Dismantling the BE515

Without a service manual, or circuit diagrams, im pretty much working blind with the SARBE-6.  However, years of servicing public safety radios, plus the service manual for the older, but in many ways similar SARBE-5, means I do have a reasonable idea how to go about it.

The electronics package of the SARBE-6 is made up of a main PCB, plus a couple of smaller plug in modules. The main board fills the whole of the internal space, and is held secure onto a pair of threaded studs. Because the only externally mounted parts are the antenna socket and the battery connection, it 'should' be a simple case of lifting the electronics gently out, after unsoldering the antenna.

A great feature of modern smart phones is the ability to photograph a circuit just before carrying out any work, and immediately annotate it, so you have a record of what was done. This helps when rebuilding, but is also brilliant for spotting where you went wrong!

Antenna connects to straight reed leg

The problem is getting it up over the threaded studs! There is very little clearance around them. Now, im sure in the Burndept factory they will have had a jig for this! But I have no such, and must rely on carefully prising the board up using dental picks and jewelers screwdrivers.

The battery and transducer (loudspeaker/microphone) connections also need desoldering. It would be a shame to cut the intricate cable loom lacing, plus, there may be reasons that the wires follow the paths they do (RF stability etc), so I will try and extract them from the loom, with the hope of being able to carefully reinsert them later.

Brown transducer wire to right hand pin

Battery connections

With the electronics removed, I should be able to work out the switching sequences, and from that devolve a plan to put the set into permanent receive mode.

As it turned out, the transducer and battery wires were held to the loom in only two places, and were very simple to remove. I now have the electronics package out of the case, and can start working on the modification plan.

casing showing transducer

Electronics top side

Electronics under side, Tx crystal top left

Tx/Rx switching

Of course the fastest way to kill the Tx would be to simply pull the crystal, which happens to be socketed! But that would leave a powered oscillator and PA, which could cause problems.