Trouble with Kenwood TM-D710A

[m_lars]

It seems to send and receive, but with an swr of over 10:1 I tried measuring resistance as @M Rose did, rather than continuity, on the PL259 connector on the back and got none. Maybe I’m barking up the wrong tree. It just seems so wrong to have any continuity between the two. I guess I’ll order another antenna? If other Kenwoods have the same readings, it must be normal.

Way back when I set up my CB antenna I got similarly high results and found a short in my mount. That’s what made me immediately start looking for a short. I assumed it was the mount again, but was shocked when all the cables and mount tested OK and the radio seems to be the culprit.

 

[Ubiety]

I have never seen SWRs that high on my Kenwoods so I'd keep looking. Do you know that your SWR meter is working correctly? I am obviously not an EE or even close ;)
Wife wants attention, will try to take a look at my radios later in the day... @M Rose is gonna have to put on an "Electramicity for Dummies" course for me ;)

 

[M Rose]

It seems to send and receive, but with an swr of over 10:1 I tried measuring resistance as @M Rose did, rather than continuity, on the PL259 connector on the back and got none. Maybe I’m barking up the wrong tree. It just seems so wrong to have any continuity between the two. I guess I’ll order another antenna? If other Kenwoods have the same readings, it must be normal.

Way back when I set up my CB antenna I got similarly high results and found a short in my mount. That’s what made me immediately start looking for a short. I assumed it was the mount again, but was shocked when all the cables and mount tested OK and the radio seems to be the culprit.

Was none as in OL, or 0.00 ohms?

 

[m_lars]

Was none as in OL, or 0.00 ohms?

0.00 ohms

 

[m_lars]

I have never seen SWRs that high on my Kenwoods so I'd keep looking. Do you know that your SWR meter is working correctly? I am obviously not an EE or even close ;)
Wife wants attention, will try to take a look at my radios later in the day... @M Rose is gonna have to put on an "Electramicity for Dummies" course for me ;)

The swr meter is new to me also, so I guess it could be bad.

I know it’s apples and oranges, but when I had a short in my CB antenna mount I had similarly high readings swr readings. I have a hard time believing it isn’t an internal short in the radio.

 

[M Rose]

0.00 ohms

That’s not good... that’s not good... that’s direct short... it should have resistance between the center pin on the PL259 connector and the chassis... Not OL and definitely not 0.00 you have an internal direct short.

 

[M Rose]

The swr meter is new to me also, so I guess it could be bad.

I know it’s apples and oranges, but when I had a short in my CB antenna mount I had similarly high readings swr readings. I have a hard time believing it isn’t an internal short in the radio.

I have a hard time believing so as well

 

[J.W.]

I agree with Mike on the short. I just tested a radio and got a similar result. Last night I had it backwards (sorry gang old brain, out of warranty). You should have resistance between the center and the chassis.

 

[M Rose]

I agree with Mike on the short. I just tested a radio and got a similar result. Last night I had it backwards (sorry gang old brain, out of warranty). You should have resistance between the center and the chassis.

I know I am a new Ham, but I do have a little knowledge with electronics (specifically radio gear) I dabbled for several years with experimental radio equipment for RC aircraft. I bought a kit to build my own 20 channel controller running 2.4 GHz with a range of about 4 miles los. The antenna was soldered to my transmitter boards with integrated circuits with lots of capacitors, diodes, and resistors. The unwanted RF signals need to go somewhere, so they are directed to ground through filters to the chassis... that is why you ground the chassis and try to ground the chassis to the same point as the Coax Shielding.

 

[M Rose]

Here is the inside of an analog CB radio, but the same thing is done via chips, processors and such in modern 2 meeter radios

 

[M Rose]

The swr meter is new to me also, so I guess it could be bad.

I know it’s apples and oranges, but when I had a short in my CB antenna mount I had similarly high readings swr readings. I have a hard time believing it isn’t an internal short in the radio.

I got confirmation you radio is DOA. Continuity should be 35-50 M Ohms for your radio. 0.00 Ohms means dead short inside

 

[m_lars]

I got confirmation you radio is DOA. Continuity should be 35-50 M Ohms for your radio. 0.00 Ohms means dead short inside

Copy that. I kinda figured that would be the answer.

 

[m_lars]

Thanks all for the effort in getting to the bottoms of that!

 

[M Rose]

Thanks all for the effort in getting to the bottoms of that!

So now what does the eBay seller have to say?
can you send the radio into HRO for repairs?

 

[m_lars]

So now what does the eBay seller have to say?
can you send the radio into HRO for repairs?

I’m going to look into repairs. I’m still waiting to see what he does about it. I got it cheap enough that I won’t lose my shirt. It also came with a power supply I don’t need, so I’ll sell that off to offset the cost.

 

[M Rose]

I’m going to look into repairs. I’m still waiting to see what he does about it. I got it cheap enough that I won’t lose my shirt. It also came with a power supply I don’t need, so I’ll sell that off to offset the cost.

Any updates?

 

[m_lars]

Any updates?

I just dropped off the radio at Air Comm yesterday. They were suspicious of the cable and mount. I had my truck there so they came out and tested it and said it was fine. It should get looked at today since they had a 24 hour wait for anything dropped off in person. I’ll post up what they find when I hear back.

 

[M Rose]

I just dropped off the radio at Air Comm yesterday. They were suspicious of the cable and mount. I had my truck there so they came out and tested it and said it was fine. It should get looked at today since they had a 24 hour wait for anything dropped off in person. I’ll post up what they find when I hear back.

Funny how they can’t take your word that the radio is dead and they have to test the truck and coax again... I would love to hear what the problem is... the guys who helped at my end are also anxiously awaiting the results.

 

[m_lars]

Funny how they can’t take your word that the radio is dead and they have to test the truck and coax again... I would love to hear what the problem is... the guys who helped at my end are also anxiously awaiting the results.

Yeah, it wasn’t necessarily that they didn’t think there was a problem with the radio. There were 3 or 4 guys with not much to do when I was there. One of them said he’s seen problems with the cable, specifically the braid not making good connection when the connector is crimped on. I will do my best to not keep you hanging!

 

[M Rose]

Yeah, it wasn’t necessarily that they didn’t think there was a problem with the radio. There were 3 or 4 guys with not much to do when I was there. One of them said he’s seen problems with the cable, specifically the braid not making good connection when the connector is crimped on. I will do my best to not keep you hanging!

No I get it being a auto tech for 20 years, I seldom took the customers word for the problem... just because it would usually cost me and them more time and money... faster and cheaper to do my own diagnostics.