ft847 on 4 metres

Questions and answers on 4 m transceivers, transverters, antennas, etc.

Postby G8HVY » Mon 20 Jun 2011, 20:41

Hi Bill
Have you put an SWR meter between the FT-847 and the amplifier as many
modern radio's will start to shut-down the power if the match is not good.

Best regards & GL

Graham
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HELP WITH PA1O

Postby 2E1HJS » Thu 27 Oct 2011, 12:27

can anyone tell me if my ft847 the serial number starts with 0c which i think is year 2000 will this radio mod using marks PA10 grateful for any help
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Postby MI0BDZ » Fri 28 Oct 2011, 00:00

Yes! Your radio can take all of the mods you are interested in. If it is a UK version (c2 on the box) then you only need to complete the rx bpf mods.

If you are only interested in the power mod then you can remove one capacitor from the PA board as shown on his PDF and also don`t forget to disconnect the "logic" transistor as mentioned many times before or the mod will not work. You will then see 80-90watts with perhaps 17 amps. A great improvement in efficiency.

However despite what many people say, the low pass filter will almost certainly soak up the extra power and will heat severely as its cutoff will likely be somewhere low in the 70mhz band. This results in the three inductors in the low pass filter heating so much that they (or one) will actually drop off the board.

Do not use this extra power unless you are able to modify the existing LPF or bypass the onboard low pass filter and of course use an external low pass filter if you dypass it. There are instructions on this forum, or download a free programme from the net and design your own LPF. It is really quite easy and interesting.



Mark (mi0bdz)
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PA1O MOD

Postby 2E1HJS » Sat 5 Nov 2011, 08:40

If i remove the cap for PAI0 mod does anyone know if these smd caps have to be 500 volts because i read on forum they are 500v or can they be less if ever need to replace one
GRATEFUL FOR ANY HELP
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Crispy L5022

Postby PA5M » Wed 25 Apr 2012, 22:26

2E1HJS, Roy

Did you ever manage to find the reason why L5022 was fried?
I got the same problem....

73e Michael
PA5M
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Postby MW0SGD » Tue 22 May 2012, 21:37

Hi all.
1st post so please be gentle. I have an 847 C2 04M95 serial prefix. I believe that makes it manufactured Nov 2004 production run 95. It is completely umodded - not even widebanded and it does TX on 4 meters giving 15 watts.
I am led to believe after reading a lot on the forum that Yaesu did improve the 4m capability of the rig as time went on so I was wondering which mods mine needed to being it up to scratch.
Any ideas / suggestions appreciated.

Thanks.
Simon
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Re: Crispy L5022

Postby 2E1HJS » Mon 16 Jul 2012, 09:11

PA5M wrote:2E1HJS, Roy

Did you ever manage to find the reason why L5022 was fried?
I got the same problem....

73e Michael
PA5M
yes i had swr problem on antenna i had to make a new inductor and now all ok if u need parts for making inductor i can help as i have the parts u need sorry i did not reply as i have not been on 4 meter forum for a while
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FT847 toroid problem

Postby PA5M » Tue 17 Jul 2012, 15:16

Hi Roy,

Sry for delay as I am working in the field and didn't ha much time for internet the last weeks.
Anyway my FT847 has been fixed.
The toroid has been replaced with an original one from Yaesu which took some time to get.
But all should be OK again.

My antenna situation wasn't that good too.
SWR has been 1.5-1.8 at times due to the close distance to the roof.
Now I have the antenna fixed into my mast in the garden where the SWR of course improved.

I am thinking about bypassing the internal BPF with an external one of the design as mentioned here: http://rudius.net/oz2m/70mhz/lpf.htm
This will allow more power going thru the external filter and hopefully keep the 847 intact.....

73e Michael
TU/PA5M
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Re: ft847 on 4 metres

Postby DH8VH » Sat 29 Jul 2017, 04:58

Hello,

sry 4 wakeup the old TH........
my question:
i have 2 FT847, ser no. start w. 8N17 and 1K54, witch is better to be modif. to 4m ?

best 73 & have a nice weekend
Teo
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Re: ft847 on 4 metres

Postby OH1ZAA » Tue 1 Aug 2017, 08:21

Hello Teo,

From Yaesu manufacturing code descriptions it could be that:

8N17... is from 1998 December and 1K54 from 2001 September

Personally I have not modified a FT-847 but I have understood
that the newer ones are easier to modify. Also I am not aware of
the exact total manufacturing period of this model. It seems that
in serial numbers C= January .... N= December.

My own FT-847 is a 8G07 - probably 1998 May - running on 70 MHz.

So maybe your best bet is to modify the 1K54-series FT-847 first.

Cheers/73, "Zaba" OH1ZAA (QRV under eight call signs in Finland)


P,S. Still a few weeks of 70 MHz Es ahead, so looking for you till August 31st.
So far a few dozen DL's worked on 70 MHz (mainly at OF3BCX/-4BCS/-5ZA).
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