Question : Dual Band Radios

[Raccoon]

Does anything special have to be done to receive/transmit with a Kenwood TW-4000A ? Does a Duplexer absolutly have to be there to operate it ? Or can it be used with just a 2 meter antenna hooked into the 2 meter coax connecter as a 2 meter rig until I get a duplexer ? I don't know much about dual band radios yet so I just have my 2 meter antenna hooked up to it without a duplexer ... I used an HT to identify on a local repeater , and even though the antenna was hooked up on the 2m coax connecter and the Kenwood was on the same frequency as the HT ... I didn't receive a signal on the Kenwood to show it was receiving . Also , I briefly keyed up with the Kenwood to identify on the same repeater and the Kenwood showed that it had modulation key-up but the HT and the repeater didn't hear it . I'm using a 2 meter J-Pole antenna (the guy that made it said it's good for both 2m/70cm operation) and the repeater that I'm testing on doesn't require a CTCSS tone and I have all the offsets set correctly . Is this radio broke or have I hooked something up wrong ?

 

[Guest]

You don't need a duplexer. Forget about that.

This radio requires a tone board (make sure it's installed) to decode and encode CTCSS / PL.

Remember your transmit frequency into a repeater is going to be 600 KHz higher or lower than the frequency you listen to the repeater on.

Example.

146.000 Transmit into repeater
146.600 Receive from repeater

Don't forget to make sure your CTCSS or PL tones are correct for ENCODE (transmit into repeater) and DECODE (receive from repeater).

 

[Raccoon]

The radio isn't working right at this point ... If I don't need a duplexer to simply operate one band or another then there must be a defect in the radio . I bought it on eBay and it was suppose to be in good shape . I don't know alot about dual band radios but even I figured I didn't need a duplexer to operate on one band or another ... I just wanted to make sure before shipping this back to it's original owner .

------------------------------------------------------------
The Things I've Done So Far :

I've tested this on a repeater that doesn't require tones ...

The offsets are set correctly ...

It's been tested on Simplex using an HT for listening with no transmit being heard by the HT or the Kenwood ...

The 2 meter antenna is connected to the 2 meter coax connecter on the back of the radio ...

SWR's are 1.2 , the antenna is good and so is the coax ...

A 20 amp Power Supply has been being used , more than enough power ...

When the mic is keyed the radios meter shows key up ...

When the squelch is turned down I hear static , so the speaker's working ...

When I key the Kenwood to identify it doesn't trip the repeater and when I identify with an HT the repeater does identify but the Kenwood doesn't receive it

I thought it should work as a 2 meter rig myself with a 2 meter antenna hooked to the 2 meter coax connecter without a Duplexer in between ... but not knowing much about dual banders I wanted to ask around first to make sure I wasn't messing something up .

 

[Guest]

Try a simplex frequency, 146.520, and see if you can talk back and forth to your handheld.

Also, try a 440 repeater with the other antenna port and see if that side works.

A duplexer allows you to transmit and receive at the exact same time on a single feedline and antenna. Like a repeater. You don't need one because you aren't doing both at the same time.

Some dual-band radios with cross-band repeat have a small cavity built in to the radio to allow this.

 

[C2]

I have the same radio and it works well without a duplexer. Just don't forget and key into an open. I put a dummy load on the unused port just to be safe.

What frequency are you on, what input is the repeater, and what polarity are you set to?

There was one other thing I'll have ponder for a while before I can remember.

 

[Raccoon]

 

[Raccoon]

181 ... I forgot to mention that I tested it on Simplex as well ... I'm sorry


C2 ... the repeater is 147.360 with a positive offset and it doesn't require tones to operate it .

Like I said though ... it does show a key up on the meter so I know it has audio because the meter moves with my voice , but it isn't tripping the repeater and it isn't receiveing the repeater when I trip it with the HT and on simplex it isn't hearing the HT ... and I keep it on 2 meters only and have made sure that I'm connected to the right one . I would really like to figure it out rather to send it back cause I really like this radio .

 

[Raccoon]

C2 ... since you own one of these I do have 1 question for you about it ... Where the tone encoder is installed into these radios I noticed a plug there ... mine currently doesn't have the tone encoder in it and I was wondering if this plug was for when the tone encoder gets installed , does it plug into the tone encoder ? I have one on order I'm just waiting for it's arrival ... I just wondered if the plug was to that or if maybe it was something that became unpluged in the shipping . Thanks

 

[Guest]

Well, do you have a SWR/Wattmeter for VHF/UHF? See if it has output power.

Even if the radio is on simplex and you have another radio right next to it, you STILL get nothing? No carrier or audio in the other radio's receive?

If you're sure is has output power, and you're sure it has audio, then I would start checking if it's on frequency.

 

[C2]

I will have to crack mine open and see. Mine has dip switches on the bottom and I've never taken the covers off.

I was curious what tone board you got?

I got 4 more hours before I'm cut loose.

 

[Captain Kilowatt]

181 ...
Like I said though ... it does show a key up on the meter so I know it has audio because the meter moves with my voice.......

What function is the meter reading? That radio transmits FM mode so there should be no movement whatsoever of the meter when you talk. :?:

 

[Raccoon]

C2 ... I found a Ham Operator that had a TU-4C , the same board that Kenwood had made for the dual band function of the TW-4000A .

 

[C2]

On the front panel, the Tone button needs to be set on or off if your using tone. Naturally, if the repeater is not using a tone, then it does not matter for TX.

I am not sure if the radio will "decode"

There is also a switch on teh bottom for MON...not sure what that one is for either?

I had the manual around here someplace too, but I cant find that. I'm sure this helps immensly

 

[SARGE]

dual band radio

Raccoon

I have one of these radios to ,had a hard time trying to work it and took it over to a friend of mine who is a ham and he got it working.He was able to sit me down and explain what was in the manual so i could understand it, bless him he is very understanding if you need a manual i will copy mine and send it to you if that will help, hope you get it worked out.

 

[novakor]

SARGE that is a above and beyond the call of duty
Raccoon there ya go, a manual goes a long way and it's free.
When all else fails read thy directions,it may help it may not but what do you have to lose. BTW i also did a little research for ya with no luck,sorry. Good luck.

73,Stu
CDX-288