Partially deaf PCR-1000

[N8YX]

Anyone else ever run across one of these which lacks sensitivity even after the BPF adjustment routines are performed via software?

As an example, a 1mV amplitude signal at 149.9700 MHz gives a sample S-level value of 128 when applied to the unit's Antenna connector; this seen in the EX2099 program's dashboard. Knock the generator amplitude down to 0.1mV (not uV, mind you) and the received signal gets very noisy. With just about any other VHF FM receiver I own, even a 20uV signal applied to the Antenna connector results in full quieting and a noticeable S-meter reading/derived AGC voltage.

If I use the generator to apply a signal to "CP5" - just ahead of the 1st Mixer - a little increase (but not much) in signal level is noticed. This leads me to believe something's up with the BPF section of the RF Unit. The receiver appears deaf everywhere - not just on one band.

Suggestions and observations welcomed.

73 - Fred, N8YX

 

[iMONITOR]

I don't recall the details but another member here on RR had a post about either the PCR-1000 or possibly PCR-1500 having a few capacitors go bad that needed to be replaced. Could be related consider their age. Look through the Icom threads back 2 or 3 months.

 

[SigIntel8600]

Anyone else ever run across one of these which lacks sensitivity even after the BPF adjustment routines are performed via software?

As an example, a 1mV amplitude signal at 149.9700 MHz gives a sample S-level value of 128 when applied to the unit's Antenna connector; this seen in the EX2099 program's dashboard. Knock the generator amplitude down to 0.1mV (not uV, mind you) and the received signal gets very noisy. With just about any other VHF FM receiver I own, even a 20uV signal applied to the Antenna connector results in full quieting and a noticeable S-meter reading/derived AGC voltage.

If I use the generator to apply a signal to "CP5" - just ahead of the 1st Mixer - a little increase (but not much) in signal level is noticed. This leads me to believe something's up with the BPF section of the RF Unit. The receiver appears deaf everywhere - not just on one band.

Suggestions and observations welcomed.sue.

73 - Fred, N8YX

It may be an EEPROM corruption issue.

PCR1000 off frequency

 

[Ubbe]

You have done the adjustment procedure so the eeprom values are then corrected, if they even where incorrect to begin with. The most common deaf problem are the switch diodes that selects between the different filters and sometimes the first amplifier transistor needs to be replaced. You can do a simple go no-go test of all the diodes in the front end. Perhaps the protection diodes at the antenna port have blown.

/Ubbe

 

[N8YX]

Ubbe,

Are the diodes in question located on the top or the bottom side of the RF Unit?

73 - Fred

 

[Ubbe]

Are the diodes in question located on the top or the bottom side of the RF Unit?

Maybe it shows in the service manual.

PCR1000 service manual

/Ubbe