would one of these work for an interstate mobile rig? I've only had my license for a year now and have yet to go mobile outside my local area, but plan to. I would prefer having  access to all frequencies, but it seems to me that 254 channels would cover most of the voice channels on two meter. The manual refers to user selectable pl tones. It says only 16 tones are available in the field. In my area half the repeaters use 100hz. Will 16 pl tones cover the most common used? Would it be feasible to leave a computer connected to it (at least when using it as a base) to enter simplex/odd split/pl tones?

   I hope to make this a father and son project. Thank you for any information you can give us.
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K1CJS
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« Reply #1 on: January 06, 2011, 04:45:34 AM »

I see that you're speaking of two meter radios, but I've played around somewhat with a 70 cm Kenwood commercial radio.  I would venture to say that even if you can get them to work locally on two meters, they would not beat a regular two meter rig without being reworked.  The PL tone issue isn't an issue, but the frequency centering is.

With the '70 cm' commercial radio, there are three different models of the same radio, each covering different ranges of frequencies.  I believe that the same may be true of the 'two meter' type--that there may be at least two different frequency coverage ranges, and outside of those ranges the radios just will not work properly.

Internal alignment issues--the 'retuning'--will require more than just a multimeter, if it is able to be done at all.  Most of these radios are factory set through software programming with the parameters being locked into memory chips.  Any sort of a reset will clear any changes made and restore the factory settings.

You can NOT leave a computer connected to the rig since the programming cable is connected to the microphone jack for programming.  Also, 254 'channels' don't begin to cover the frequency selection possible for a ham rig.

In short, these commercial rigs are good if you want to set up a repeater system and can afford to have them reworked, but as mobile or base rigs, just get a regular two meter ham rig.  It'll be cheaper and you'll have fewer headaches than you would trying to get the commercial rigs to do what you want them to.
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AD6KA
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Posts: 2232




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« Reply #2 on: January 06, 2011, 06:53:01 AM »

I agree with the previous poster.
Nice find, but would be easier/cheaper to buy 2m ham band rigs.
But they're nice radios!

Here's a link to the brochures for the series:
http://www.kenwoodusa.com/UserFiles/File/UnitedStates/Communications/LMR/Brochures/TK-690_790_890.pdf

Website link to the radio:
http://www.kenwoodusa.com/Communications/Land_Mobile_Radio/Mobiles/TK-690-790-890

From the brochure, the 790H Type 1 covers 148-174 MHz,
the Type 2 (whatever THAT means) 136-156 MHz.

Channel spacing would make frequency agility very awkward to impossible
even if you COULD reprogram and use them: 12.5, 15, 25, and 30 KHz
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WA3SKN
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« Reply #3 on: January 06, 2011, 08:35:06 AM »

These probably could be set up for FM simplex use, but programming for repeater use could be a bear.  Programming the splits and CTCSS would be a challenge without the software, and the cost of the software probably would get a regular 2 meter rig.
73s.

-Mike.
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K5LXP
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« Reply #4 on: January 06, 2011, 11:03:44 AM »

I've got probably a dozen commercial radios I like and use regularly on ham radio, but a key factor is I have the programming software and interface hardware to do the programming.  If you don't have that, then there's little practical reason to invest any real money into using them.  Even if you found a shop or individual willing to program them for free, you would be bound to whatever you end up with, which by the nature of ham radio is bound to change (repeaters come and go, PL's change, etc).  I would consider just selling them and using the proceeds for a real ham radio.


Mark K5LXP
Albuquerque, NM
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VA3WXM
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Posts: 277




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« Reply #5 on: January 07, 2011, 03:14:11 PM »

I have a mix of commercial and ham gear.  My commercial gear is head and shoulders above the hammy stuff as far as RF performance both on receive and transmit is concerned.  Plus they're built like tanks.  The TK-790H is no exception (and it's a 110 watt with seven pounds of solid aluminum heatsink!)

Having said that, commercial gear isn't for everyone.  Number one is the programming challenges if you don't have the appropriate hardware and software.  Number two is frequency and PL/DPL agility.  The TK series somewhat addresses that by having so many channels and user-selectable tones.  It's still not the same as a VFO however.

A suggestion if the OP is not prepared to deal with these shortcomings would be to sell the radios.  The Kenwood 90 Series is a current-production model.  New list prices for a 790H + head + separation kit approaches $2000.  On the used market you could probably get $500-600 if everything is in working order.
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N6EY
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« Reply #6 on: January 07, 2011, 05:08:59 PM »

Having worked with these...yes, they can be programmed for HAM freqs and will generally work.

You CANNOT program them in any way without software and cables - simplex or otherwise.  The buttons are programmable per functions too, which is interesting, but it's a pain to remember what they do if you don't have the inserts.  Those are designed as public safety radios and are the workhorse of many agencies.  Great radios, and the H model is the high power version. 

As others have said, they're good radios, but they don't have a VFO control.  you'll have to program everything ahead of time.  If you choose to use them, program your nearby repeaters and the standard simplex frequencies, and have fun. 

Another choice might be to sell them and pick up a couple of dual band ham radios, but that's something you should decide for yourself.
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________________________________
73,
Jason N6EY
________________________________
K6LO
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Posts: 226




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« Reply #7 on: January 08, 2011, 06:55:22 AM »

The 790H K1 or K2 (look at our FCC ID sticker) will operate on 2 meters.  The K1 (148-174) may have trouble staying in lock near the 144 edge, but that is SSB territory and not a worry.  You absolutely will need the KPG44D programming software and cable.  Also if it is a California radio, it may have firmware cut specifically for CDF/OES (I wrote it,checksum 1C77, or A93D) and will require a special version of the KPG44D software (v1.11CDF for DOS of KPG44D "FS" for Windows) to program correctly.  Awesome radio, if I do say so myself, but despite that, and having many at my disposal, I am much happier with my TM-271A for 2 meter use.

73,

Luke
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AC8MS
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Posts: 6




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« Reply #8 on: January 08, 2011, 10:20:41 PM »

   I thank all of you for your information and advice. From what I can tell fair market value on these radios is around $400.00 used. Add another $150.00 for software/cable/manual. I wouldn't pay $550.00 for a somewhat limited 2 meter FM radio unless it made me sound like Walter Cronkite. But since I already have these radios, $150.00 for software/cable/manual breaks down to $75.00 per radio. That seems like a bargain for a rig that has the specs of the TK-790H, so we're putting them on the air as soon as we get what we need to program them.  I think it will suit me fine as a base station.

   I would like to ask a few  more questions:

 1) How does the signal quality compare to Motorola? A fellow ham has a Motorola desktop that has a better sound, both transmit and receive, than most ham rigs.
   
 2) I have the stock non-DTMF noise canceling microphones and would like to use a desk mike. Should I go with the KMC-9B or can I adapt a ham mic to the 12 pin connector on the 790?

 3) Is the programming cable something that a person with good computer skills could build, and if so, where can I find specs/schematic? Beside Kenwood and Ebay where can I buy a cable?

 4) There is a lot of activity around here between 152Mhz and 156Mhz.Should I plan on using a bandpass filter?

   It looks like my son's 1st radio will be a nice one.

73

Mark
   
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K6LO
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Posts: 226




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« Reply #9 on: January 09, 2011, 07:25:23 AM »

The cable is a simple level converter, however the radio connector is proprietary to KW and I have never found one on the open market.   Some of the old DOS software turns up on 'net searches from time.

The 90 series is high tier and is comparable to a Moto.  In fact many radios are these days. The 90 is the standard radio for the California Department of Forestry, OES, and the majority of public safety agencies in just about every county in the state.  Very popular nation wide.

You could adapt a ham mic.  There is nothing special about the 90 series microphone input. It will take a standard dynamic - 25mv @ 1K will have it bouncing off the ceiling.

It will not need a bandpass filter.

In your original post you had mentioned 254 channels.  Only some special firmware versions do.  Normally it is a 160 channel radio.  The special firmware versions are very tightly controlled and are unavailable - Japan has many lawyers. I did one for California, and I believe the Texas Rangers (cops not the team) and the Canadian Mounted Police have special versions with a higher count too.

Do you have the "full feature" control head (no speaker grill - more buttons, more display characters) or the one with the speaker built in?  Either one is fine.

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W7DOA
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Posts: 11




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« Reply #10 on: June 06, 2011, 09:07:21 AM »

I realize this is an older post but I just wanted to throw this out there. As some of the people here mentioned the TK-790's and not a good ham radio to have. So if you want to get rid of that old door stop let me know. I have a Kenwood door stop disposal service. I only do this for close friends but if you wanted to send me the radio I would be happy to dispose of it free of charge. Smiley

All joking aside. I have never felt having commercial gear is a hindrance. I program up what I want and put in a national simplex calling freq and call it good. As I travel I don't know anyone anyway and am not really the type of personal that likes to just rag chew on the radio with people I don't know. I know, I know, that's what ham radio is all about. If I get into a bind in a strange town and need assistance 146.520 will usually get someone who can help or can call someone who can. The user selectable tones are nice to have if you get to a position where you need different tones. The newer Kenwoods like the TK-7180's will program up the entire standard PL and DSC tables. And with 512 channel capacity you could program up a ton of repeater pairs and change tones on the fly.
Too bad there wasn't a way to take the ARRL repeater guide and pull the 512 most commonly used repeater pairs out. That would get you as close to VFO as possible with a commercial radio.
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KC0EUJ
Member

Posts: 3




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« Reply #11 on: September 10, 2013, 09:41:16 PM »

This summer I stopped at a yard sale with my wife. I saw two mics and a couple of radios with SO239s in a box along with some scrap home electronics. I paid ten dollars for the lot planning on scavenging the radios for parts. The box was put in a closet and forgotten about until a few days ago when my son said he was ready to get his license. I pulled out enough gear so he would have a functional shack to use as soon as he got his callsign. Among the things I gave him were the two Kenwood TK-790Hs with separation kits. He called me that night informing me that he had both of them powered up and weakly receiving one of the weather freqs on 162Mhz. As far as we can tell, we have two functioning radios.

   I have never worked with commercial radios on the ham bands before and would like to ask for opinions and advice on whether or not to invest in software/programming cables/ service manual. Is there a way to test these radios short of programming and going on the air? Are they just so Hell-For-Stout that if the lights come on it probably works? From what I have read, no physical mods are needed to get it to function on two meter, but it wont go below 145Mhz. Is that correct? Are there any programming quirks, firmware changes or anything of that nature we need to be aware of? Is there any internal alignment that calls for more than an SWR meter and multimeter? 

   Another thing I would to ask about is frequency agility. How well would one of these work for an interstate mobile rig? I've only had my license for a year now and have yet to go mobile outside my local area, but plan to. I would prefer having  access to all frequencies, but it seems to me that 254 channels would cover most of the voice channels on two meter. The manual refers to user selectable pl tones. It says only 16 tones are available in the field. In my area half the repeaters use 100hz. Will 16 pl tones cover the most common used? Would it be feasible to leave a computer connected to it (at least when using it as a base) to enter simplex/odd split/pl tones?

   I hope to make this a father and son project. Thank you for any information you can give us.
     




just had to throw this out there i run a tk-790 and a tk-830 both never had anything done to them both will out perform any 2m rig i have ever owned and i have had a bunch . my 790 has everything from 144 to 174  including  2m/police/fire/murs/marine it works flawless  . easy to program with the cable ./ the 830 is the same way 440 threw commercial uhf . works great run them both in my pickup . 
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