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Re: [linrad] RE: H mode mixers at 144 MHz
Thanks for the interest in H-MIxers. I think they are the
most important thing to come along in mixers in a long time.
I first learned of H-Mixers in the ARRL Book "Experimental
Methods in RF Design". You probably remember when I posted
to this list on that book back in February or so. I think I
actually used an H-Mixer quote at that time, but I am not
The introduction to H-Mixers in that book is on page 5.15.
Other H-Mixer references and High-Level Mixer references by
I7SEX that I have or have copies of include:
This April (2003) RadCom [Technical Topics], where I7SWX's
design is discussed, page 82
RadCom July 1998 TT
Radcom August 1998 TT
Radcom September 1998 TT "Constructional Details"
Radcom January 1996 TT
Radcom February 1994 TT
Radcom October 1993 TT G3SBI's H-Mode Mixer description
Radcom March 1973 TT [I do not have a copy] Ed Oxley KB6QJ's
article using 4 J310's
Technical Topics Scrapbook 1995-1999 pp 72-73, 226, 231,
Technical Topics Scrapbook 1990-1994 pp 230-231 [G3SBI's
To get full advantage of the performance offered by the
H-Mode mixers you should of course have a very low phase
noise oscillators. Leif is working on these with excellent
Radcom July 1994 TT had a three page article on low noise
oscillators by G3SBI using a U310 and a stripline. This
also appears in the Technical Topics Scrapbook 1990=1994 pp
I had a web page or two archived [I thought] but I cannot
find them now ;(
The above information makes the web pages I had superfluous
in any case.
RadCom's Tecnical Topics is a wonderful, high level [for me]
discussion of all sorts of techical topics. I joined the
RSGB and get RadCom just to read it. The 'scrapbooks' have
all of the columns back to 1990. They are a wonderful
source of information. I recommend them to all!
I hope the above is helpful.
They are called H-Mode mixers because when they are drawn a
certain way the transformer configurations look like H's if
I recall correctly. The main thing about them is that the
FET's are GROUNDED.
I am sending a copy of this to Giancarlo, and also inviting
him to join the Linrad list as I think many of you would
like to hear directly from him.
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----- Original Message Follows -----
> Hi Roger,
> Thanks for the very interesting post.
> I wonder if there is any website of Giancarlo I7SWX and/or
> G3SBI? I have searched in Mr. Google but couldn't reach
> Who gave the name of "H-Mode Mixer"?
> Do you or Giancarlo know of any good webpage to learn
> H-Mode Mixer?
> Kohjin - JR1EDE
> At 21:31 03/05/31 -0400, you wrote:
> >Hi, Leif!
> >H-Mode mixers were made with J310's before people started
> >using the Fairchild devices, I think. Given the IP3's of
> >40-45 dB quoted, to you think that it would be worth
> trying >this at 144 MHz?
> >> I made some experiments with the NC7SB3157, another
> member >> of the Fairchild CMOS switch family. I tried to
> use it to >> convert from 70MHz to 10.7MHz but the results
> were not too >> encouraging. I do not remember the details
> any more, but >> performance was similar to what I could
> get with the J310. >> Since the microscopic devices are
> awkward to work with I >> decided to use the J310......
> >> Some day the modern switches will be superiour for use
> at >> VHF. I do not know if the day has already arrived,
> my >> tests did not give good enough IM3 performance but
> I did >> not study very carefully since I do not have the
> tools to >> work with these very small components.
> >> Maybe someone will make a PCB with just the mixer on
> it? >>
> >> 73
> >> Leif / SM5BSZ