TS-520S NO ALC/Transmit - ModsAndRepairs Forum at eHam.net

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eHam.net Forum : ModsAndRepairs : TS-520S NO ALC/Transmit

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TS-520S NO ALC/Transmit	Reply
by WB4BYQ on October 9, 2009	Mail this to a friend!
I am working on my ts-520s that will not transmit in phone or cw. i have no alc in phone. no power in cw. the bias works at 60 mills, the receiver works in phone and cw. tubes are good and have been sub. i think that i have a power supply problem. the frequency readout shows the correct frequency. has anyone seen this problem?

RE: TS-520S NO ALC/Transmit	Reply
by KA5IPF on October 9, 2009	Mail this to a friend!
Do you have ALC in CW mode? If so, is the SG switch on the back "On" or "Off"??

RE: TS-520S NO ALC/Transmit	Reply
by K4DPK on October 9, 2009	Mail this to a friend!
Try wiggling the bandswitch. They sometimes get out of register. Move slowly, almost to the next band, then back to where you want to operate and see what happens. Phil C. Sr. k4dpk

RE: TS-520S NO ALC/Transmit	Reply
by KE4DRN on October 9, 2009	Mail this to a friend!
hi Richard, can you please check the HV meter reading, if it is half the normal value one of the hf filter caps is bad. you may have a broken or almost broken shaft coupler. join other ts-5xx and 8xx fans here http://groups.yahoo.com/group/TS-520_820_530_830/ 73 james

RE: TS-520S NO ALC/Transmit	Reply
by K4DPK on October 9, 2009	Mail this to a friend!
His static plate current (incorrectly called the bias) looks right, so his plate voltage is probably OK. The reason the bandswitch might be out of register is the bandswitch coupling. Those nylon couplings crack across the set-screw holes and start slipping on the bandswitch shaft. If that is the problem, you can swap it for the one on the loading capacitor. Phil C. Sr. k4dpk

RE: TS-520S NO ALC/Transmit	Reply
by KE4DRN on October 11, 2009	Mail this to a friend!
hi Phil, yes, easy to repair those couplers, they can be replaced with brass coupler from hardware store or lowe's in the parts drawers. many of us have replaced them on the ts-520 forum and no problem to use brass since the shafts are grounded at the cage and where they pass the front panel. good cleaning also is in order and check the ground screws on pc boards, this can 'fix' many problems since the radio has common grounds to the boards. 73 james

RE: TS-520S NO ALC/Transmit	Reply
by WB2WIK on October 11, 2009	Mail this to a friend!
Isn't it fun when people post stuff like this and then never return?

RE: TS-520S NO ALC/Transmit	Reply
by K4DPK on October 11, 2009	Mail this to a friend!
Hey Steve... Yes, I was about to say that. It seems we get left hanging a lot and never do learn the outcome. There is actually more the gentleman needs to know, like how to put the switch sections back in register after he loosens that coupling. The value in letting us know lies in helping other folks later who have the same problem. Plus, it'd make us feel as if we didn't completely waste our time. Phil C. Sr. k4dpk

RE: TS-520S NO ALC/Transmit	Reply
by WB4BYQ on October 12, 2009	Mail this to a friend!
Thanks for the help. i found the problem on sat with my scope. Q1 (3SK41) dual-gate mosfet was defective. replaced with a spare 3SK41 that i had. there was no drive, alc, no plate current, no power out either in cw or phone. the bias was there. receiver was ok, frequency was ok on the dg-5, carrier, het, vfo were being generated and mixed. for parts see this web site k4eaa. http://www.k4eaa.com/ he has brass couplers, and other parts. for other parts see on qrz.com ke5ftf. i have replace the coupler in the ts-820s with a nylon spacer from lowes hardware dept by redrilling the hole,cutting, and setting the set screws. but i like the brass couplers form k4eaa. best of dx, God Bless wb4byq

RE: TS-520S NO ALC/Transmit	Reply
by WB4BYQ on October 12, 2009	Mail this to a friend!
The Q1 mosfet 3sk41 was on the RF Unit board, which drives the 12BY7AGT. wb4byq

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