455Kc crystal filter
 

Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

455Kc crystal filter
 

On Fri, 14 Jul 2006 05:05:27 GMT, "Ed" wrote:

Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

Your first bit of education would be to offer a link to what it is
you're talking about.

455Kc crystal filter
 

Ed, I think you'll find that its a bandpass filter centered on 455kHz.
The part about a "crystal socket" is a mystery..... You also need
to know what the loss and bandwidth is before considering it. Also,
does your particular application make accommodation for a filter (loss
compensation, et al). If not, you'll need to do some design work,
albeit simple.

Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

455Kc crystal filter
 

K3HVG ) writes:
Ed, I think you'll find that its a bandpass filter centered on 455kHz.
The part about a "crystal socket" is a mystery..... You also need
to know what the loss and bandwidth is before considering it. Also,
does your particular application make accommodation for a filter (loss
compensation, et al). If not, you'll need to do some design work,
albeit simple.

Actually, I don't think it can be defined from the poster's description.
It could merely be a crystal, after all many an old receiver did use a
single crystal in a filter at that IF, and that would explain the "crystal
socket".

Either the Ebay description is suspect, if it can't explain things then
maybe the seller doesn't know what he's got, or it's been garbled when
posted here.

Michael VE2BVW



Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

455Kc crystal filter
 

I also recall a test set in the early days that had a crystal
oscillator that generated a test signal at IF frequencies ,like 455,
10.7 etc using plugin xtals..W4PQW
Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

455Kc crystal filter
 

I also recall a test set in the early days that had a crystal
oscillator that generated a test signal at IF frequencies ,like 455,
10.7 etc using plugin xtals..W4PQW
Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?

455Kc crystal filter
 

On 7/14/06 9:08 AM, in article , "Michael Black"
wrote:

K3HVG ) writes:
Ed, I think you'll find that its a bandpass filter centered on 455kHz.
The part about a "crystal socket" is a mystery..... You also need
to know what the loss and bandwidth is before considering it. Also,
does your particular application make accommodation for a filter (loss
compensation, et al). If not, you'll need to do some design work,
albeit simple.

Actually, I don't think it can be defined from the poster's description.
It could merely be a crystal, after all many an old receiver did use a
single crystal in a filter at that IF, and that would explain the "crystal
socket".

Either the Ebay description is suspect, if it can't explain things then
maybe the seller doesn't know what he's got, or it's been garbled when
posted here.

Michael VE2BVW



Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?






I looked it up..... It is clearly just a crystal at 455 kHz. There are
three available. It could be used in a notch filter, a bfo, or to make a
simple 455kHz oscillator for boatanchor alignment.

Don

455Kc crystal filter
 

Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?


There's an interesting-looking Hallicrafters 455kc crystal filter
on eBay, I assume that's what Ed is referring to.
The crystal holder has a neat lead seal with a Hallicrafters "h"
impressed on it, to keep anyone from opening the holder.

That type of filter is a prewar design (one-crystal filter),
where the crystal was part of a balanced circuit
before the first I.F. amplifier. It could be used
with a variable "phasing" capacitor
to null a heterodyne, or sharpen reception bandwidth.
Most receivers used a switch-selected set of resistors
across the single crystal filter
to reduce the selectivity to permit 'phone reception.
(for example: the Collins 75A-2 receiver)

Better than nothing on a crowded c.w. band, but the ringing
is annoying and tiring. Modern crystal filters
are the lattice circuit type, where an array of crystals are used
to get a flat-topped passband of the desired bandwidth.
A "six pole crystal filter" has six individual crystals in the filter.

73,
Ed Knobloch

455Kc crystal filter
 

Exactly what I wanted to know, thanks Ed.
"Edward Knobloch" wrote in message
news:yrRtg.12$pR4.8@trndny01...
Ed wrote:
Please educate me. I see one of these for sale on ebay that plugs into a
crystal socket. I know that a lot of boatanchor IF's are 455Kc, does this
generate the IF for old receivers, or is it a bandpass filter?


There's an interesting-looking Hallicrafters 455kc crystal filter
on eBay, I assume that's what Ed is referring to.
The crystal holder has a neat lead seal with a Hallicrafters "h"
impressed on it, to keep anyone from opening the holder.

That type of filter is a prewar design (one-crystal filter),
where the crystal was part of a balanced circuit
before the first I.F. amplifier. It could be used
with a variable "phasing" capacitor
to null a heterodyne, or sharpen reception bandwidth.
Most receivers used a switch-selected set of resistors
across the single crystal filter
to reduce the selectivity to permit 'phone reception.
(for example: the Collins 75A-2 receiver)

Better than nothing on a crowded c.w. band, but the ringing
is annoying and tiring. Modern crystal filters
are the lattice circuit type, where an array of crystals are used
to get a flat-topped passband of the desired bandwidth.
A "six pole crystal filter" has six individual crystals in the filter.

73,
Ed Knobloch