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

[Mike Schatzberg]

Hello Noel:

The results should be the same on the 1000MP, Mark V, and Mark V Field.
Also, you can see below that it worked on the IC 756Pro II roofing filter
board as well.

You can find the original article explaining the mod here:
http://home.earthlink.net/~cherokeehillfarm/id2.html

73 and Happy DXing,

Mike
W2AJI




----- Original Message ----- 
From: "VE2FWW" <ve2fww at globetrotter.net>
To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Saturday, February 02, 2008 7:57 PM
Subject: Re: [1000mp] Improving IM3 DR with Mark V and Inrad Roofing Filter


> 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
> >
> >
> >
> >
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