Dummy load - Revision history

Carlb: /* Where can I buy a dummy load? */

2009-04-09T01:23:57Z

Where can I buy a dummy load?

← Older revision		Revision as of 18:23, 8 April 2009
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	==Where can I buy a dummy load?==		==Where can I buy a dummy load?==
			* [http://www.rfparts.com/dummy.html RF parts]

	~~[http://www.rfparts.com/dummy.html RF parts]~~
			{{electronics}}

TimVK4YEH: fixed omega

2008-08-24T08:06:44Z

fixed omega

← Older revision		Revision as of 01:06, 24 August 2008
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	==Where can I buy non-inductive resistors from?==		==Where can I buy non-inductive resistors from?==

	Look for metal film or metal oxide resistors. For example, twenty 1K<math>/Omega</math> resistors - each rated at 3W or more - mounted in parallel will provide an almost purely resistive load capable of handling 100W+ from a transceiver.		Look for metal film or metal oxide resistors. For example, twenty 1K<math>\Omega</math> resistors - each rated at 3W or more - mounted in parallel will provide an almost purely resistive load capable of handling 100W+ from a transceiver.

	==Where can I buy a dummy load?==		==Where can I buy a dummy load?==

	[http://www.rfparts.com/dummy.html RF parts]		[http://www.rfparts.com/dummy.html RF parts]

TimVK4YEH at 07:52, 24 August 2008

2008-08-24T07:52:43Z

← Older revision		Revision as of 00:52, 24 August 2008
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	* normally have a resistance of either 50<math>\Omega</math> or 75<math>\Omega </math>		* normally have a resistance of either 50<math>\Omega</math> or 75<math>\Omega </math>

	==Are there different sorts of dummy load?		==Are there different sorts of dummy load?==

	In a word, yes. Dummy loads are known as either:		In a word, yes. Dummy loads are known as either:
Line 28:		Line 28:
	* dry - the resistance will generally be integral to a heatsink, often cylindrical in shape		* dry - the resistance will generally be integral to a heatsink, often cylindrical in shape

	==~~can~~ I make my own?		==Can I make my own?==

	Yes. Non-inductive resistors are required so that the dummy load is as close as possible to being resistive only.		Yes. Non-inductive resistors are required so that the dummy load is as close as possible to being resistive only.

	==Where can I buy non-inductive resistors from?		==Where can I buy non-inductive resistors from?==

	Look for metal film or metal oxide resistors. For example, twenty 1K<math>/Omega</math> resistors - each rated at 3W or more - mounted in parallel will provide an almost purely resistive load capable of handling 100W+ from a transceiver.		Look for metal film or metal oxide resistors. For example, twenty 1K<math>/Omega</math> resistors - each rated at 3W or more - mounted in parallel will provide an almost purely resistive load capable of handling 100W+ from a transceiver.

TimVK4YEH: added info and links

2008-08-24T07:51:53Z

added info and links

New page

Related wiki pages: [[Antennas]], [[SWR]]

==Why use a dummy load?==
A Dummy Load is used instead of an antenna when a transceiver is tested or adjusted. Reasons for using a dummy load include:

* using a transceiver without a load - either an antenna or a dummy load can seriously damage it

* a transceiver will exhibit different transmitting characteristics with a load, compared to transmitting without one. This can lead to incorrect adjustments being made to the transceiver circuits

* transmitting into a dummy load with a badly aligned transceiver does not cause [[Interference |interference]]

==What are the characteristics of a good dummy load?==

The ideal dummy load will:

* be purely resistive, with a [[Resistance |resistance]] equal to the [[Impedance |impedance]] of the [[Feedline |feedline]] or [[Antennas |antenna]] that the transceiver will normally be used with.

* be designed and constructed to absorb the amount of power that the transceiver delivers

* normally have a resistance of either 50<math>\Omega</math> or 75<math>\Omega </math>

==Are there different sorts of dummy load?

In a word, yes. Dummy loads are known as either:

* wet - the resistance is immersed in mineral oil to dissipate heat or

* dry - the resistance will generally be integral to a heatsink, often cylindrical in shape

==can I make my own?

Yes. Non-inductive resistors are required so that the dummy load is as close as possible to being resistive only.

==Where can I buy non-inductive resistors from?

Look for metal film or metal oxide resistors. For example, twenty 1K<math>/Omega</math> resistors - each rated at 3W or more - mounted in parallel will provide an almost purely resistive load capable of handling 100W+ from a transceiver.

==Where can I buy a dummy load?==

[http://www.rfparts.com/dummy.html RF parts]