02-07-2018, 08:44 PM
Hi Trevor,
Info from the Trader sheet 1632/T248.From the Trader service sheet, a description on how the solenoids operate the switch lever:
"S3 and S6 form part of the changeover assembly, and accordingly they are b and a to indicate that they close on 625 and 405 respectively as are all the other system switches. It follows therefore that with the selector at a VHF channel, as shown in the diagram, S6a will be closed and S3b open.
The system switch assembly is operated by solenoids, forming a magnetic relay, which pulls the armature in opposing directions and the solenoid coils GH1 and CH2 are used as smoothing chokes on both systems, but one of them is bypassed during the actual changeover operation.
If the selector is turned from the VHF channels to the UHF stud, with S6a still closed, CH2 will be short-circuited, HT current will by-pass it, and it will cease to be energised. The "pull" on CH1 will the cause an armature linked to the system switch assembly to move over to the UHF position, closing all the "b" switches. It can be seen correspondingly that if the selector subsequently turned to any VHF channel S3b closed at the time, CH1 will be shot-circuited. It's "pull" will cease to hold the armature and as CH1 is now energised it will pull the armature in the opposite way and move the system switch to 405
The control switch unit is connected in series with S6a on the other. But when it is set to UHF S6a automatically opens and when it is set to a VHF channel S3b automatically opens.
As a result, although one choke is short-circuited during the changeover, both are energised as soon as changeover is effected and assist in smoothing the HT current. The armature remains passive while both chokes are energised; it only moves when the magnetic of one choke collapses."
No mention of the function of the capacitor C65.
Ill post up an extract from the circuit diagram as it appears in the Trader sheet.
Geordie McBoyne.
Info from the Trader sheet 1632/T248.From the Trader service sheet, a description on how the solenoids operate the switch lever:
"S3 and S6 form part of the changeover assembly, and accordingly they are b and a to indicate that they close on 625 and 405 respectively as are all the other system switches. It follows therefore that with the selector at a VHF channel, as shown in the diagram, S6a will be closed and S3b open.
The system switch assembly is operated by solenoids, forming a magnetic relay, which pulls the armature in opposing directions and the solenoid coils GH1 and CH2 are used as smoothing chokes on both systems, but one of them is bypassed during the actual changeover operation.
If the selector is turned from the VHF channels to the UHF stud, with S6a still closed, CH2 will be short-circuited, HT current will by-pass it, and it will cease to be energised. The "pull" on CH1 will the cause an armature linked to the system switch assembly to move over to the UHF position, closing all the "b" switches. It can be seen correspondingly that if the selector subsequently turned to any VHF channel S3b closed at the time, CH1 will be shot-circuited. It's "pull" will cease to hold the armature and as CH1 is now energised it will pull the armature in the opposite way and move the system switch to 405
The control switch unit is connected in series with S6a on the other. But when it is set to UHF S6a automatically opens and when it is set to a VHF channel S3b automatically opens.
As a result, although one choke is short-circuited during the changeover, both are energised as soon as changeover is effected and assist in smoothing the HT current. The armature remains passive while both chokes are energised; it only moves when the magnetic of one choke collapses."
No mention of the function of the capacitor C65.
Ill post up an extract from the circuit diagram as it appears in the Trader sheet.
Geordie McBoyne.
