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Title: ART-13 Power supply question Post by: kc2we on May 06, 2020, 01:29:02 PM In normal operation with original config (AM or CW), no mods, did the dynamotor run all the time (ART-13 unkeyed) as long as the 28 VDC was going to the radio while the mode switch was on? In AM standby mode, unkeyed, should the HV and 400 volt supplies (using a homebrew AC / DC supply) be energized to the radio when the radio is unkeyed? I've seen homebrew supplies do it either way. Not sure what's really correct or if it makes any difference. I was concerned that in AM unkeyed, if the HV was on that the 811A's would draw idle current.
Seth KC2WE Title: Re: ART-13 Power supply question Post by: SM6OID on May 07, 2020, 05:10:02 AM Hi!
In "CW" and "MCW" mode the dynamotor runs all the time, in "VOICE" mode only when PTT is closed. To be correct, PTT is defined as the switch on the mic OR "KEY" os "TS". Title: Re: ART-13 Power supply question Post by: kc2we on May 07, 2020, 10:32:26 AM So, in CW mode the key only keys the 400 Volts (low voltage) while the High Voltage stays on. I'm looking at a way to have to my homebrew power supply operate as if it was a dynamotor.
ST Title: Re: ART-13 Power supply question Post by: SA2CLC on May 07, 2020, 11:30:28 AM It should key both the 400v and HV.
Title: Re: ART-13 Power supply question Post by: SM6OID on May 07, 2020, 01:52:24 PM Hi!
The dynamotor supplies both "high voltages". If it is spinning, you have +400 V for the small tubes and the kV for 811 and 813. Title: Re: ART-13 Power supply question Post by: kc2we on May 07, 2020, 02:56:15 PM OK. Well, I read the tech manual based on input here, and ........ the way I understand things, in CW mode, the dynamotor High and low voltages are available in receive OR transmit. The key line in that mode, just keys K102 which according to the manual keys the +400 volts to the 813 screen and grounds the cathode of the Master Oscillator (VFO) to key the carrier off/on. K102 coil also keys the vacuum T/R relay. In AM mode on receive, the dynamotor is off. The dynamotor starts spinning to make B+ and 400 volts when Push to Talk is closed. This is the same key line. Of course in AM, the VFO cathode is closed as well as the 813 screen voltage is applied at the SAME time. All cleverly designed by Collins by using relays. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
The reason I wanted to get this straight is that I want to used grid blocked keying mod scheme similar to what other conversion articles did in the past. However, before I started conversion, I wanted to make sure it worked as a "stock" radio before making any mods. ST |