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Best way to reduce power on the KWM-2


Peter E
 

I am looking at connecting my KWM-2 to a Mosfet linear. While the linear will happily handle 100W input, our less than forward thinking regulators restrict us to 400W max. As the linear has about 10dB gain I need to reduce the output to about 40W. Is it possible to do this safely by using the load control or is there another way?

Cheers,
Peter - VK2AN


ernst.schroeder@...
 

Hi Peter,

you may have a look at CCA "The Signal" issue 79, Q3 of 2015, the one with the Mercedes "Unimog" truck on the cover. Downloadable from here: http://www.collinsradio.org/signal/
There you can find my experience with reducing the output power of a KWM-2 to 10 watts. May be helpful in your case.

All the best, stay healthy,
73 Ernst DJ7HS
https://www.qsl.net/dj7hs/


Bill Cotter, N4LG
 

Peter,

Search e-Bay "High Power Attenuator 50" and you will see a lot of devices that can protect your MOSFET amp as well as present good matching. Here is a sample for $79

https://www.ebay.com/itm/High-Power-100-Watt-RF-Attenuators-DC-3GHz-50Ohm-1db-3db-5db-6db-10db-30db-40db/163975117483?hash=item262dadbaab:g:a6kAAOSwrQpd6MhE

73 Bill N4LG

At 05:37 AM 12/16/2020, you wrote:
I am looking at connecting my KWM-2 to a Mosfet linear. While the linear will happily handle 100W input, our less than forward thinking regulators restrict us to 400W max. As the linear has about 10dB gain I need to reduce the output to about 40W. Is it possible to do this safely by using the load control or is there another way?

Cheers,
Peter - VK2AN


OldBlueBear-G4JHT-Dave
 

hi, That should work as long as you keep it dipped or you could try dropping the PA screen voltage a method used in HP Txs to control Anode (Plate) dissipation.

Best of luck and 73s,
OldBlueBear-G4JHT-Dave


JEAN-LUC F6HOY - CCAE#003
 


Hi Peter and all,

My experience around 30L1 and KWM2 about Power..
I have 3 KWM-2, one 32S-3, one PRC47, two 30L-1 and several modern transceivers.

1) The 30L1 like 70 to 80w input.
2) I disconect the ALC input on 30L1 because it is never the same with all my transceivers.

How i adjust the output from KWM2 ?
With a dumy load in the line i just decrease MIC-GAIN on LOCK-KEY until i read 70 to 80w  on a wat-meter. (In my case i use some 312B-4.)

With my SWAN line (600-T and 600-R) i do the same way.
With modern TX i do the same.... I switch in CW mode an i adjust OUPUT_power to read 70 to 80w.

That's all for me since several years.... and my 30L1 are in good health.










___________________________________________________________________________________________________________
73 from Jean-Luc F6HOY - CCAE member #003 - Join CCAE on www.ccae.info and www.ccaeitaly.com and www.ccaespain.com


Peter E
 

Hi Jean,

As I am only reducing the power to 40, your method will probably work. I will give it a try, however I looked up issue 79 of the Signal and I really like Ernst's circuit. The beauty of this is I can build this circuit into my linear with an ALC adjust knob on the front and use the linear with various other old transceivers that I have also.

I can feel another project coming on....
 

Cheers,
Peter - VK2AN