I'm interested in getting several of these filters (for the 75A4):

500 Hz, anything between up to but not including 3.1 kHz.

Need sources, prices.

Make reply post or send private email to the source of this post
)

Thanks.

Art Sowers wrote:

I'm interested in getting several of these filters (for the 75A4):

500 Hz, anything between up to but not including 3.1 kHz.

Need sources, prices.

Rockwell-Collins still makes the size J filters. From the 2005 catalogue:


NSN Type Bandwidth
526-9089-000 F455J-31 2.8
526-9091-000 F455J-60 5.5
526-9154-000 F455J-05 0.38
526-9155-000 F455J-15 1.2
526-9156-000 F455J-21 2

You can also make adaptors out of perfboard to fit the PC board mount
filters onto a socket, if you find them at a hamfest.

Otherwise try .
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Tue, 31 May 2011, Scott Dorsey wrote:

Art Sowers wrote:

I'm interested in getting several of these filters (for the 75A4):

500 Hz, anything between up to but not including 3.1 kHz.

Need sources, prices.

Rockwell-Collins still makes the size J filters. From the 2005 catalogue:

How interesting!!!


NSN Type Bandwidth
526-9089-000 F455J-31 2.8
526-9091-000 F455J-60 5.5
526-9154-000 F455J-05 0.38
526-9155-000 F455J-15 1.2
526-9156-000 F455J-21 2

You can also make adaptors out of perfboard to fit the PC board mount
filters onto a socket, if you find them at a hamfest.

Otherwise try .

Thanks a lot!!!!

Art

--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Edmund H. Ramm wrote:
In (Scott Dorsey) writes:

Rockwell-Collins still makes the size J filters. From the 2005 catalogue:
[...]

Dave Curry Longwave Product's mechanical filters (exact replacements
for Collins ones) reportedly have less insertion loss and better skirts.
See Electric Radio magazine for more info.

Does 'better' mean tighter or less ringing?

There are sure times when I wish I had a less nasty-sounding filter for
AM on the R-390.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Tue, 31 May 2011, Scott Dorsey wrote:

Edmund H. Ramm wrote:
In (Scott Dorsey) writes:

Rockwell-Collins still makes the size J filters. From the 2005 catalogue:
[...]

Dave Curry Longwave Product's mechanical filters (exact replacements
for Collins ones) reportedly have less insertion loss and better skirts.
See Electric Radio magazine for more info.

Does 'better' mean tighter or less ringing?

There are sure times when I wish I had a less nasty-sounding filter for
AM on the R-390.
--scott

I'll have to put on my "to do" list that I need to search the web for
sources of these filters (as well as ER magazine). And, see if Collins has
a website of their own (I should have done that, too, but I have variable
lazyness...and I'm not in a big hurry on this project).

I did send to that Collins email address a request for further information
and have not, as yet, received an answer (I notice email responses to
email queries can be all over the spectrum from minutes later to days
later to no answer at all).

For a nice-sounding CW filter, I have used an audio frequency equalizer
(picked up mine from a thrift store for $5, its a Realistic [Radio Shack]
jobber). I max boost 500 Hz sliding pot on both channels, and max depress
the pots on all other frequencies, and feed speaker output into input of
one channel, output of that channel into input of the other channel, and
run output of other channel into input of an amplifier driving either a
speaker or earphones. Bandwidth "sounds" (not measured) like maybe about
300-400 Hz. The next frequencies above and below 500 Hz are 250 Hz and
1 kHz. I might get narrower if I boost at 250, etc, but tone is too low
for my ears. I thought I wasn't getting any detectable ringing at all
on this setup. The calibrations are max/min 12 db, so that should put
unwanted frequencies down 24+ db per channel, or 48 db for both, no?

Scott, for AM on the R-390: are you sure its the filter? Not distortion in
the audio string? Have you tried any other post detection path (eg. a
separate receiver, even an old AM radio where you feet the 455 kc output
from the R-390 to the input of the IF on the AM radio and see what audio
quality you can get? I'm not familiar with the R390 (does it have
mechanical filters?).



--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Art Sowers wrote:
For a nice-sounding CW filter, I have used an audio frequency equalizer
(picked up mine from a thrift store for $5, its a Realistic [Radio Shack]
jobber). I max boost 500 Hz sliding pot on both channels, and max depress
the pots on all other frequencies, and feed speaker output into input of
one channel, output of that channel into input of the other channel, and
run output of other channel into input of an amplifier driving either a
speaker or earphones. Bandwidth "sounds" (not measured) like maybe about
300-400 Hz. The next frequencies above and below 500 Hz are 250 Hz and
1 kHz. I might get narrower if I boost at 250, etc, but tone is too low
for my ears. I thought I wasn't getting any detectable ringing at all
on this setup. The calibrations are max/min 12 db, so that should put
unwanted frequencies down 24+ db per channel, or 48 db for both, no?

You might try setting the filters on the two ears a little bit different,
so that higher tones are to the right and lower tones are to the left. I
find this helps pick out signals from a pileup.

The filters on those cheap EQs are probably fairly wide; you can measure the
Q with a meter and a signal generator if you want to really know.

Scott, for AM on the R-390: are you sure its the filter? Not distortion in
the audio string? Have you tried any other post detection path (eg. a
separate receiver, even an old AM radio where you feet the 455 kc output
from the R-390 to the input of the IF on the AM radio and see what audio
quality you can get? I'm not familiar with the R390 (does it have
mechanical filters?).

There is lots of distortion in the audio string, although the line output
is definitely much cleaner than the speaker level output. However, there is
just outrageous amounts of ringing on the 8KC filter. If I go to the 16 KC
filter it's much cleaner but of course there's a wider bandwidth too.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On May 31, 7:12*am, Art Sowers wrote:
I'm interested in getting several of these filters (for the 75A4):

500 Hz, anything between up to but not including 3.1 kHz.

Need sources, prices.

Make reply post or send private email to the source of this post
)

Thanks.

FWIW, I have an F 455 J 31 in front of me that I'd be happy to part
with for any reasonable payment. As far as I know, it's in good
condition, removed from (if I'm not mistaken) a Collins 490T HF
avionics transceiver. I'd be happy to check it on an HP8753ES network
analyzer to insure it's OK, if I find info on pin connections and in/
out matching to the analyzer's 50+j0 ohms. I gather this is the one
you _don't_ need, but perhaps someone else does. (Looks like probably
pins 1&2, and 6&7, are the in/out...9 pin miniature tube base.)

Cheers,
Tom