Yeasu FT757gx Wideband/MARS mod

how easy it to why band a 757?
dave

Hi Dave,

The Yaesu FT757gx is easy to wideband/MARS mod as it's simply a flick of a switch.....

However the switch is internal, buried behind the display circuit board and you have to be careful pulling the radio apart to gain access to it.

For details of the switch take a look at the following links :-


https://pa0fri.home.xs4all.nl/Mods/FT757GX/FT757GX%20restauration%20eng.htm

Half way down the pages you'll see a section marked 'Frequency Range' with a picture of the board disassembled from a radio but clearly showing the switch marked 'SO3'.


For a better view take a look at the following video :-

https://www.youtube.com/watch?v=X-M7fkYON4I


So easy enough to do but only once you've taken the radio apart. 

For that procedure it's best to look at the service manual and specifically the instructions for disassembly as well as the exploded view diagrams. 

The service manual can be found here :-

http://www.iw2nmx.it/Yaesu/FT-757GX/FT-757GX%20Service%20Manual.pdf


I'll give a couple of pointers/tips, remove the screws entirely including the easy to miss ones at the rear of the radio. It's helpful to remove the bottom casing first to assist in removing the top casing afterwards. 

When opening the top go slowly to make sure you disconnect the speaker connector at the front end of the radio so that you can flip over the top section containing the PA (power amplifier) and fan assembly. place a thick book or something at the back of the radio to assist flipping the PA section/top casing so that it has something to rest on and not pull at the interconnecting wiring.

From there the switch is easy enough to get to.

When reassembling be careful about placing the top PA section back down to prevent 'pinching' of the wiring at the rear end of the radio. (I've seen this as a 'fault' many times!) Don't forget to reconnect the speaker before closing down and make sure it sits aligned before putting the screws back on. The rear ones shouldn't be fiddly and if not aligned check again that the wiring hasn't got in the way.

Screw the cases down with the base screwed down last and job should be a good 'un.  

When powering the radio back on for the first time after that don't do the common mistake of leaving the 'MOX' switch pressed in as otherwise the radio will not switch on when pressing the power switch.

You'll be amazed how many have thought their radio was faulty after that little mistake!


So long as you take the radio apart carefully and reassemble just as carefully it's not the nightmare of a job it seems like.

I hope that helps Dave and I'll change the title of the posting to reflect the subject matter just in case anyone else finds it helpful in the future.


All the best,
Victor

thanks victor i knew you would known haven't brought it yet just really wanted to know how easy it was before i took the plunge 
regards
dave

No worries there Dave. 

After your success with your VFO encoder repair and veritable 'rig-doctor' skills you've now garnered I'm sure flicking the switch on an FT757 would be relatively easy.

I've still got mine, still opened, obviously only transmit on Ham frequencies ( ) and love the old girl.

73,
Victor

Another nice little mod for the 757 is variable power on SSB, Handy if you are running an amp and don't want to lower the mic gain. I did it to mine ages ago, Involves snipping a diode or resistor, Can't remember off the top of my head but if anyone is interested I will dig out my notes.

Hi Rich,

Yep, the SSB power mod is mentioned in the first link I provided under the heading "OUTPUT POWER CONTROL IN SSB".

73,
Victor

Ahhh so it is Victor. I have never seen that link but was told about the power mod from a friend of mine years ago. I saved that link as it looks very interesting. Love my 757GXII.