M-Tech MT-500 help please

[Andystart]

Hi all

I have just installed the above, which a friend gave me, powered up fine, fitted an new antenna, it transmits a real powerful signal, but it wont receive, (we checked this by calling on a mobile) am I doing something dumb, I don't have a manual so I have no set of instructions we used Ch 8 & 6 for testing

any help would be appreciated

 

[duncan99210]

User manual here https://www.manualslib.com/manual/886447/M-Tech-Mt-500.html?page=10#manual

 

[Andystart]

Thanks for the manual, but there is nothing in there pertaining to my problem

 

[MikeCC]

Recheck the antenna installation and all connections. If appropriate, solder core in to plugs. Get hold of an SWR meter and see that the apparent strong output really is so. Have you done a transmit/receive check with someone a few miles away?

If antenna installation OK and SWR checks out then probably something wrong with receive circuit.

SM Group in Plymouth were the UK distributors for that model which was discontinued a couple of years ago. May be able to do a repair but likely to cost halfway to a new radio.

 

[Andystart]

Thanks for response, yes did a check with a boat 3 miles away so I guess the antenna is ok

 

[rob2]

Have you checked that the set has selected "International" channel set as used in the UK? I believe in the USA channels 8 and 6 use different frequencies for ship and coastal stations, though a quick Google search was rather confusing with one table of frequencies showing different frequencies yet categorizing it as Simplex!

Obviously if the radio is on US channels it will transmit just fine, but you'll be on the wrong frequency to receive the reply. All the radios I've used have a button to select the channel set and an indicator on the screen to show which is selected.

Rob.

 

[Andystart]

thanks for the response, the LCD reads INT which I guess means I am on the international channel

 

[ithet]

I had similar symptoms on a radio, i.e. Tx checked out Ok but very poor reception. It did turn out to be the aerial connection.


Here is PDF manual:
https://www.marinepanservice.com/scarica/manuali/manuale-inglese-m-tech-mt-500.pdf

 

[Andystart]

Hi there, I have replaced the antenna and soldered the central core in, and it still doesn't receive, I have also tried a different radio, and the same issue, as a question, could it be possible that the set is not receiving enough power volts/amps ?

 

[rob2]

First reaction is No. It takes far less power to receive than transmit, so a low battery voltage or bad power connection usually allows the set to receive but not transmit. The fact that another radio showed the same symptoms still point to the antenna assembly as the most likely culprit. Worth checking the power leads anyway, it may prevent a future problem. If you can check the voltage at the radio whilst you're testing it should show if the voltage is being pulled down. I trust you replaced the co-ax cable when fitting the new aerial? It's always tempting to use the existing one rather than try to pull a new one through, but co-ax does degrade with age and moisture ingress and the impedance may no longer match the set.

Don't want to labour a point but you're sure the handheld was also on International channels? Whilst you show great consideration using ship-to-ship channels a very quick check on Ch 16 would eliminate any uncertainty (always simplex).

Rob.

 

[rob2]

Just a thought, but if I remember rightly you can plug an extension speaker into the set and this cuts out the internal speaker. There isn't a small jackplug in the back (just so it doesn't get lost)? That wouldn't explain the second set failing though...

Rob.