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Drake L75 output


 

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Okay, with all this chatting about RF output for the L7

what should I see into a 50¦¸ load from my L75? It had but one 3-500Z.

Mike wb8vge



On Mar 5, 2024, at 10:01 AM, Steve Wedge, W1ES/4 via <w1es@...> wrote:

Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.

Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.


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I'd say at least 600W.? In practise, it could be more because the power supply is likely a little "beefier" in proportion.

Steve Wedge, W1ES/4

Time flies like an arrow.? Fruit flies like a banana.

Sent with secure email.

On Tuesday, March 5th, 2024 at 10:54 AM, mike bryce <prosolar@...> wrote:

Okay, with all this chatting about RF output for the L7

what should I see into a 50¦¸ load from my L75? It had but one 3-500Z.

Mike wb8vge



On Mar 5, 2024, at 10:01 AM, Steve Wedge, W1ES/4 via <w1es@...> wrote:

Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.

Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.


Sent from for iOS





 

As I recall, the L75 had more than half the output of the L7. ?Even though the L75 only had one tube, it had a higher plate voltage than the L7 and thus the resulting power out.

73,

Evan, K9SQG

On Tuesday, March 5, 2024 at 10:54:59 AM EST, mike bryce <prosolar@...> wrote:


Okay, with all this chatting about RF output for the L7

what should I see into a 50¦¸ load from my L75? It had but one 3-500Z.

Mike wb8vge



On Mar 5, 2024, at 10:01 AM, Steve Wedge, W1ES/4 via <w1es@...> wrote:

Tim, the sole reason for the CW position, at the time of manufacture, was to keep within the power regulations that were in place, in the USA, at the time. ?The limitation was 1000 watts input power, which was obtained on CW by multiplying the plate voltage by the plate current. It was acceptable then to estimate the power input for SSB, since there was no easy way to measure PEP.

Having said all of that, I do consider the CW position to be useful for digital modes, as it limits the power out to a safe level for the amp. When I use the amp (rarely) for digital modes, I keep my output at around 500 - 600W. ?On CW, I use the amp on the ¡°SSB¡± position to get max power out, which is around 1200W if you keep the grid current within the tube ratings.

Steve Wedge, W1ES/4

Time flies like an arrow. Fruit flies like a banana.


Sent from for iOS




 

I Had to rebuild the power supply and get more than 800 watts output.
73s
Wolfgang
dk7cy