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-   -   Reducing IC28H power output (https://www.radiobanter.com/equipment/16199-reducing-ic28h-power-output.html)

Yvson May 17th 04 09:09 PM
Reducing IC28H power output
 
Hi all!
I would like to know the proceedings to reduce the maximum power
output of the ICOM IC28H transceiver. I know that it has two levels of
power output: 5W and 45W. I'd like to reduce the maximum power output
to 20W or 25W (22W would be the best!). Someone told me that this kind
of equipment has an internal adjustment for this kind of work.

Could anyone help me?

73,
PR7BOK

Roger Grady May 18th 04 05:39 AM
(Yvson) wrote:

Hi all!
I would like to know the proceedings to reduce the maximum power
output of the ICOM IC28H transceiver. I know that it has two levels of
power output: 5W and 45W. I'd like to reduce the maximum power output
to 20W or 25W (22W would be the best!). Someone told me that this kind
of equipment has an internal adjustment for this kind of work.

Could anyone help me?

The power output on High is set by R71. This pot is located on the
main circuit board and is the right hand one of a pair of pots at the
rear center to the right of the biggest shield enclosure. The left
hand pot of the pair is R72 and sets the Low power level. The main
board is under the top cover. I have no idea what the range of
adjustment is for either. Bear in mind that some solid state RF
amplifiers don't like to work very far from their design power level.
Excess heating and spurious emissions can result

The service manual says to adjust the High power first, then the Low
power.


Roger Grady
To reply by email, remove "qlfit." from address

Roger Grady May 18th 04 05:39 AM
(Yvson) wrote:

Hi all!
I would like to know the proceedings to reduce the maximum power
output of the ICOM IC28H transceiver. I know that it has two levels of
power output: 5W and 45W. I'd like to reduce the maximum power output
to 20W or 25W (22W would be the best!). Someone told me that this kind
of equipment has an internal adjustment for this kind of work.

Could anyone help me?

The power output on High is set by R71. This pot is located on the
main circuit board and is the right hand one of a pair of pots at the
rear center to the right of the biggest shield enclosure. The left
hand pot of the pair is R72 and sets the Low power level. The main
board is under the top cover. I have no idea what the range of
adjustment is for either. Bear in mind that some solid state RF
amplifiers don't like to work very far from their design power level.
Excess heating and spurious emissions can result

The service manual says to adjust the High power first, then the Low
power.


Roger Grady
To reply by email, remove "qlfit." from address

Yvson May 18th 04 08:30 PM
Dear Mr. Grady, thank you so much for the help!

VY 73 to everybody,

Yvson - PR7BOK

Yvson May 18th 04 08:30 PM
Dear Mr. Grady, thank you so much for the help!

VY 73 to everybody,

Yvson - PR7BOK


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