Thursday 18 October 2018

FT-857D Squelch Fault

Some weeks ago, I noted a distinct lack of apparent activity on 2m FM. Now, this wasnt too unusual, as the band is sparsely populated around here anyway save for CB type tools with no respect for any form of operating standards using it as their own private free-band.

But eventually I noticed that although I couldnt hear anything, I could see high signal strength readings! This led me to discover that the squelch had failed!

Thanks to the information from VK4SN near Brisbane, as shown here http://vk4sn.com/ft857.aspx and my trusty old Marconi 2955, ive been able to correct this fault, or at least, relieve the symptoms!

Following the instructions given, I also found like VK4SN that my new firmware values were around 170, far higher than they were before!

For the time being, I will see how it goes in this state. At some point though I suppose I will have to lift the main board (didnt fancy doing that today!) and check Q1063 as indicated. I might wait until I have located a source of this transistor first!

3 comments:

electronicnoobblog said...

Hello,

I'm following Your blog ( i found there interesting things about Clansman radios).

I kindly ask You as more skilled person in that topic for a advice about RT-351 (PRC 351)

I found that many people are looking for way to disable 150Hz tone transmitted but i'm interested in opposite.
I would like enable requirement of 150Hz to unlock squelch on radio, is it possible to enforce it?

Right now it transmit 150Hz but it can be opened just from carrier without any tone presented, is there setting to switch from carrier squelch into tone?.

Regards

Zak The Rabbit said...

The 351 is designed that way so it can interwork with other NATO radios without the 150Hz tone. It does this by having an internal 160Hz tone generator that over-rides the tone detector.

If you look in the EMER, you should be able to find the control for the 160Hz tone level - turn this right down, so there is no 160Hz tone, and it should then only work when there is a 150Hz tone present on the received signal.

I havent tried this myself, but thats the theory

electronicnoobblog said...

Thank You for answer, You are right.
I managed to solve problem:
https://www.youtube.com/watch?v=pZMwyWGb_iA
regards