[1000mp] Improving IM3 DR with Mark V and Inrad Roofing Filter

Sat Feb 2 20:10:15 EST 2008

What I find interesting is that the Kenwood TS850 seems to be a better radio than a stock FT1000MP and might be as good as the MP with all the mods.   I quess that is why I have the FT 1000MP sitting next to my TS850 and hardly ever it on.  A friend who is really into testing radios has told me time and time again that the FT 1000MP is a deaf radio.  Up until now I guess I really wasn't listening that good.  

Ron  WA0KDS

--- On Sat, 2/2/08, VE2FWW <ve2fww at globetrotter.net> wrote:

> From: VE2FWW <ve2fww at globetrotter.net>
> Subject: Re: [1000mp] Improving IM3 DR with Mark V and Inrad Roofing Filter
> To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
> Date: Saturday, February 2, 2008, 6:57 PM
> Very Interesting...
> Do you think the result will be the same with the MARK V
> Field...
> I have two of them, and I would like tu make the mod
> also..on the inrad
> boards
> Thanks
> NOEL
> ----- Original Message -----
> From: "Mike Schatzberg"
> <cherokeehillfarm at earthlink.net>
> To: "'All about Yaesu 1000mp'"
> <1000mp at mailman.qth.net>
> Sent: Sunday, February 03, 2008 00:06
> Subject: [AVIS-NOTICE] Re: [1000mp] Improving IM3 DR with
> Mark V and Inrad
> Roofing Filter
> 
> 
> > Hello 1000MP Fans:
> >
> > I wanted to update this thread with some additional
> information from
> Milan,
> > OK1VWK,  a member of OL7R multi contest team.  Milan
> has just recently
> > emailed me regarding his experiences with the W2AJI
> modifications for the
> > Mark V Inrad Roofing Filter Board.  He has given
> permission to post his
> > comments here on our 1000MP Reflector.
> >
> > There have been several questions lately regarding the
> mod.  I hope that
> > this will help a little towards answering them. 
> Perhaps W8JI will
> reinstall
> > the modified Inrad board, and make before and after
> mod data available.
> >
> > Milan has also made a photo available of the mod, the
> way he performed it,
> > using three parallel 470 ohm resistors for R6, as he
> did not have a 150
> ohm
> > resistor in his spare parts box.
> >
> > He goes on to say that his colleague, Mirek, OK1UFE, 
> tried to install the
> > IC756PRO2 Inrad Roofing Filter in an IC718, as they
> both have the same 1st
> > IF.  Mirek's data is presented in the
> correspondance below.
> >
> > 73 and Happy DXing,
> >
> > Mike
> > W2AJI
> >
> > Hi Mike,
> >
> > I would like to inform you about my experiments with
> Inrad roofing filter.
> > I have aplied your roofing filter IMD mod in my
> FT1000MP with good
> results.
> > It seems to be quite better than original solution
> from Inrad. I had big
> > problem with RX IM overload mainly on 40m. After
> reduction LNA gain, which
> > is installed on the roofing filter board is my RX more
> quiet than before.
> > No problem with space on 40m band now. No problem
> listen weak signal on
> > crowded band. I absolutely agree with your idea about
> this problem. I dont
> > understand why is Inrad still standing on the RSGB and
> ARRL measurements.
> >
> > There is some picture form my modification:
> >
> http://bp2.blogger.com/_JwUR_jrJq74/R4igQ71BB6I/AAAAAAAAAFE/X1i3xJ5X-nA/s160
> 0-h/ft1kroofing_mod1.jpg
> >
> http://bp2.blogger.com/_JwUR_jrJq74/R4il871BB7I/AAAAAAAAAFM/bX5eTh8QaTA/s160
> 0-h/ft1kroofing_mod2.jpg
> >
> > 73 de Milan, OK1VWK
> >
> >
> > Hello Mike,
> >
> > > I see that you used about 157 ohms, the parallel
> sum, by replacing R6
> with
> > three
> > > resistors.  Was this because you did not have a
> 150 ohm resistor?
> >
> > Absolutely right.
> >
> > > Did you test
> > > the 150 ohm verses the 157 ohm resistor and find
> a better solution?
> >
> > No, it was only my problem with R6 value and my spare
> parts for use. I
> > wanted to try your mod and I had 3x470 only, hi.
> >
> > > Several people have had big issues like you on 40
> meters,
> > > particularly during CW contests.
> >
> > It was terrible during last CQWWCW. I am member of
> OL7R contest team and
> we
> > had backup TRX TS850 also there. The TS850 seemed
> better than my FT1000MP
> > with Inrad roofing filter without your mod. I was
> thinking "It isnt normal
> > situation".
> >
> > > Maybe you know someone who could
> > > make the measurements?
> >
> > Grrr, thats problem. I am sorry but I dont have any
> idea now. But see text
> > below.
> >
> > My job coleague Mirek OK1UFE said to me, that he tried
> to install
> IC756PRO2
> > Inrad roofing filter into the IC718, because both TRXs
> have the same first
> > IF and why doesnt try it. After instalation Mirek
> measured original filter
> > loss and LNA gain . Filter loss was 2,5dB and LNA gain
> 6,5dB. He had to
> > reduce LNA gain and his new value is 1,7dB. I asked
> him if he aplied your
> > roofing filter IMD mod and he confirmed it. It seems
> that after your mod
> has
> > LNA 1,7dB gain. His roofing filter was purchased two
> or three months ago.
> >
> > Absolutely agree. LNA gain is designed for first VHF
> filter series with
> > highier loss than current production line and thats
> difference between
> ARRL
> > and RSGB test and real situation on the band. Inrad
> changed only filter
> loss
> > without LNA gain re-design. Inrad says highier filter
> LNA gain is good for
> > lower third IF gain. I think its total mistake. The
> major problem is total
> > radio system gain distribution on each IF. Inrad
> solution causes first IF
> > overload only and poor IMD results. Nothing else.
> >
> > > Would you mind if I share your results with our
> 1000MP Reflector
> members?
> >
> > Absolutely no problem. You may publish my info.
> >
> > Also thanks and nice to see you ...
> >
> > 73 de Milan,OK1VWK
> >
> >
> >
> >
> >
> ______________________________________________________________
> > 1000mp mailing list
> > Home: http://mailman.qth.net/mailman/listinfo/1000mp
> > Help: http://mailman.qth.net/mmfaq.html
> > Post: mailto:1000mp at mailman.qth.net
> 
> ______________________________________________________________
> 1000mp mailing list
> Home: http://mailman.qth.net/mailman/listinfo/1000mp
> Help: http://mailman.qth.net/mmfaq.html
> Post: mailto:1000mp at mailman.qth.net