Fixing Damaged and Abused R218 - Revision history

Gordonp: Gordonp moved page Dealing with the Overheated and Cracked R232 to Fixing Damaged and Abused R218 without leaving a redirect

2020-11-11T20:22:50Z

Gordonp moved page Dealing with the Overheated and Cracked R232 to Fixing Damaged and Abused R218 without leaving a redirect

← Older revision	Revision as of 20:22, 11 November 2020
(No difference)

Gordonp at 22:27, 1 June 2020

2020-06-01T22:27:51Z

← Older revision		Revision as of 22:27, 1 June 2020
Line 15:		Line 15:

	[[Repair\|Back to Repair]]		[[Repair\|Back to Repair]]

			[[Dealing with the RF Output\|On to Dealing with the RF Output]]

Gordonp at 22:26, 1 June 2020

2020-06-01T22:26:49Z

← Older revision		Revision as of 22:26, 1 June 2020
Line 13:		Line 13:

	In this photo, R218 appears in the lower-right corner (on a diagonal). R220 is in the center.		In this photo, R218 appears in the lower-right corner (on a diagonal). R220 is in the center.

			[[Repair\|Back to Repair]]

Gordonp at 22:25, 1 June 2020

2020-06-01T22:25:43Z

← Older revision		Revision as of 22:25, 1 June 2020
Line 12:		Line 12:
	[[File:Underside_relayshelf_tidy.jpg\|500px\|thumb\|center\|Underside View of the Relay Shelf]]		[[File:Underside_relayshelf_tidy.jpg\|500px\|thumb\|center\|Underside View of the Relay Shelf]]

	In this photo, R218 appears in the lower-~~rigth~~ corner (on a diagonal). R220 is ~~right~~ in the center.		In this photo, R218 appears in the lower-right corner (on a diagonal). R220 is in the center.

Gordonp at 22:24, 1 June 2020

2020-06-01T22:24:53Z

← Older revision		Revision as of 22:24, 1 June 2020
Line 9:		Line 9:

	Of note: both R218 and R220 are 5% metal film. They're targetted at the automotive sector, and come with appropriate credentials, a flame-retardant coating, and safety qualifications. Not just your basic resistor :-)		Of note: both R218 and R220 are 5% metal film. They're targetted at the automotive sector, and come with appropriate credentials, a flame-retardant coating, and safety qualifications. Not just your basic resistor :-)

			[[File:Underside_relayshelf_tidy.jpg\|500px\|thumb\|center\|Underside View of the Relay Shelf]]

			In this photo, R218 appears in the lower-rigth corner (on a diagonal). R220 is right in the center.

Gordonp at 22:21, 1 June 2020

2020-06-01T22:21:37Z

← Older revision		Revision as of 22:21, 1 June 2020
Line 8:		Line 8:
	While I was in the neighbourhood, I replaced the divider companion R220 with a new 2-watt 3k3 resistor.		While I was in the neighbourhood, I replaced the divider companion R220 with a new 2-watt 3k3 resistor.

	Of note: both R218 and R220 are 5% metal film. They're targetted at the automotive sector, and come with appropriate credentials, a flame-retardant coating, and safety qualifications.		Of note: both R218 and R220 are 5% metal film. They're targetted at the automotive sector, and come with appropriate credentials, a flame-retardant coating, and safety qualifications. Not just your basic resistor :-)

Gordonp at 22:21, 1 June 2020

2020-06-01T22:21:19Z

← Older revision		Revision as of 22:21, 1 June 2020
Line 7:		Line 7:

	While I was in the neighbourhood, I replaced the divider companion R220 with a new 2-watt 3k3 resistor.		While I was in the neighbourhood, I replaced the divider companion R220 with a new 2-watt 3k3 resistor.

			Of note: both R218 and R220 are 5% metal film. They're targetted at the automotive sector, and come with appropriate credentials, a flame-retardant coating, and safety qualifications.

Gordonp: Created page with "Bent, bruised and shorted R218 On the underside of the Relay Shelf, R218 can be seen shorting to the ground-lug. In..."

2020-06-01T22:17:54Z

Created page with "500px|thumb|center|Bent, bruised and shorted R218 On the underside of the Relay Shelf, R218 can be seen shorting to the ground-lug. In..."

New page

[[File:bent_bruised_shorted_r218.jpg|500px|thumb|center|Bent, bruised and shorted R218]]
On the underside of the Relay Shelf, R218 can be seen shorting to the ground-lug. In addition, R218 has physical abuse / chipping / scraping and nearby wires look crispy.

R218 is part of the Bias adjusting circuit: In CW mode it does nothing, allowing the full negative-bias voltage to reach the 4CX1000A and operate Class C. In SSB mode, this R218 is included in a voltage-divider, dropping the voltage down to whatever is necessar for the 200mA plate-idle-current (Class AB1) - often this reduced negative bias for SSB is in the range -35V (my experience with "stock") to -55V (my experience "modified" but the "stock" experience reported by others).

I replaced R218 with a modern 2-watt resistor.

While I was in the neighbourhood, I replaced the divider companion R220 with a new 2-watt 3k3 resistor.