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).


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"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?


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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?


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