F3WT <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Bonjour/bonsoir Rien,
Hello all,
Thank you very much indeed
Insertion loss I forgot to ask is very well depicted in your plots !
(2 to 3 dB, did i read correctly though?)
Taking only one half reduces BW. Adding/cascading a third increases
BW as you noticed, probably loos as well but reduces slope factor.
I think as well that adding a diplexer behind first mixer should
increase IM/IP3 performance. Does anybody have thoughts or
experience with this as well?
73's
Pierre - F3WT
Le 5 janv. 06 à 02:50, R.van Trotsenburg a écrit :
Direct copy
-------------Forwarded Message-----------------
From: R.van Trotsenburg, 100415,1216
To: INTERNET:[email protected],
INTERNET:[email protected]
Date: 5/1/2006 2:45 PM
RE: [drakelist] Roofing filter R7 TR7
Hallo Pierre,
A year ago I have done some measurements with roofing filters in
the 3x TR7
and 1x R7.
I have measured the filter passbands response on a HP8407 based
network
analyzer.
The impedance I have measured with is 50ohms.
The shape in the original TR7s and R7 was far from optimum
I did improve this by resoldering the filter shielding and
readjusting the
filter.
The results:
9kHz@ 3dB
11kHz@ 6dB
35kHz@ 60dB
All filters showed more or less some an off centering of about 1 to
2 kHz.
This causes some asymmetry between the response of the USB and LSB.
In a
very early TR7 this was more as 5kHz. Here the filter crystals had
to be
replaced.
The filters stop band measured in circuit in the TR7 are not as
good as on
the analyzer. This is probably caused by the not ideal termination
in the
2nd IF board. And some filter leak or filter blow by.
I also recently did some tests with 3 instead of 2 crystals in the
filter.
This gives a much better slopes, but did widen the actual top
passband.
Here the termination became even more critical. I will do more
tests if
time allows me.
I have included four files to this email with the measured curves.
The response on the analyzer (Hor 10kHz/div Vert 10dB/div).
118_1833c.jpg
Tested inside the TR7 (parameters in the picure) 118_1835.jpg and
118_1837.jpg
My network analyzer setup FLTR-TST.pdf
Warning:
Be very careful with testing and adjusting the roofing filter. If
you do
not have the proper test equipment you will end up in very deep
trouble !
Also see the internet site by PA0CMU
http://home.wanadoo.nl/cmulder/drake.htm, where we publish our Drake
experiences.
73's Rien PA0TRT
Mail to [EMAIL PROTECTED]
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Message text written by INTERNET:[email protected]
F3WT <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Hi all:
A question for a 25WPM reply!..Hi!
Does you or anybody know what the in/out impedance of that 48,05MHz
roofing filter is?
The slope factor of both halves? of each? and bandpass of each?
( total is 8kHz, right?)
Mni tnx
--... ...--
Pierre- F3WT
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<
<118_1833c.jpg>
<118_1835c.jpg>
<118_1837c.jpg>
<FLTR-TST.pdf>
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