1.0 General Description

Transcription

1 1.0 General Description Figure 1 - Plug-N-Play Noise Blanker for the Collins 75S-1 Series The Collins Noise Blanker is designed to be a Plug-N-Play accessory for the Collins 75S-1 series. The Noise Blanker is mounted to the receiver s existing hardware with no electrical or mechanical modification to the receiver is made. The noise blanker input/output signals, and the power from the receiver, are provided with a special plug-in adapter for V4, the receiver s second mixer. The noise blanker s Threshold control is mounted on a nylon plug, placed in the rear right access hole, at the upper left side of the enclosure. The installation is quick and simple. The noise blanker is connected to the receiver s signal path at all times. The noise pulse amplifier, and pulse forming network is not enabled until the rear panel mounted Threshold control is adjusted. The gain of the controlled IF amplifier is set with the IF gain adjust, which is adjusted for unity gain. The signal from the receiver s Variable IF is connected to the Noise Blanker through a J-FET source follower. This high impedance input minimizes loading the receiver s 1 st mixer output. The signal from the JFET follower is split into two paths. One path is coupled to the IF Amplifier and the other to the Noise Pulse amplifier and detector. Both amplifiers have a pass-band of approximately 300 KHz matching that of the receiver. Noise pulses from the Noise Amplifier are detected and converted to square positive pulses, whose width is proportional to the detected noise pulse at a repletion rate of 10 to 2000 pulses per second, and a pulse width of 1 to 250 µsec. This blanking pulse controls the output of the controlled IF amplifier. When a blanking pulse is generated, the controlled IF amplifier is turned off or blanked for the duration of the pulse with an effective blanking up to 50dB. Page 1 of 6

2 2.0 Pre-Installation Procedure Before installing the Plug-N-Play Noise Blanker, it is suggested that you become familiar with the 75S-1 documentation, and the chassis component layout. It is assumed that the receiver is functioning properly, and in good working condition. If not, a thorough checkout may be called for before installing the noise blanker. Figure 2 - The 75S-1 Series Front Panel and Controls Figure 2 is a picture of a 75S-1 front panel and controls. Connect the AC line cord, and turn the power on. Allow a warm-up period of 5 minutes for stabilization. Connect the speaker to the audio output RCA jack. The antenna is not used during the installation, and is not connected. After the 5 minute warm-up period, use the following procedure to determine the75s-1 s overall gain so that it can be matched when the noise blanker is installed. 1. Set the OFF-STBY-OPR-CAL switch in the CAL position. 2. Select 14.2 MHz on the BAND switch. 3. Set the RF GAIN control for max gain (fully clock-wise) and the AF GAIN to a comfortable level. 4. If the optional Collins Noise Blanker is installed, set the NB Gain to OFF. 5. Set the MODE to USB. 6. Set the BFO to OFF. 7. Set the VFO in the 0.0 position as read on the dial. 8. Adjust the PRESELECTOR for maximum S meter reading and RECORD this value. It will used later to adjust the noise blanker gain to match this value. The object of this procedure is to determine the overall gain of the receiver, and after the noise blanker has been installed this procedure will be repeated to set the noise blanker unity gain IF amplifier. 9. Un-plug the AC power from the receiver before continuing with the noise blanker installation. Page 2 of 6

3 3.0 Installing the Plug-N-Play Noise Blanker in the 75S-1 Receiver Series Figure 3 - Noise Blanket Kit for 75S-1 The Noise Blanker Kit includes the printed circuit board, hardware, and harness/cable assembly. The installation procedure is as follows: 1. Remove the 2 nd mixer tube, V3 (6EA8) (Fig. 3). 2. Locate the two (2) 6-32 studs between the Pre-Selector and IF transformers (Fig. 3). 3. Mount the (2) 6-32 x 1 inch stand-offs on the two studs (Fig. 4). Figure 3 Figure 4 Page 3 of 6

4 4. Insert connector end of harness into rear access hole of enclosure (left side viewing from the rear). Press the plastic plug into the access hole for a snug fit (Fig. 5 & 6). Figure 5 Figure 6 5. Press the tube socket adapter into V3, and route the harness as shown (Fig. 7 & 8) Figure 7 Figure 8 Figure 9 Figure Insert harness plug into receptacle on PCB (Fig 9). 7. Secure PCB to standoffs with screws (Fig 10). Page 4 of 6

5 8. The completed installation (Fig 11). Figure 11 Figure Calibration The final step is to adjust the Noise Blanker gain to match the calibrator S value reading, which was established during the Pre-Installation Procedure. 1. Set the OFF-STBY-OPR-CAL switch in the CAL position. 2. Select 14.2 MHz on the BAND switch. 3. Set the RF GAIN control for max gain (fully clock-wise) and the AF GAIN to a comfortable level. 4. Set the REJECTION TUNING to OFF. 5. Set the MODE to USB. 6. Set the BFO to OFF. 7. Set the VFO in the 0.0 position as read on the dial. 8. Adjust the PRESELECTOR for maximum S meter reading value. 9. Adjust the gain control (R7) (Fig 12) on the Noise Blanker for the S meter value established in the Pre-Installation Procedure (Section 2). This completes the installation and alignment of the 75S-1-2/3 Plug-N-Play Noise Blanker. 5.0 Operation The Noise Blanker is enabled or disabled with the Threshold control mounted on the enclosure rear panel. Fine tuning of the blanker can be made by tuning to a station that has noise, and adjusting the Threshold control for the desired blanking effect. It s that simple. A solid state noise blanker has been installed to your Collins 75S-1 without circuit or mechanical modifications. 6.0 Terms and Conditions of Use The materials contained in this document could contain technical inaccuracies or typographical errors. Changes are periodically added to the information herein. Wynn Works, LLC may make improvements and/or changes in this documents, and the product(s), and technical specifications described in this document at any time without notice. Wynn Works, LLC also assumes no responsibility, and shall not be liable for, any damages to, or viruses that may infect, your computer equipment or other property on account of your access to, use of, or browsing within this document, or your downloading of any materials, data, text, images, video, or audio from this document. In no event shall Wynn Works, LLC be liable for any incidental or consequential damages, lost profits, or lost data or any indirect damages, even if Wynn Works, LLC has been informed of the possibility thereof Wynn Works, LLC. Page 5 of 6

6 We at Wynn Works, LLC are interested in your experiences with our products, and welcome your comments. If you have any questions, or require any assistance, we can be contacted during normal business hours: Monday through Friday 9:00 AM to 5:00 PM Pacific Time. Wynn Works, LLC. 299 Old County Road, Suite 2 San Carlos, CA Tel: (650) Fax:(650) support@wynnwrks.com Doc #:Noise Blanker for Collins 75S-1 rev 2.doc Page 6 of 6