Reply
 
LinkBack Thread Tools Search this Thread Display Modes
  #1   Report Post  
Old July 14th 06, 07:33 PM posted to rec.radio.amateur.boatanchors
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 113
Default 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
  #2   Report Post  
Old July 15th 06, 09:29 AM posted to rec.radio.amateur.boatanchors
Ed Ed is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 7
Default 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



Reply
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Matching to Crystal Filter David Homebrew 12 June 7th 06 06:51 AM
Crystal Filter Matching David Homebrew 3 January 16th 06 09:39 AM
Kenwood YG-455CN-1 crystal filter, AR7030 & too many daughters [email protected] Shortwave 1 February 12th 05 05:58 AM
Filter Design/Analysis program FREE with powerful crystal ladder designs Neil Homebrew 2 May 17th 04 08:44 AM


All times are GMT +1. The time now is 04:47 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017