Icom 706 Finals Obsolete

[WA9FVP]

About two weeks ago I posted an article that
I snipped from mods.dk about the 706mkIIg finals
being obsolete. I did some investigating and
determined that the Icom is replacing the SRFJ7044
power FET with the RD70HVF, the same power FET that's
used in the Icom IC-2720 dual band.  If you check the
product reviews in eHam.net under;

Transceivers: VHF/UHF Base/Mobile (non hand-held)/
ICOM IC-2720H

You will see several complaints about finals burning
out in the IC-2720.

I hope that Icom isn't using the same finals in the
IC706MKIIG that are causing problems in 2720!!

Here a repeat of the article.
---------Snip--------

The 706MKIIG radio has 2 different versions of the PA
board. The older PA board's finals (1590002690)aka
(srfj7044) are no longer available and would require
replacement of the PA board. The newer style PA board
transistors are part# 1560001190 (rd70HVF) and can be
ordered by The 2 styles of transistors are not
interchangeable.

The complete PA board is part# 98413600 and sells for
apx $442. The catch 22 is that this board is the old
style board, with the old transistors. We do not have
the new style boards available yet so, if the finals
fail again, it's another board replacement.


Kevin McClinton, W7JRL
Technical Support Representative

ICOM America, Inc.
2380 116th Ave. NE
Bellevue, WA 98004
Ph. (425) 454-7619
Fax (425) 637-8417
www.icomamerica.com

---------Snip--------  
       

[W6VPS]

Here's a little additional info from MTS Radio Repair

http://www.angelfire.com/biz2/mts/

775(DSP)/706MKIIG Finals
These two, probably others, and any manuf. who used the J7004 MosFet for a final, have a terminal issue. The finals (SR(F or K)J7004(MP) are no longer available. I have tried to contact a few sources, and a couple of parts hunters.. no Stock, No availability. Supposedly ICOM has a way to use MRF140's to replace them. This is unconfirmed at this time, I will update this later if I can find out how, and if it is true. The PA in the MKIIG was changed about 2 years ago to a newer (totally different) device. Supposedly you can swap out PA units for about $800! hardly worth it. The 775(DSP) has had very few cases of Final failure, the 706 MKIIG has had more cases of it. Beware buying used MKIIG's, I have been unable so far to get a serial number cut off on the older MKIIG's. The newer final for the MKIIG I believe is the MRF 140MP. "UPDATE" the new final is the MRF140, and there is "unconfirmed" info that the MRF140 is a replacement for the J7004. The spec sheets say this can't be. The reactance and impeadence is quite a bit different between the two devices. At ICOM's price of $280 a pair, I won't be jumping in there to try and see what happens. As I find out more I will update this

[N6AJR]

I certainly trust Scotts judgement, he has done right on repairs for me several times.. thanks  Scott.

tom N6AJR

[WA9FVP]

The MRF 104's will probably replace the outputs
in the HF section but I don't think they will
work in the VHF/UHF side.

I don't it's fair to blame Icom for changes in the
design.  

It's motorola that discontinued the part and created
the shortage.  And while were on the subject,
Semiconductor surplus dealers are cut throat scum
bags that buy up all of the excess stock and inflate
the price so high that the part cost more the the
original equipment.

Jack
WA9FVP

[KJ7YL]

The Final change is not a fault of ICOM. The original transistor part number srfj7044 were manufactured by Motorola. Motorola decided to stop making this part and made it no longer availible.

The(rd70HVF)has a diffrent case style and does not physically fit on the board in place of the srfj7044. As a result the PA board had to be redesigned for the new transistor to be able to fit.

It will be interesting to see how this is worked out.