Loss in Variable Crystal filter

[Charlie Kahwagi]

Hello all,
            I have returned to using my K2 seriously, and I am curious if anyone else finds the following on their K2:

When I switch from filter OP 1 on SSB  to a narrower filter (i.e  through the variable B/W filter on the main board)  I get approx 10 dB loss of signal strength.

Does this sound right?    The S meter reads less,  the AF out with AGC off is less and  I am curious if the 5 pole variable bw crystal filter, should be that  much lossier then the fixed 7 pole filter on the SSB board.

I know there maybe MANY reasons,  poor crystals, impedance matching issues ( I do have the NB installed) etc.....but has anyone else seen this much variation and is there something in particular that I should look at to improve it?

I cannot say that the S+N/N ratio is degraded,  but it is annoying that it is such a difference.   I feel I am losing out on gain, when I am listening in very low B/Ws in CW.

73
VK3NX
Charlie
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Jack Smith-6]

Unlike fine wine, carbon composition resistors do not get better with age.

I ran across a couple hundred brand new carbon composition resistors
manufactured around 1960 while looking for something else today and
spent a couple hours measuring them to see how badly they had drifted. I
found the results interesting enough to add a page on the measurements
at http://www.cliftonlaboratories.com/carbon_composition_resistors.htm.

There may be reasons to keep 50 year old carbon composition resistors
around, such as restoring period radios, but these parts do age poorly,
even when "new old stock." Before using one, I would carefully check the
value as odds are good it will not be in tolerance.

Jack K8ZOA
www.cliftonlaboratories.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[N2EY]

In a message dated 7/15/07 6:03:54 PM Eastern Daylight Time,
[hidden email] writes:


> There may be reasons to keep 50 year old carbon composition resistors
> around, such as restoring period radios, but these parts do age poorly,
> even when "new old stock."

Considering the technology, an upwards drift of about 10% over a half-century
doesn't seem too bad, really.

btw, I think those are half-watters.

Before using one, I would carefully check the
>
> value as odds are good it will not be in tolerance.
>

I always do!

One thing I have always found amazing is how at least some old parts,
of the cheapest possible construction, will test like brand new after
so many decades.

73 de Jim, N2EY


**************************************
 Get a sneak peak of the
all-new AOL at http://discover.aol.com/memed/aolcom30tour
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Brett gazdzinski-2]

 
I don't think I have any resistors newer then
30 years old, and I have millions of resistors!

I check them, but don't find many far off, you have to keep
them dry I think.

Brett
N2DTS

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Geoffrey Mackenzie-Kennedy-2]

Ron D'Eau Claire wrote on Monday, July 16, 2007 2:49 AM:

> Back then we paid a huge penalty if we wanted a resistor within 5% or
> (gasp!) 1% of the stated value. They were used only in a very few critical
> places. Nowadays we routinely expect 1% tolerance from ordinary
> off-the-shelf cheap resistors.

 ----------------------------------------------------------------------

You were lucky to be able to get resistors within 10% of the required value
 :-) In 1946 my only sources were defunct domestic receivers, difficult to
find in VQ8, and many "liberated" resistors had to be trimmned  to the
required value by filing a notch (or several) in the resistor's body. A dab
of nailpolish "borrowed" from my sister completed the job.

73,
Geoff
GM4ESD


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[John Magliacane]

--- Jack Smith <[hidden email]> wrote:

> Unlike fine wine, carbon composition resistors do not get better with age.

Yea verily!

I have observed effect myself with quite a number of 1/4-watt 5% tolerance
resistors that have never been used, are probably at least 20 years old, and
have been stored at room temperature.

In particular, a collection of 75 ohm resistors read extremely high -- in some
cases nearly DOUBLE their rated value!

I have not seen this effect as much with carbon film resistors of similar
value, vintage, tolerance, and power rating.

I made this discovery almost by mistake about two years ago.  I had been using
the 75-ohm resistors as terminators in NTSC analog video circuits for quite a
number of years.  While these circuits worked fine when tested on the bench
using a video test pattern generator (that had been previously calibrated using
one of these problem resistors as a terminator), improper video levels were
experienced when these circuits were used outside the test environment.


73, de John, KD2BD


Visit John on the Web at:

        http://kd2bd.ham.org/
.
.
.
.


       
____________________________________________________________________________________
Looking for a deal? Find great prices on flights and hotels with Yahoo! FareChase.
http://farechase.yahoo.com/
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com