Analisis de equipos por W8JI

Model (in some cases serial included) MDS 2kHz  BDR 10kHz BDR 2kHz IMDR 10kHz IMDR
1 R4C heavy mod. Experimental. 

See note 5

-143 127 131 118 119 
2 R4C 17816 med mod. 

See note 4

-140 96 115 92 103 
3 TenTec Orion -129 98 100 92 92
4 FT1000D/W8JI mods -136 73 87 89 88
5 TS-870 Inrad 400Hz IF filter mod (AIP) -139

(-125)

74

(82)

94

(98)

86

(81)

90

(91)

6 FT1000MK V

W8JI mods

-131 80 89 85 90
7 IC-751A -140 83.5 98 79 91
8 IC-7800 -127 80  98 78 88@5 kHz
9 FT1000MP 8N370165 -135 73.5 84 62*      75.5**

note 1

70.5*  80**  

note 1

10 FT1000D -134 68 85 72 81
11 R4C S/N 22291 stock -139 80 116 68 86 note3
12 IC-756 PRO -133 N/A 78 67 77
13 FT1000MK V stock -131 74 86 60 note1A 77 note 1A
14 R4C S/N 17816 stock -132 57 109 48 82 note2

 

Note 1: The FT1000MP has the same inherent problem as the FT1000 and FT1000D. A noise-blanker amplifier FET is left on even when the noise blanker is turned off with front panel NB and NB-W switches. This FET connects directly to the IF, and overloads when strong signals are present. Unlike the FT1000 and FT1000D, the front panel noise blanker level control affects the FT1000MP IMD performance. * is with the NB gain control fully advanced, ** is with the NB gain control fully off. In ALL cases the NB off-on switch is OFF!!

Note 1A: Yaesu copied the same basic NB from the FT1000D, and so this radio also has a NB problem even when the NB is switched off. This test was with NB gain menu set for minimum gain. The radio is worse when NB gain is increased in the NB gain menu.   

Note 2: This is a MOSFET 2nd mixer R4C, aligned and in good shape but with no changes. This receiver is almost useless for weak signal CW work of any kind because of poor IM performance and filter blow-by.  

Note 3: This is a tube 2nd mixer R4C, aligned and in good shape but with no changes. This receiver is almost useless for contesting or crowded bands because of poor IM performance and bad filter blow-by. 

Note 4: This is the same receiver in note 2, but with the following changes:

  1. Increased screen voltage on RF amplifier to 130 volts.
  2. 6J6 first mixer with oscillator injection increased to 5 volts.
  3. Diode double-balanced 2nd mixer with +10dBm injection.
  4. 10dB of gain removed from first mixer and first IF and redistributed behind the narrow filter.
  5. Sherwood Engineering 600Hz roofing filter.
  6. New AGC system. After narrow filter only, no AGC on front end.

Note 5: Gutted and rebuilt with solid-state double balanced high-level mixers. No vacuum tubes in signal path. Sherwood 600Hz roofing filter. Experimental receiver for full-duplex operation on 160 meters. This receiver allows me to hear weak DX while I am transmitting, as long as they are a few kHz off frequency.