My Old Yaesu FT-470

[n2ize]

Many many moons ago (1990 to be exact) I bought a Yaesu FT-470 Dual band Ht. For it's time it was a state of the art radio, had a lot of features, bells and whistles, modifications that could be performed, and, could function as a low power cross band repeater.

I got a heck of a lot of use out of it for several years and then one day the VHF RF Power Amp module blew out. It still received fine, still worked fine on 440/70 cm, but no real output on the 2 meter VHF side. At the time I took the radio apart to get an idea what is going to be involved in fixing it. I put the radio into a plastic bag, set it aside, lost interest in VHF/UHF and did nothing with it for the past 15 or so years.

I had a dream a week or so ago that I fixed it and got it working again. recently I figured, why not make that dream a reality.

How to approach this ? Well, I guess the first step would be to make sure that the radio still works at all and is worth me fixing it. First thing I need to do is replace the lithium wafer cell that is used for memory, CMOS function etc. If I can manage that successfully I guess the next step would be to run some power into the radio and see it it still powers up. if it powers up then the next step will be to make sure it is receiving on both bands and, if all looks good I guess I can check to make sure it still transmits on 70cm and, at very least oscillates on 2 meters.

If all the above check out okay then the next step is the tricky part. I need to track down a replacement RF power Amp module... desolder the old one from the circuit and solder in a new one. Guess I can maybe get it from Yaesu, although any suggestions are appreciated. That is not going to be easy as there are a lot of leads and I don't want to cause heat damage to the circuit board or the new module. I might also need to see if I can get a schematic and a service/repair manual for this radio as there may be some adjustment (bias adjustments, etc.) needed whence the new module is installed.

If all goes well then all I would need to do after that is to pack everything back into the case, screw it all together and it's done. Oh yeah... I'll have to order a new battery pack... the old NiCad pack is history. Maybe I can incorporate a pack that uses a more modern Lithium Ion or Lithium Polymer cells.

In any event this will be a nice fall project. Not that I'm a big vhf/uhf fan but it is a hand little radio to have around and also handy for monitoring the local fire freqs as well. Between this and the antenna project it will be my first foray back into this hobby in many many years.

[PA5COR]

Check the connections of the P.A. module, some solderings went loose or bad, might be all the problem there is.

I hope the old P.A. modules are still on the market, or else we all have to dig one up ;)

Good luck in your new quest for gaining back the electronics side of the hobby.

I salute you :)

[KG4CGC]

Cheers and Best of Luck all around.
If you do find that it is simple a solder issue, fine gauge magnet wire, tweezers, magnifying glasses and fine fine solder tip with a steady will be all you will need.
Someone posted how to build a hot air soldering iron on the cheap using an aquarium air pump and other household hardware store items along with the right airbrush tips. I would revisit this page if I could find it but you could put together a rough idea in your head I'm sure.

[n2ize]

The good news is that I found both the "operations manual" and the "service manual" for the FT470 online for free. So now all I need is the PA module and the lithium battery.

[NQ6U]

Someone posted how to build a hot air soldering iron on the cheap using an aquarium air pump and other household hardware store items along with the right airbrush tips. I would revisit this page if I could find it but you could put together a rough idea in your head I'm sure.

Here you go:

http://www.instructables.com/id/DIY-...dering-Iron-1/

[n2ize]

Check the connections of the P.A. module, some solderings went loose or bad, might be all the problem there is.

I hope the old P.A. modules are still on the market, or else we all have to dig one up ;)

Good luck in your new quest for gaining back the electronics side of the hobby.

I salute you :)

Thanks. I'll check for bad solder joints first. It's easy enough to do since the radio is already disassembled. it will also give me a chance to get the part number of the PA mod. I think it's LM-(something or other). Hopefully I'll be able to find one.

There's also another project on line. Find the short circuit in the plate supply of my Valiant.

[KG4CGC]

Here you go:

http://www.instructables.com/id/DIY-...dering-Iron-1/

Attachment 3577

[NQ6U]

I think I'm going to try making one myself; I have an old cheap-o 50 watt soldering iron that seems like it would be perfect for the conversion and an air pump I scavenged out of some weird thing so long ago that I can't even remember what it was.

[K7SGJ]

I think I'm going to try making one myself; I have an old cheap-o 50 watt soldering iron that seems like it would be perfect for the conversion and an air pump I scavenged out of some weird thing so long ago that I can't even remember what it was.

I wondered what happened to my iron lung.

[n2ize]

Well, I got the Lithium battery with solder tabs on order. Once I get that I can solder it in place, check the connections to the PA module, run some power into it and see if it fires up. If I still don;t get any output on the VHF side then I'll have to see about getting hold of a new PA module.

If the whole thing works then I'm going to need to replace the battery pack. I opened the pack to see what kind of shape the old nicads are in. The site wasn't pretty. 20 year old nicads that have been sitting around unused for so many years sure don't look too good.