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Old 04-10-2017, 3:33 AM
JimVK2JHG JimVK2JHG is offline
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Join Date: Apr 2017
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Hi Bill

LPF7 installation notes for the bg7sgm are below. Noting in your higher density environment a BPF centred on the selected repeater or even an in line cavity filter maybe more appropriate (400mHz cavity filters are on taobao for around $40).

1. Build up the minikits LPF7 per instructions, fit an sma socket to the input end per the **ver illustration attached.

2. Open up the bg7sgm and drill two holes through the heatsink aligned with two of the LPF7 mounting holes (see **hor illustration attached).

3. Referring to the attached illustrations, using suitable screws and nylon standoffs, mount the filter on the heatsink as illustrated ensuring there is just sufficient separation between the underside of the filter and the top of the thermal switch. Selective use of foam and glue can be applied to mechanically stabilise the LPF7 installation against vibration etc.

4. Desolder the bg7sgm antenna output lead, and resolder it to the output side of the filter.

5. Prepare a 21cm length of sma coax with right angle plug (21cm length of the outer shield - allow another 7mm of inner conductor), for use as the filter input cable.

6. Per the **ver illustration, solder the filter input cable to the now vacant amplifier board coax output.

7. Attach the plug of this cable to the input socket of the LPF7.

8. Adjust the routing of the LPF input cable to keep it as far as possible away from the output side of the filter (see illustrations for general arrangement).

Check the work and the job is done.

Note that we found it is important for the filter to operate efficiently, the input and output cables to the LPF need to be routed so they are as far apart as the layout of the case allows.

The two .jpgs should be attached.
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