Heath receiver performance numbers

[Mark S Graalman]

  Just for the sake of comparison, I've measured the
MDS (minimum discernable signal), TTDR (two-tone
dynamic range), and BDR (Blocking dynamic range)
of a few Heath receivers. Now there are some REAL
numbers to use in comparison to other rigs.
 The numbers for the SB-303 and SB-104 were
measured by Sherwood Engineering, the rest where
measured by me here in my shop.

SB-301:
MDS  -138 dBm
TTDR (20 Khz spacing)  83 dB
BDR (20 Khz spacing)  118 dB

SB-303:
MDS  -135 dBm
TTDR (20 Khz spacing) 66 dB
BDR (100 Khz spacing)  104 dB

SB-104
MDS  -123 dBm
TTDR (20 Khz spacing) 79 dB
BDR (100 Khz spacing) 92 dB

HW-101  (JKR/JCJ optimizing mods installed)
MDS  -138 dBm
TTDR (20 Khz spacing) 82 dB
BDR (20 Khz spacing) 95 dB

HR-1680
MDS  -137
TTDR (20 Khz spacing) 81 dB
BDR (20 Khz spacing) 105 dB

 Since the SB301 and 300 are basically the same unit the
numbers should be about the same, the same would go for the
HW-101 and the SB-102.
 The biggest departure from typical of the era performance in
these rigs is the lousy ultimate rejection of the I.F. filter which
is about 70 dB. It can also be seen that the SB-303 has way
too much gain, the SB-300/301 is actually a much better unit
in terms of overload resistance.
 Keep in mind also that these numbers were taken on rigs that
are working perfectly and have had a good instrument alignment.

73,  Mark  WB8JKR

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