increase your receivers selectivity
 

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

I hate to say this Mike, but a filter that is 8.27 kHz wide at 6db is
pretty wide. Good for strong stations with little or no adjacent channel
QRM.

This would actually be a decrease in selectivity, unless of course one
were going from a filter that was say 14 kHz wide at 6db. That is to
say, if one had a 6 kHz (at 6db) filter already installed and went to a
8 kHz (at 6db), that would be a decrease in selectivity.

Steve
Holland, MI

Drake R7, R8 and R8B

Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

on the surface what you say is true, but a bit of digging finds you
wrong for the majority of receivers out there. I must repeat I am
positioning this as an elcellent SWL filter, NOT as a 4/8 DX filter.

I propose the following receivers have worse selectivity than my
filter. you must look at the 60db point as well, a 6/20 filter is a
LOT worse than a 8/12 filter in my book, I am referring to the wide
filter, not the narrow filter with is usually USELESS for SWL work and
can only be used for DX/IDing a station.

R-600
R-1000
R-2000
R-5000 with stock AM filter
FRG-7
FRG-7700
FRG-8800
DX-300
DX-302
DX-394
bearcat DX-1000
R-71
RF-2600
RF-2800
RF-2900
RF-4800
RF-4900


I could go on but when a filter is spec's at 6/15, what that means is
that the 6Khz position is AT BEST 6KHz and is usually 8 KHz!!!!!!! and
usually receivers below $1000 have 6/20 filters that are trash. there
are exceptions but for the most part the industry has everyone fooled,
they had me fooled until I did filter research this year.
my filter is NOT a DX filter it is a great SWL filter, but most
receivers have a sucky DX and SWL filter selection. 2.4/9 is a sucky
DX filter, most receivers come close but seriously drop the ball.


also as a point of reference, the famous Kiwa filter is an LF-4H, it
is a 4Khz filter that he wisely sells as a 6 KHz filter because he
hasn't been tricked by the industry as everyone else has.


the ultimate soluton is to replace both filters in a receiver , the
wide being my filter and the narrow being a nice 4/10 filter, NOT a
4/15 filter.



N8KDV wrote in message ...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

also the fact that you use excellent drake receivers means you know
that these receivers I mention use cheap filters and that shape
factors are important. If drake used filters like the receivers I
mentioned they would not be the classics they are today.

N8KDV wrote in message ...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

Mike Maghakian wrote:

on the surface what you say is true, but a bit of digging finds you
wrong for the majority of receivers out there. I must repeat I am
positioning this as an elcellent SWL filter, NOT as a 4/8 DX filter.

I propose the following receivers have worse selectivity than my
filter. you must look at the 60db point as well, a 6/20 filter is a
LOT worse than a 8/12 filter in my book, I am referring to the wide
filter, not the narrow filter with is usually USELESS for SWL work and
can only be used for DX/IDing a station.

R-600
R-1000
R-2000
R-5000 with stock AM filter
FRG-7
FRG-7700
FRG-8800
DX-300
DX-302
DX-394
bearcat DX-1000
R-71
RF-2600
RF-2800
RF-2900
RF-4800
RF-4900

I could go on but when a filter is spec's at 6/15, what that means is
that the 6Khz position is AT BEST 6KHz and is usually 8 KHz!!!!!!! and
usually receivers below $1000 have 6/20 filters that are trash. there
are exceptions but for the most part the industry has everyone fooled,
they had me fooled until I did filter research this year.
my filter is NOT a DX filter it is a great SWL filter, but most
receivers have a sucky DX and SWL filter selection. 2.4/9 is a sucky
DX filter, most receivers come close but seriously drop the ball.

also as a point of reference, the famous Kiwa filter is an LF-4H, it
is a 4Khz filter that he wisely sells as a 6 KHz filter because he
hasn't been tricked by the industry as everyone else has.

How has anyone been 'tricked'? I've looked at the LFH-4S, (I'm guessing this is the one you are
referring to), it is hardly a 4 kHz filter. Look at the plot:

http://www.kiwa.com/sony.html



the ultimate soluton is to replace both filters in a receiver , the
wide being my filter and the narrow being a nice 4/10 filter, NOT a
4/15 filter.

N8KDV wrote in message ...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

Great topic between you and Steve, I like this thread, I'm saving it for
future reference.

Great to read a shortwave post in here again. :-) Good job guys!

--
~*~*~Monitoring the Spectrum~*~*~
***GO BEARCATS***
~*~*~Oct.15th Payback Begins~*~*~*~
~~~Hammarlund129X/140X~~~
**Heathkit Q Multiplier**
GE P-780
"Mike Maghakian" wrote in message
om...
on the surface what you say is true, but a bit of digging finds you
wrong for the majority of receivers out there. I must repeat I am
positioning this as an elcellent SWL filter, NOT as a 4/8 DX filter.

I propose the following receivers have worse selectivity than my
filter. you must look at the 60db point as well, a 6/20 filter is a
LOT worse than a 8/12 filter in my book, I am referring to the wide
filter, not the narrow filter with is usually USELESS for SWL work and
can only be used for DX/IDing a station.

R-600
R-1000
R-2000
R-5000 with stock AM filter
FRG-7
FRG-7700
FRG-8800
DX-300
DX-302
DX-394
bearcat DX-1000
R-71
RF-2600
RF-2800
RF-2900
RF-4800
RF-4900


I could go on but when a filter is spec's at 6/15, what that means is
that the 6Khz position is AT BEST 6KHz and is usually 8 KHz!!!!!!! and
usually receivers below $1000 have 6/20 filters that are trash. there
are exceptions but for the most part the industry has everyone fooled,
they had me fooled until I did filter research this year.
my filter is NOT a DX filter it is a great SWL filter, but most
receivers have a sucky DX and SWL filter selection. 2.4/9 is a sucky
DX filter, most receivers come close but seriously drop the ball.


also as a point of reference, the famous Kiwa filter is an LF-4H, it
is a 4Khz filter that he wisely sells as a 6 KHz filter because he
hasn't been tricked by the industry as everyone else has.


the ultimate soluton is to replace both filters in a receiver , the
wide being my filter and the narrow being a nice 4/10 filter, NOT a
4/15 filter.



N8KDV wrote in message
...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

Drake doesn't use them in everything up to the R7/R8 series, but they do use
them in the SW1, SW2, and the SW8. Although the ceramic filter route is the
cheaper way to go, vs. LC circuits or crystal/mechanical filters at the
final I.F. some enhanced steepness on the curves can be obtained by using a
good roofing filter at the 1s I.F.
On another note...........if you look at Murata's specs, especially for the
CFU/CFWS series, you will see that the C.F. is specified at (plus or minus
two kHz). Still not a show stopper; that is probably a big reason that the
AOR7030 has that self alignment function, whereby the filters are swept, and
probably, the 2nd LO is warped to provide symmetrical response.

Pete

Mike Maghakian wrote in message
om...
also the fact that you use excellent drake receivers means you know
that these receivers I mention use cheap filters and that shape
factors are important. If drake used filters like the receivers I
mentioned they would not be the classics they are today.

N8KDV wrote in message
...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

One other thing I forgot to mention............you will see the skirt
selectivity of a filter change in the cheaper filters, depending on the
drive level from the RF source. This would be caused from feedaround effects
inside of the filter. Probably, the best way to measure a filter in
question would be to use an HP 8753 Network Analyzer; this is what the
filter manufacturers would probably be using. When I was working for
Motorola, I did get some filter samples from Toko, and what they used was
and HP 3577 Network Analyzer. Alternatively, you could use a fairly good
spectrum analyzer, such as an HP 8590, along with a tracking generator, if
you are not interested in such things as input/output return loss, group
delay, etc.
The whole point of this is that unless you can duplicate the test
measurement setup of the manufacturer, you MIGHT be comparing apples and
oranges. Just a few thoughts.

Pete

Mike Maghakian wrote in message
om...
also the fact that you use excellent drake receivers means you know
that these receivers I mention use cheap filters and that shape
factors are important. If drake used filters like the receivers I
mentioned they would not be the classics they are today.

N8KDV wrote in message
...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

nice to hear from you pete !

this page explains how the graph was produced using a HP 3590A Wave
Analyzer and several other pieces of equipment:

http://members.cts.com/king/j/jlkolb/site/MFtest.htm


"Pete KE9OA" wrote in message ...
One other thing I forgot to mention............you will see the skirt
selectivity of a filter change in the cheaper filters, depending on the
drive level from the RF source. This would be caused from feedaround effects
inside of the filter. Probably, the best way to measure a filter in
question would be to use an HP 8753 Network Analyzer; this is what the
filter manufacturers would probably be using. When I was working for
Motorola, I did get some filter samples from Toko, and what they used was
and HP 3577 Network Analyzer. Alternatively, you could use a fairly good
spectrum analyzer, such as an HP 8590, along with a tracking generator, if
you are not interested in such things as input/output return loss, group
delay, etc.
The whole point of this is that unless you can duplicate the test
measurement setup of the manufacturer, you MIGHT be comparing apples and
oranges. Just a few thoughts.

Pete

Mike Maghakian wrote in message
om...
also the fact that you use excellent drake receivers means you know
that these receivers I mention use cheap filters and that shape
factors are important. If drake used filters like the receivers I
mentioned they would not be the classics they are today.

N8KDV wrote in message
...
Mike Maghakian wrote:

most receivers don't come with adequate selectivity. now for a small
amount and with a bit of skill you can change that. check out the
LF-D6 ceramic filter on my web page.

http://maghakian.home.att.net/

Oh yes. what receiver(s) are you proposing that these filters be put in?

Pete KE9OA wrote:
snipped

On another note...........if you look at Murata's specs, especially for the
CFU/CFWS series, you will see that the C.F. is specified at (plus or minus
two kHz). Still not a show stopper; that is probably a big reason that the
AOR7030 has that self alignment function, whereby the filters are swept, and
probably, the 2nd LO is warped to provide symmetrical response.

Pete

That's an impressive feature for a consumer grade HF receiver
(AOR-7030).


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----

"Brian Denley" ) writes:
Pete:
What is your website URL?
Thanks

It would be:
http://home.att.net/~n.gianakopoulos...ome.html-.html

Michael

They are using a pretty decent roofing filter; if you are thinking about
improving the IP3 of this receiver, a good way to go is to get a crystal
filter with a 500Hz bandwidth at the reference oscillator frequency for the
synthesizer. You probably would need to add an impedance
matching/buffer-gain stage at the output of the crystal filter to regain the
signal loss through the filter. It gets more complicated, because you have
to watch the noise characteristics of the buffer/gain stage. As it is,
Drake does a pretty good job with the receiver. You could go with an
8-element roofing filter; the Racal 6790 uses this type of filter for its
1st I.F. of 45MHz. I had an extra front end for my 6790, except that it had
a blown mixer. I was going to pull off the crystal filter, but I was
feeling extremely lazy that day, so I ended up giving it away. Now, you
could make up your own crystal filter, but without at least a spectrum
analyzer and tracking generator, it would be hard to tune it for flat
bandpass.
An alternative would be to call up Temec; they do sell in small quantities,
so you might be able to pick up a multipole crystal filter, if you really
wanted to change that roofing filter in your receiver.

Pete

starman wrote in message
...
Pete KE9OA wrote:
snipped

If anybody has any filter questions, feel free to e-mail me directly; I
have
been using many different types in my homebrew units over the years, so
I've
picked up a few things when it comes to impedance matching, etc.

Pete

Do you have any suggestions for a better roofing filter for the
Drake-R8x series?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----

I'm not really itching to replace the roofing filter in my R8B. I was
just wondering what the options might be. The IP3 is good enough for
most situations. Were you thinking about reducing phase noise by using
the 500-HZ crystal filter for the synthesizer?

Thanks


Pete KE9OA wrote:

They are using a pretty decent roofing filter; if you are thinking about
improving the IP3 of this receiver, a good way to go is to get a crystal
filter with a 500Hz bandwidth at the reference oscillator frequency for the
synthesizer. You probably would need to add an impedance
matching/buffer-gain stage at the output of the crystal filter to regain the
signal loss through the filter. It gets more complicated, because you have
to watch the noise characteristics of the buffer/gain stage. As it is,
Drake does a pretty good job with the receiver. You could go with an
8-element roofing filter; the Racal 6790 uses this type of filter for its
1st I.F. of 45MHz. I had an extra front end for my 6790, except that it had
a blown mixer. I was going to pull off the crystal filter, but I was
feeling extremely lazy that day, so I ended up giving it away. Now, you
could make up your own crystal filter, but without at least a spectrum
analyzer and tracking generator, it would be hard to tune it for flat
bandpass.
An alternative would be to call up Temec; they do sell in small quantities,
so you might be able to pick up a multipole crystal filter, if you really
wanted to change that roofing filter in your receiver.

Pete

starman wrote in message
...
Pete KE9OA wrote:
snipped

If anybody has any filter questions, feel free to e-mail me directly; I
have
been using many different types in my homebrew units over the years, so
I've
picked up a few things when it comes to impedance matching, etc.

Pete

Do you have any suggestions for a better roofing filter for the
Drake-R8x series?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 80,000 Newsgroups - 16 Different Servers! =-----