ad.1. Heathkit Filter Measurements
This section contains a series of measurements made on one example of each type of
Heathkit SB-line crystal filters at 3.395MHz.
AM (wide) 404-314 SSB 404-200 CW 404-284-1
Attenuation
dB
Low Side High Side Low Side High Side Low Side High Side
-1 3.39418 3.39489 3.39407 3.39602 3.39525 3.39545
-3 3.394 3.39889 3.39397 3.39610 3.39522 3.3955
-10 3.39352 3.39946 3.39385 3.39622 3.39518 3.39564
-20 3.39281 3.40012 3.39369 3.39640 3.3951 3.39576
-30 3.39182 3.40095 3.39348 3.39660 3.395 3.39588
-40 3.39032 3.40203 3.39325 3.39684 3.39486 3.39604
-50 3.38785 3.40315 3.39298 3.39711 3.39468 3.39621
-60 -56dB @
3.38376
3.40425 3.39266 3.39750 3.39442 3.39635
-70 - 3.40532 3.39246 3.39763 3.39402 3.39646
-80 - - 3.39229 3.39785 -76dB @
3.39289
3.39652
Average
stopband
-60dB -75dB -70dB
Notes Four crystals. Significant
spurious responses at
3.54MHz, 3.575MHz and
3.688MHz.
Six crystals. Slight spurious
responses on the HF side.
None worse than -70dB.
Four crystals. Spurious
responses on the HF side.
None worse than -50dB.
Table 10. Heathkit Crystal Filter Table
a) All filters were terminated with 2000 and showed ripple values of not more than
2dB.
b) All frequencies in MHz.
c) The later SSB filter p/n 404-283 was also measured and showed similar results to
404-200.
d) All filters showed some signs of attenuation notches each side of the main response
somewhere between -60dB and -85dB.
e) All filters were also tested using L networks to match them to a 50 environment and
this allowed the passband ripple to be reduced to about 1dB suggesting that there was
some small, probably capacitive, reactance in the 2000 test jig.
f) Health warning - only one filter of each type was tested.
Heathkit Filters Page 102
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