{Collins} 516F-2 & others voltage regulation



Hi All,
firstly , the 30S-1 linear has a STEP START for the plate transfomer primary.
This is a progressive or staged energisation as opposed to the whole circuit being powered up in one hit.
A  time controlled relay is utilised for this purpose.
when pressing the black plate "on" button you should hear two  relay clunks in quick succesion (around1/2  second intervil).
If you detect only one ,this means that the R/C control circuit probably has a dried out electrolytic capacitor.
The set will continue to power up OK for a while in this state, but you are damaging the step start relay and it will soon need replacing.
Particularly if the plate transformer primaries are strapped for 115VAC as opposed to 230VAC.
The 516F-2 supply does not and can not utilise this.
Nevertheless a relay can be fitted to carry the start in rush load whilst protecting the transmitter's on/off switch from arcing errosion.
There are 2 methods of regulating the 800VDC circuit in the 516F-2.
Firstly the two  25K bleeder resistors.
Secondly and more importantly the 120 HERTZ tuned L/C circuit utlising L1 (8 henries) and C1 (0.05Uf)
This circuit loads down the HV circuit when off load whilst presenting minimal loss when on load from the transmitter and is very effective.
this system has been used by collins in the KW-1,KWS-1,30S-1 and various supplies.
To date I have found 4 remedies for high off load voltage in the 516F-2.
1) replace C1
2) tighten up the bolts on the choke laminations.
3) Check and or replace the bleed resistors R4 & R5
4) place variac in AC supply input and ensure 115/230VAC.
Hope this helps out.
73 from VK4VN





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