AM filter mods for the Yaesu FT-840

[AudioShockwav]

This circuit From SP4HXS is a filter for AM, it replaces the crystal filter used in the YF-112A Yaesu FT-840.
You can build and install in the same location as the original, it requires adjustments in their inducing variables, which can be done manually.

73
Jeff

 

[edubro]

Hi Jeff:
Please, could you tell me what bandwidth you obtain with the filter you have made to replace the YF 112A of Yaesu FT 840?

 

[TonyV225]

Hiya Jeff!!, Ill tell you what, I have to of those Yaesu FT-840 they are great little easy to operaye Rigs!! They have a hotter receive than a person would think Ill tell ya that much. both of mine have the AM filters FM boards and one also has the TCXO-4 stabilizing Oscillator Crystal installed. Those FM boards and filters are not cheap!!! I see they are even more expensive now then they were back when I purchased them and installed them!! Those are great radios My first one was brandnew and an 11 meter guy in my area purchased it from AES in Milwaukee Wisconsin. He had it one week and sold it because he said he hated the receiver I got it and realized he most likely had no clue what he was doing with it or what a notch filter does because he lived right nextdorr to a Kwik Trip gas station and Im not sure what he was thinking but yeah all those striplights ETC that a gas station ran back in the early 2000's was gonna cause some havoc in a receiver but heck I couldn't pass up the price si I bought it and added the extras and loved the simple little thing so much that I purchased a second one and was going to give them to my two kids that are licensed but here they sit one need a resistor or diode replaced as the screen flashes but it was a common issue with the earlier runs of these FT-840 but once fixed there good as gold.

I had listed both mine and had interest but heard nothing back but there theres good rigs Excellent for a beginner or as a backup even for the advanced user. I figured the one needing part replacement would have sold as I was basically selling it for what I paid for the addons!! Part replacement and Waaahh Laaahh back up and running for someone!! The other works great I still get on 75 and 40 Meters with it just to run it!! I just hate seeing them sit and I been sick so I was just thinking about sending the second one out to Burghardt Amateur Repair Center for repair and just let them replace the part it keeps the PLL from locking in causing the screen to flash do to the PLL not locking in.Then Ill just jack the price up Im just shocked nobody jumped on the thing s I said I was selling it just for what I paid for the addons and didn't care about radio purchase price because I just wanted someone to get use out of it and not have to pay a lot for a nice HF rig.

One thing about these FT-840 they are the first HF Rig Ive delt with that you could plug an ASTATIC D104 Microphone in and just start talking and didn't have to mess with a bunch of settings they work great on AM and sounded goo there aswell Im not an AM user but got on 11 meters with both of them with a D104 and got great reports on both so I knew it wasn't a fluke thing. They are nice looking easy to use HF Rigs "anybody can run them" and worth the money with the filters the receivers are even better. Impressive radios for the money and that's why Yaesu made them aslong as they did. Ive got a later model and earlier model and they are the same radio all the way around only difference is that part replacement but once done there trouble free and it wont happen again.

 

[Mudfoot]

I've owned 2 840's in the past. Good radios, but not worth anything over $300 in great shape unless it has filters or FM board. Used to see them for a good price a few years ago, but they are crazy high now and nothing special about them deserves it.

 

[Retro CB Guy]

Hiya Jeff!!, Ill tell you what, I have to of those Yaesu FT-840 they are great little easy to operaye Rigs!! They have a hotter receive than a person would think Ill tell ya that much. both of mine have the AM filters FM boards and one also has the TCXO-4 stabilizing Oscillator Crystal installed. Those FM boards and filters are not cheap!!! I see they are even more expensive now then they were back when I purchased them and installed them!! Those are great radios My first one was brandnew and an 11 meter guy in my area purchased it from AES in Milwaukee Wisconsin. He had it one week and sold it because he said he hated the receiver I got it and realized he most likely had no clue what he was doing with it or what a notch filter does because he lived right nextdorr to a Kwik Trip gas station and Im not sure what he was thinking but yeah all those striplights ETC that a gas station ran back in the early 2000's was gonna cause some havoc in a receiver but heck I couldn't pass up the price si I bought it and added the extras and loved the simple little thing so much that I purchased a second one and was going to give them to my two kids that are licensed but here they sit one need a resistor or diode replaced as the screen flashes but it was a common issue with the earlier runs of these FT-840 but once fixed there good as gold.

I had listed both mine and had interest but heard nothing back but there theres good rigs Excellent for a beginner or as a backup even for the advanced user. I figured the one needing part replacement would have sold as I was basically selling it for what I paid for the addons!! Part replacement and Waaahh Laaahh back up and running for someone!! The other works great I still get on 75 and 40 Meters with it just to run it!! I just hate seeing them sit and I been sick so I was just thinking about sending the second one out to Burghardt Amateur Repair Center for repair and just let them replace the part it keeps the PLL from locking in causing the screen to flash do to the PLL not locking in.Then Ill just jack the price up Im just shocked nobody jumped on the thing s I said I was selling it just for what I paid for the addons and didn't care about radio purchase price because I just wanted someone to get use out of it and not have to pay a lot for a nice HF rig.

One thing about these FT-840 they are the first HF Rig Ive delt with that you could plug an ASTATIC D104 Microphone in and just start talking and didn't have to mess with a bunch of settings they work great on AM and sounded goo there aswell Im not an AM user but got on 11 meters with both of them with a D104 and got great reports on both so I knew it wasn't a fluke thing. They are nice looking easy to use HF Rigs "anybody can run them" and worth the money with the filters the receivers are even better. Impressive radios for the money and that's why Yaesu made them aslong as they did. Ive got a later model and earlier model and they are the same radio all the way around only difference is that part replacement but once done there trouble free and it wont happen again.

I'm looking for one of these yaesu ft 840 radio that you mentioned you have 2 of, could you part with one ?

Retro