21-08-2016, 11:07 AM
Next one out the box, and an interesting one. At first glance some sort of RF generator but now I'm not so sure but maybe I'm looking too hard at it.
Four bays, nice n easy. Centre bay has a freq counter LCD module, nothing special there other than the display freewheels in use so suspect some wiring is shot. There is also a BNC outlet. LCD unit chip is an MSL2318RS chip. The counter monitors the output from the left hand bay by tapping into the base of the BNC plug.
Centre lower bay contains a 6 volt battery pack and a 555 generator to produce a pulse from quarter second to one second which is fed into the freq counter to conduct spot samples. That bit works well. Knob on left of lower centre panel feeds into right hand unit. Somebody has kindly writted on back "Switch to FM Disc Osc From Freq Centre".
Left hand bay is interesting. Rotary switch selects frequency from 370khz to 30mhz which is fine tuned by the silver knob. There is an AM/FM slide switch and a combines power/volume knob. At the bottom two plug points and a BNC outlet. Inside standard RC circuit using toko coils fro frequency ranges.
Right hand by has a rotary switch for frequency, 150hz to 150khz, fine tuned by the silver knob. Sine/Square slide switch and a combined power/volume control knob. At the bottom two plug points for outlet. Inside of interest, a double ganged 10k pot for fine frequency adjust. Three circuit boards, the first has a HCF4069UBE chip, the second has the timing caps, but the third board has an LF351 and an unidentified glass tube approx 1.5 inch long with two wires emerging from its base. This whole unit output feeds directly to the left had module.
The battery pack holder was shot and has been replaced to get power up for testing.
Four bays, nice n easy. Centre bay has a freq counter LCD module, nothing special there other than the display freewheels in use so suspect some wiring is shot. There is also a BNC outlet. LCD unit chip is an MSL2318RS chip. The counter monitors the output from the left hand bay by tapping into the base of the BNC plug.
Centre lower bay contains a 6 volt battery pack and a 555 generator to produce a pulse from quarter second to one second which is fed into the freq counter to conduct spot samples. That bit works well. Knob on left of lower centre panel feeds into right hand unit. Somebody has kindly writted on back "Switch to FM Disc Osc From Freq Centre".
Left hand bay is interesting. Rotary switch selects frequency from 370khz to 30mhz which is fine tuned by the silver knob. There is an AM/FM slide switch and a combines power/volume knob. At the bottom two plug points and a BNC outlet. Inside standard RC circuit using toko coils fro frequency ranges.
Right hand by has a rotary switch for frequency, 150hz to 150khz, fine tuned by the silver knob. Sine/Square slide switch and a combined power/volume control knob. At the bottom two plug points for outlet. Inside of interest, a double ganged 10k pot for fine frequency adjust. Three circuit boards, the first has a HCF4069UBE chip, the second has the timing caps, but the third board has an LF351 and an unidentified glass tube approx 1.5 inch long with two wires emerging from its base. This whole unit output feeds directly to the left had module.
The battery pack holder was shot and has been replaced to get power up for testing.
