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Hi everyone,

I have owned my FT847 for a very long time, maybe 20 years. It is a UK version that has usually worked on 70Mhz, but has stopped putting any power out recently. The radio goes into TX on 4m, but does not put any power out (measured on a Bird meter so there may be mW.). The radio has the L5006 mod from??and worked fine for 10 years or more.

The radio works fine on 50MHz so I know the PA stages are not kaput. I have done a factory reset several times and do not know what to look at next. Can anyone give me any clues?

Thanks
Steve, M0BPQ

In message <[email protected]>, Steve Bunting M0BPQ <steve@...> writes

Hi everyone,

I have owned my FT847 for a very long time, maybe 20 years. It is a UK
version that has usually worked on 70Mhz, but has stopped putting any
power out recently. The radio goes into TX on 4m, but does not put any
power out (measured on a Bird meter so there may be mW.). The radio has
the L5006 mod from? worked fine for
10 years or more.

The radio works fine on 50MHz so I know the PA stages are not kaput. I
have done a factory reset several times and do not know what to look at
next. Can anyone give me any clues?

Thanks
Steve, M0BPQ

I assume it works on Rx.

Someone posted a decent set of schematics recently. On page 6/7 you can see a section where the HF path splits to 3 different filters . One section is 54 to 76MHz. See if the signal is getting through that. Check the two steering diodes 3015 and 3031 and if the control voltage is functioning at the junction of R3041 and R3046.

I've studied the circuits at great length as I'm trying to find out why mine isn't working on 21MHz ( works everywhere else) . I think mine is that the relevant band pass filter in the PA isn't switching in as it doesn't work on RX either. Sometime I'll get round to debugging it.

Good luck

Brian GM4DIJ
--
Brian Howie

Thanks Brian -top tip!

Hope to see you again on 70MHz soon
Steve, M0BPQ

Hi Brian,
I don't work 70MHz (yet!) but my ft847 stopped working on 7MHz. No TX or RX. A bit of digging later and I traced it to D3053 in the bpf. Replaced the pair in bpf 4 and it’s working a treat again. Many more years of life in the old box... Good luck with yours!
73 de Andy M0DEL?

In message <[email protected]>, Andy M0DEL <amlindley@...> writes

Hi Brian,
I don't work 70MHz (yet!) but my ft847 stopped working on 7MHz. No TX
or RX. A bit of digging later and I traced it to D3053 in the bpf.
Replaced the pair in bpf 4 and it’s working a treat again. Many more
years of life in the old box... Good luck with yours!
73 de Andy M0DEL?

Thanks

I'll have look at the 21MHz equivalent BPF7. I'm surprised a fault there stopped the TX from working. I ordered schotty equivalents to do the improvement mod, but I've not got round to it.



I had it apart yesterday to fit a battery holder for the CMOS memory.

73 Brian GM4DIJ
--
Brian Howie