K5AM - Collins 51S-1 receiver K5AM       Boatanchor collection      
Collins 51S-1 receiver


Serial number 5508.

History.
1959-1975. Approximate date of manufacture.
Manufacturer: Collins Radio Company, Cedar Rapids, Iowa.
1981. Purchased.
1982. Complete check-out, lube, and alignment.
2017. Check-out and test.

Measurements; January 24, 2017.
HP 8640B, HP 3400A(true RMS), HP 334A.
Sensitivity test A, AM.
Specifications, for 10 dB S+N/N:
     2-30 MHz, 3 V;
     0.5-2 MHz, 15 V;
     0.2-0.5 MHz, 20 V;
Measurements; MHz, V:
     0.5, 0.32
     0.9, 0.46
     1.1, 0.18
     2.2, 0.16
     3.3, 0.18
     4.4, 0.24
     5.5, 0.24
     6.6, 0.46
     7.7, 0.26
     8.8, 0.28
     9.9, 0.26
     10.1, 0.21
     11.2, 0.22
     12.3, 0.24
     13.4, 0.23
     14.5, 0.19
     15.6, 0.19
     16.7, 0.20
     17.8, 0.23
     18.9, 0.18
     19.1, 0.14
     20.2, 0.15
     21.3, 0.13
     22.4, 0.17
     23.5, 0.14
     24.6, 0.15
     25.7, 0.19
     26.8, 0.16
     27.9, 0.16
     28.1, 0.16
     29.2, 0.15
Results: Excellent.
Sensitivity test B, SSB.
Measurements; MHz, MDS.
     1.880, -111
     7.250, -130
     14.200, -136
     21.300, -133
     28.400, -132
Results: Excellent.
Sensitivity test C, CW.
Measurements; MHz, MDS.
     3.025, -138
     10.030, -136
     18.070, -138
     24.900, -138
Results: Excellent.
AF Output THD test.
Specification: less than 10% distortion at 1 watt output, SSB, 100 V.
Test conditions: 3850 kHz, 100 V, 1 watt output.
Measurement: 3.4%.
Results: Excellent.
Calibration test.
Note that the front panel "zero set" allows adjustment for 3 kc.
      1) VFO linearity. Checked each 100 kc point; all within 1 kc.
      2) HFO accuracy. Checked each band; all within 1 kc.
Results: Excellent.
By-ear test, in speaker. Sounds great, SSB, CW, AM.