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Collins 1.2 KHz Mechanical Filter Type F-455-FD-12, P/N 526-9690-010 Used for Hammarlund HQ-180 / A Filter Modification NOS

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MPN:
526-9690-010
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$8.00 (Fixed Shipping Cost)
  • NOS Collins F-455-FD-12 Mechanical Filter P/N 526-9690-010. 455 kHz IF, 1.2 kHz bandwidth narrow filter with sharp skirts for CW or data modes. Excellent Collins quality, 350 pF resonating cap, steep shape factor. Ideal for S-Line receivers, KWM transceivers, or other 455 kHz IF radios. Rare New Old Stock—perfect restoration or upgrade part. Fast shipping from [Your Location]. Great for serious ham operators and collectors! Used for Hammarlund HQ-180 and HQ-180A Filter Modification
  • NOS Collins F-455-FD-12 Mechanical Filter P/N 526-9690-010. 455 kHz IF, 1.2 kHz bandwidth narrow filter with sharp skirts for CW or data modes. Excellent Collins quality, 350 pF resonating cap, steep shape factor. Ideal for S-Line receivers, KWM transceivers, or other 455 kHz IF radios. Rare New Old Stock—perfect restoration or upgrade part. Fast shipping from [Your Location]. Great for serious ham operators and collectors! Used for Hammarlund HQ-180 and HQ-180A Filter Modification
  • NOS Collins F-455-FD-12 Mechanical Filter P/N 526-9690-010. 455 kHz IF, 1.2 kHz bandwidth narrow filter with sharp skirts for CW or data modes. Excellent Collins quality, 350 pF resonating cap, steep shape factor. Ideal for S-Line receivers, KWM transceivers, or other 455 kHz IF radios. Rare New Old Stock—perfect restoration or upgrade part. Fast shipping from [Your Location]. Great for serious ham operators and collectors! Used for Hammarlund HQ-180 and HQ-180A Filter Modification
  • NOS Collins F-455-FD-12 Mechanical Filter P/N 526-9690-010. 455 kHz IF, 1.2 kHz bandwidth narrow filter with sharp skirts for CW or data modes. Excellent Collins quality, 350 pF resonating cap, steep shape factor. Ideal for S-Line receivers, KWM transceivers, or other 455 kHz IF radios. Rare New Old Stock—perfect restoration or upgrade part. Fast shipping from [Your Location]. Great for serious ham operators and collectors! Used for Hammarlund HQ-180 and HQ-180A Filter Modification
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Description

Collins 1.2 KHz Mechanical Filter Type F-455-FD-12, P/N 526-9690-010 Used for Hammarlund HQ-180 / A Filter Modification NOS

the Collins F-455-FD-12 (P/N 526-9690-010) is used for modifying the Hammarlund HQ-180 (and HQ-180A). DetailsA well-known modification article by Dallas Lankford (published around 1990 in DX News / IRCA) describes installing Collins F455FD-series mechanical filters (including the exact FD-12 variant) into the HQ-180(A).
  • The mod typically installs the filter right after the first mixer in the 455 kHz IF chain for significantly improved selectivity.
  • The FD-12 (1.2 kHz bandwidth) is a narrow CW-oriented filter — excellent for sharp CW or very tight SSB/data work, but narrower than typical AM/SSB filters.
  • The article includes a table listing the FD-12 with part number 526-9690-010, resonating capacitor 350 pF, and its bandwidth specs (matching what I provided earlier).
     
     
Many HQ-180 owners perform this kind of Collins mechanical filter upgrade because the stock crystal filter and LC circuits in the HQ-180 are good but can be outperformed by a high-quality mechanical filter for adjacent channel rejection.
 
 
Compatible Radios and UsesThis is a 455 kHz IF mechanical bandpass filter in the FD series (plug-in style, often with external resonating capacitor). It was used in various Collins equipment and is suitable for high-performance HF receivers or transceivers requiring a narrow ~1.2 kHz filter for CW or narrow SSB/data modes.
 
 
It appears in contexts with other Collins 455 kHz filters (similar to those in S-Line or military gear) and has been adapted for homebrew projects or other vintage radios with 455 kHz IF strips. The FD series (like the previously queried FD-19) is noted for use in select Collins and compatible receivers needing sharp selectivity.
 
 
Specifications
  • Center Frequency: 455 kHz nominal.
     
     
  • Bandwidth: 1.2 kHz nominal (typically at ~4–6 dB points); max ~8.07 kHz at 60 dB. Excellent shape factor with steep skirts.
     
  • Resonating Capacitor: 350 pF (external).
     
    worldradiohistory.com
  • Type: Mechanical bandpass (multi-resonator torsional design), FD case/pin style.
  • Other: Low insertion loss, high stability, superior selectivity compared to ceramic filters of the era. Designed for communications equipment with tight IF filtering.
     
     
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