Rockwell Collins Hf-8010 Hi Fi modification
Modification for Full DSB AM
On HF-80 2-channel Exciters
Normally, the AM mode on the exciter is AME (USB with a re-inserted
carrier). There are jumpers soldered on square pins on the Channel A IF
card (637-2651-xxx). These jumpers determine which filter is selected for
the various modes. The Option Filter card (637-2515-xxx) may also be used
“piggy-back” on the Exciter Channel A IF card and provides more filter options
and more strapping options.
There are two ways to modify the Channel A IF card for Full DSB AM.
Method 1 does not rely on the Option Filter card being present. The AM
signal passes through the 16 kHz bandwidth pad. Thus, the bandwidth of the
transmitted signal will be 16 kHz wide unless limited by external audio
filtering of the modulating signal.
Method 2 is very similar to Method 1 except the AM signal is filtered by a
mechanical filter on the Option Filter Card. Normally, this is a 5 or 6
kHz BW filter in the FL3 position, but other bandwidth filters could be
installed as long as they are centered on the 450 kHz IF frequency.
Note: the modifications described below are designed for minimal
invasiveness so the card can easily be restored to original configuration if
desired later.
Method 1 – AM using the 16 kHz pad
1. Cut pin 1 of U10 as close as possible to the pc board.
2. Solder a jumper wire connecting U10-1 to U10-2.
3. Remove original jumper between jumper pins 3 & 2.
4. Solder an AWG #26 wire from pc board edge connector
pin 35 (it has a thru-hold pad very close to pin 35).
5. Connect the other end of the #26 wire to jumper pin 2.
Method 2 – AM using the FL3 on the Option Filter card
1. Same as above.
2. Same as above.
3. Same as above.
4. Same as above.
5. Connect the other end of the #26 wire to jumper pin 4.
6. Install desired AM filter in FL3 position on the Option Filter card and correct
components for that filter IAW the Instruction Book Chart.
HF-80 AM Filters:
526-9963-060 – 6.0 kHz bandwidth
526-8323-010 – 5.4 kHz bandwidth
526-8534-010 – 10.0 kHz bandwidth
On HF-80 2-channel Exciters
Normally, the AM mode on the exciter is AME (USB with a re-inserted
carrier). There are jumpers soldered on square pins on the Channel A IF
card (637-2651-xxx). These jumpers determine which filter is selected for
the various modes. The Option Filter card (637-2515-xxx) may also be used
“piggy-back” on the Exciter Channel A IF card and provides more filter options
and more strapping options.
There are two ways to modify the Channel A IF card for Full DSB AM.
Method 1 does not rely on the Option Filter card being present. The AM
signal passes through the 16 kHz bandwidth pad. Thus, the bandwidth of the
transmitted signal will be 16 kHz wide unless limited by external audio
filtering of the modulating signal.
Method 2 is very similar to Method 1 except the AM signal is filtered by a
mechanical filter on the Option Filter Card. Normally, this is a 5 or 6
kHz BW filter in the FL3 position, but other bandwidth filters could be
installed as long as they are centered on the 450 kHz IF frequency.
Note: the modifications described below are designed for minimal
invasiveness so the card can easily be restored to original configuration if
desired later.
Method 1 – AM using the 16 kHz pad
1. Cut pin 1 of U10 as close as possible to the pc board.
2. Solder a jumper wire connecting U10-1 to U10-2.
3. Remove original jumper between jumper pins 3 & 2.
4. Solder an AWG #26 wire from pc board edge connector
pin 35 (it has a thru-hold pad very close to pin 35).
5. Connect the other end of the #26 wire to jumper pin 2.
Method 2 – AM using the FL3 on the Option Filter card
1. Same as above.
2. Same as above.
3. Same as above.
4. Same as above.
5. Connect the other end of the #26 wire to jumper pin 4.
6. Install desired AM filter in FL3 position on the Option Filter card and correct
components for that filter IAW the Instruction Book Chart.
HF-80 AM Filters:
526-9963-060 – 6.0 kHz bandwidth
526-8323-010 – 5.4 kHz bandwidth
526-8534-010 – 10.0 kHz bandwidth