KENWOOD TS-950SD HF Transceiver Instruction Manual
- June 17, 2024
- KENWOOD
Table of Contents
KENWOOD TS-950SD HF Transceiver
Product Information
ASB-982 Service Bulletin
Amateur Radio Division
The ASB-982 Service Bulletin is a modification for the TS-950S/SD amateur
radio transceiver. The modification addresses a transmit image issue at
18.115MHz that distorts the carrier received by the other station. By
installing a trap on the 455KHz I.F., the image level can be lowered from
-30dB to better than -40 dB. The modification requires the installation of
specific parts and adjustments to ensure optimal performance.
Specifications
- Required Parts:
- 4pF Trimmer Capacitor – Part Number: C05-0308-05
- 40pF Trimmer Capacitor – Part Number: C05-0309-05
- 2.2uH Coil – Part Number: L40-2292-14
- Time Required: 1 hour or less
- Warranty: This modification is covered under the 1-year warranty
Product Usage Instruction
Modification Instructions
- Disconnect the power cord and antenna from the TS-950S/SD.
- Remove the top and bottom covers of the transceiver by unscrewing the 18 screws.
- Locate the I.F. board on the bottom of the transceiver. This board is positioned at the back right among the four boards on the bottom.
- Find L36 near connector CN17 on the I.F. board.
- Install and solder a 4pF trimmer capacitor across L36.
- Install a 2.2uH coil and a 40pF trimmer capacitor in series from the output of L36 to the ground. The can of L31 can be used as the ground connection.
- Push the wire harness around the I.F. board toward the transceiver chassis.
- Assemble the transceiver by reattaching the top and bottom covers using the 18 screws.
Alignment Instructions
- Connect the TS-950S/SD to a power meter and a 50-ohm load.
- If you are working on the TS-950S Digital, connect the DSP cables on the bottom cover to the back panel.
- In CW mode, adjust the front panel power control to 150W while ensuring the ALC (Automatic Level Control) level is at the starting point on the meter. This will create the highest image level condition.
- Using a monitor receiver with narrow filters installed and AGC (Automatic Gain Control) set to off, tune the receiver to the image frequency (18.115MHz).
- Alternately adjust the two trimmer capacitors until the image cannot be heard. This procedure may need to be repeated several times.
FAQ
-
Q: What is the purpose of this modification?
A: The modification aims to lower the transmit image level at 18.115MHz, which causes distortion on the received carrier. -
Q: How long does the modification take?
A: The modification should take approximately 1 hour or less to complete. -
Q: Is the modification covered under warranty?
A: Yes, this modification is covered under the 1-year warranty.
Introduction
Some TS-950SD owners have reported a transmit image at 18.115MHz that causes the receiving station to hear distortion on the carrier. If the operating frequency is shifted 3KHz above or below 18.115MHz, the image disappears. This modification will lower the image level from -30dB (worse case) to better than -40dB by installing a trap on the 455KHz I.F.
REQUIRED PARTS
- 4pF TRIMMER CAPACITOR C05-0308-05
- 40pF TRIMMER CAPACITOR C05-0309-05
- 2.2uH COIL L40-2292-14
MODIFICATION
- Disconnect the power cord and antenna.
- Remove the top and bottom covers (18 screws).
- Locate the I.F. board on the bottom of the transceiver. This is the back right board of the 4 boards on the bottom of the transceiver. Figure 1
- Locate L36 by connector CN17 on the I.F. board. Figure 2
- Install and solder into place a 4pF trimmer capacitor across L36. Figure 3
- Install a 2.2uH coil and 40pF trimmer capacitor in series from the output of L36 to the ground. The can of L31 can be used for ground. Figure 3
ALIGNMENT
-
Connect the TS-950S/SD to a power meter and 50 ohm load.
-
If you are working on the TS-950S Digital, connect the DSP cables on the bottom cover to the back panel.
This modification is covered under the 1-year warranty. The time required for this modification is 1 hr. or less. (C) 020691EWP.
In the CW mode, adjust the front panel power control for 150W while the ALC level is just at the starting point on the meter. This will create the highest image level condition. -
Using a monitor receiver with narrow filters installed and AGC set to off, tune the receiver to the image frequency.
-
Alternately adjust the two trimmer capacitors until the image cannot be heard. This procedure may need to be repeated several times.
-
Push the wire harness around the I.F. board toward the chassis of the transceiver.
-
Assemble the transceiver.
Copyright (C) 02/06/91 EWP for Kenwood U.S.A. Corporation.