SRN- 1283

APC 672, 749

Date: June, 1999

Memo To: SRN Mailing List

Deadline: Sept. 30, 1999

From: Radio Product Group / CGISS

Subject: HT750 and HT1250 Buzz or Noise When Receiving a TPL Code

The user may experience either of the following when listening to transmissions with TPL signaling.

1. Excessive and noticeable background 'buzz' in the receive audio.
2. A perceived decrease in receiver sensitivity.

All Professional Series HT750 and HT1250 portables.

An internal frequency used in the receiver circuitry (the base band offset frequency) interacts with the PL of the incoming signal. The radio software changes the offset frequency to eliminate this interaction for TPL decode for the TPL programmed for that receive personality. When the radio is not programmed to decode the TPL, i.e. in the monitor mode, the offset frequency may interact if the TPL is between 95 and 135 Hz. Other known cases of Base band Offset noise occur during multiple TPL/DPL conditions, such as community repeater operation, and when using the radios for TPL decode along with QCII or MDC signaling.

The base band offset frequency must be changed to a frequency more than 20 Hz away from the incoming TPL. This offset frequency can be changed by use of Tuner R01.01.03. This tuner can be ordered either on diskette or email by filling out the information on the last page of this bulletin and faxing it to 954-723-4470. In the near future this new version of Tuner will be included in the Customer Programming Software, CPS. The first version of the CPS that the R01.01.03 Tuner will be provided with is version R02.00.00.

No labor Warranty is intended or implied.

• For international shipments contact your Motorola Regional Service provider