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series or other modulation types

Nov 7th 2015, 21:16

M0ELS

Joined: Sep 21st 2013, 09:10
Total Topics: 0
Total Posts: 0
I have an old "chatterbox transceiver" solid state and am looking for advice on how to connect an AM modulator to the small amp pcb with 20w output. The am uses a pair of RD15HVF1 devices. I was think along the lines of using a small audio transformer with a centre tap secondary connected to the supply voltage and the other end "floating". The centre tap will connect to the modulator cao an electrolytic cap. The primary side connects to the mic and gnd. Has anyone got any tips or ideas on other types of ways of getting AM audio into these devices.

73
John
Nov 9th 2015, 18:41

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

The modulation signal adds and subtracts with the supply voltage--you typically need to replace the 12 volt devices with 24 volt ones to handle the added voltage stress created by the modulation signal.

Zack W1VT
ARRL Senior Lab Engineer
Nov 26th 2015, 20:38

M0ELS

Joined: Sep 21st 2013, 09:10
Total Topics: 0
Total Posts: 0
ok, so this is not good as I don't want to change those devices for one's with a higher drain voltage. Are there any resources where I can read up on this subject, related to mosfet devices. Looking through some books, its looks as if I will have to modulate the driver as well.

73
John

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