20 MURATA CFUM 455 I CERAMIC FILTERS
 

check out these filters

http://cgi.ebay.com/ws/eBayISAPI.dll...m=5766301 086

Too bad you don't give the specifcations, you might get a lot more
interest.

Terry

Well,now I know what filters look like,as pertains to radios
anyway.(staying on topic here,just like I always do) Nederlands,eh? I
know of a guy in Nederlands (I get his email newsletters,I can prove
that too) who sells genuine World War Two Jeep parts.
cuhulin

TERRY,

If these Murata 455 Ceramic Filters interest you, then you may
wish to take a look at this replacement for a 455 kHz IF Filter.

"Channel Guard" RX 455 kHz IF Filter.
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5762938320

* The 455 KHz version is an ultra narrow, 3-pole ceramic filter that
replaces the existing (and broader) 1-pole Murata ceramic filter. (It's
that small black or gray plastic cube soldered into the main CB
chassis.) Just unsolder the old filter, install the 3 CHANNEL GUARD
bare wires into the corresponding empty INPUT/OUTPUT/GROUND holes, and
connect to +8-13 VDC. You are done!

Channel Guard Filter Hook-Up Details
http://www.cbcintl.com/docs/cghookup.htm
http://www.cbcintl.com/docs/CG455-HOOKUP.pdf

= = = wrote:

Too bad you don't give the specifcations,
you might get a lot more interest.

Terry

For One and All,

I own a small shirtpocket size Westinghouse AM/FM/Shortwave Radio.About
six years ago,I was listening to it and I laid it down on my couch and I
went to my kitchen.When I got up,it slid off my couch and hit the
hardwood floor.I think it landed on the on/off/volume control knob when
it hit the floor.I removed the chassis from the cabinet and I looked at
it.It looks to me like from the shaft (the knob fits on) on back like a
sort of a little cube shaped affair and quite a few solder connections
where the "cube" was soldered to the radio's circuit board.I know how to
solder but such close quarters as that situation is,I don't think I can
solder it back together properly.I wouldn't mind snail mailing the radio
via UPS to somebody to see if it is worthwhile trying to repair the
radio.Of course,when it hit the floor,it might have damaged something
else too and it might not be worth fooling with.I would be glad to pay
what it's worth to have the radio repaired and shipping and handling
charges both ways.I think it is a nice little radio.Or it used to be
untill it got broken anyway.I know it's around here somewhere if I can
ever find it again.My old house is incredibly full of junk,it's like
some of those horror movies y'all see on tv.The radio is in a bag
because I didn't put the chassis back in the cabinet.
cuhulin

Thanks, these look like something I could really use!

Terry

I thought those were CFU-455I................that would be a 4kHz bandwidth
with a 455kHz center frequency. The Z in / out
would be 2k.

Pete

wrote in message
oups.com...
Too bad you don't give the specifcations, you might get a lot more
interest.

Terry

Pete wrote:
Pete KE9OA Apr 14, 12:57 pm show options

The Inrad unit would be good. About those Murata filters..........the
older
Murata databook I have specifies those filters as having a 2k
impedance.
That is the design spec I have been using for the last several years,
and
the do work ok with that impedance. The 4k spec seems more in line with
the
natural impedance of many of the commercially available crystal
filters.

Pete
----------------------------------------
By 4K I meant BW, I have been using 2K (OK 2010 Ohm metal film,
"low noise" Dale mil surplus) for my load.
I use a BFO from teh ARRL circuit desing handbook circa 1975.
It uses a back to back varicap-diode and a DC voltage for tuning.
I use a MOSFET buffer to couple the out put to our HP SA at work.
My BFO tunes from 450~460KHz and is very clean. I have a HP DFC
and Tektronix scope to verify the Fc. Crude but very stable.

The BFO is routed through a emiter follower to give me 50 Ohms and I
add a 2K resistor in series.

The BFO was from my R392/URR days. That reciever is the little brother
to the R390. It has a 455KHZ IF out and I built my own product detector
using a motorola balanced modulator. The BFO is all that remains of
that
project. It is in a metal Sucretes cough drop box and it was too good
to
toss.

Today I use Altoid metal tins for a lot of my projects. The tiny ones
make
good Reverse & Overvoltage Protection cases because they are RF tight,
the larger ones make either good project boxes, or are great for
holding
sub-modules. It is so much easier to build a "complex" project if the
sections can be built and tested individualyu. Plus it makes "major"
changes a piece of cake. Build a new whatever module.

I am debating building something like the non longer available Kiwa
MAP outboard IF strip complete with a good selection of different BW
filtters, a stand alone BFO, a synch AM detector would be nice, but
I really don't know enough to try to design one from the ground up,
and my search efforts have been a mixed bag.

A seperate IF strip /detector audio conditioning would be very do-able
and this fitler research may well turn into that. I liked Craig's
discription of his "tone tilt" tone control, and found a good circuit
on a electiic guitar site. They had their's set for 1K, but it was
simple
to scale the parts to give his 700Hz tilt point, I like it much better
then the simple hi-cut, or complex trebble/bass boast HiFi tone
controls.

I have a couple of mil-surplus 300-2500HZ AF filtes that are very
narrow
with no ringing. For my needs a outboard detector/etc is looking like a
winner. I really only need one "perfect" IF/BFO/Fitler so I could
switch between my 2 R2000s and use the standard on board/in radio
detector/BFO for back ground monitoring.

I am mainly into utility comms and I almost never have to really dig on
two
freqs at the same time.

As to the source and load resitances when using Murata ceramic filters,
I have found higher Z sources and lower Z loads improve the skirt. But
very
much off on either the in or out really ups the loss.

Terry

Couldn't radios be designed with a "check engine light"? Sort of like on
cars.Just push a few buttons and a digital read out would let you know
what is wrong with the radios,whichever part or parts or whatever.
cuhulin

I looked up the specs, they are aweful filters

the 40db bandwidth is around 15kHz,,,ouch !!!

wide enough for the kitchen sink !

the LF-D6 filters I use have a 60db bandwidth of 12kHz.




"your name here" wrote in message
...
check out these filters

http://cgi.ebay.com/ws/eBayISAPI.dll...m=5766301 086

Hi Terry,
I understand what you mean now! If you need a Sync detector,
I designed one using an Analog Devices AD607 Quadrature I.F. system. A few
years back, I also designed a general purpose product detector for
boatanchor receivers.
With the 600uH I.F. transformer as the L and a varicap diode to tune it,
stability is good. The transformer itself has a tuning range of about 380kHz
to 650kHz, so it will cover the standard 450 through 500kHz IFs.
I like the idea of using separate modules when building
receivers..................that is the approach I use when working on a
brand new design. If you have a good signal generator, you can use that for
LO injection; this way, you can test the RF deck before you get the LO /
synthesizer designed.
It sounds like you have the right equipment to get it done right.

Pete

wrote in message
ups.com...
Pete wrote:
Pete KE9OA Apr 14, 12:57 pm show options

The Inrad unit would be good. About those Murata filters..........the
older
Murata databook I have specifies those filters as having a 2k
impedance.
That is the design spec I have been using for the last several years,
and
the do work ok with that impedance. The 4k spec seems more in line with
the
natural impedance of many of the commercially available crystal
filters.

Pete
----------------------------------------
By 4K I meant BW, I have been using 2K (OK 2010 Ohm metal film,
"low noise" Dale mil surplus) for my load.
I use a BFO from teh ARRL circuit desing handbook circa 1975.
It uses a back to back varicap-diode and a DC voltage for tuning.
I use a MOSFET buffer to couple the out put to our HP SA at work.
My BFO tunes from 450~460KHz and is very clean. I have a HP DFC
and Tektronix scope to verify the Fc. Crude but very stable.

The BFO is routed through a emiter follower to give me 50 Ohms and I
add a 2K resistor in series.

The BFO was from my R392/URR days. That reciever is the little brother
to the R390. It has a 455KHZ IF out and I built my own product detector
using a motorola balanced modulator. The BFO is all that remains of
that
project. It is in a metal Sucretes cough drop box and it was too good
to
toss.

Today I use Altoid metal tins for a lot of my projects. The tiny ones
make
good Reverse & Overvoltage Protection cases because they are RF tight,
the larger ones make either good project boxes, or are great for
holding
sub-modules. It is so much easier to build a "complex" project if the
sections can be built and tested individualyu. Plus it makes "major"
changes a piece of cake. Build a new whatever module.

I am debating building something like the non longer available Kiwa
MAP outboard IF strip complete with a good selection of different BW
filtters, a stand alone BFO, a synch AM detector would be nice, but
I really don't know enough to try to design one from the ground up,
and my search efforts have been a mixed bag.

A seperate IF strip /detector audio conditioning would be very do-able
and this fitler research may well turn into that. I liked Craig's
discription of his "tone tilt" tone control, and found a good circuit
on a electiic guitar site. They had their's set for 1K, but it was
simple
to scale the parts to give his 700Hz tilt point, I like it much better
then the simple hi-cut, or complex trebble/bass boast HiFi tone
controls.

I have a couple of mil-surplus 300-2500HZ AF filtes that are very
narrow
with no ringing. For my needs a outboard detector/etc is looking like a
winner. I really only need one "perfect" IF/BFO/Fitler so I could
switch between my 2 R2000s and use the standard on board/in radio
detector/BFO for back ground monitoring.

I am mainly into utility comms and I almost never have to really dig on
two
freqs at the same time.

As to the source and load resitances when using Murata ceramic filters,
I have found higher Z sources and lower Z loads improve the skirt. But
very
much off on either the in or out really ups the loss.

Terry

Wouldn't that be good! Actually, a couple of radios that have that built in
test equipment (BITE) function are the HF-2050, RA6790/GM, and probably a
host of others.
I like that "check engine light" idea...........just take it to the local
diagnostics shop and have them fix it.

Pete

wrote in message
...
Couldn't radios be designed with a "check engine light"? Sort of like on
cars.Just push a few buttons and a digital read out would let you know
what is wrong with the radios,whichever part or parts or whatever.
cuhulin

Don't forget the Murata CFR series! Too bad Murata stopped making them.
Now, about those LF-D6 filters....................I'll take 500,000 of them.
Just kidding!
How is that new MD receiver working out? DR333 or something like that?

Pete

"mike maghakian" wrote in message
...
I looked up the specs, they are aweful filters

the 40db bandwidth is around 15kHz,,,ouch !!!

wide enough for the kitchen sink !

the LF-D6 filters I use have a 60db bandwidth of 12kHz.




"your name here" wrote in message
...
check out these filters

http://cgi.ebay.com/ws/eBayISAPI.dll...m=5766301 086