----- Original Message -----

From: Scott Tilley

To: [email protected]

Sent: Thursday, September 29, 2011 6:27 PM

Subject: Re: LF: Wilkinson combiner

Thanks Mal

Hope you have success with this. 

If reliability is key, consider using a three or four port version.  I use a 4 port version in my MOALFA amp.  With more smaller amps you don't need to push each individual amp as hard which is nice during fault conditions or stormy weather.  Never lost a FET on this amp.  Well to be truthful, I killed them all during the first test setup when I melted my dummy load that had a faulty connection on the water cooling...

I just noted Jim's comments and I agree with him about the efficiency statement.  My main motivation for creating my high power amp was the lack of efficiency in my TX antenna system (poor vertical or big loop).  The final compromise was a big amp and a loop.

The smaller multiple stages allows the use of less exotic ferrite materials (I use TV flyback cores) and cheaper transistors etc etc etc...

My amp has two settings:
Stun (1KW) and KILL (2KW)

:-)

Scott



 

On 9/29/2011 10:49 AM, mal hamilton wrote:

Scott

A nice neat job, tidy build

.

 

mal

 

----- Original Message -----

From: Scott Tilley

To: [email protected]

Sent: Thursday, September 29, 2011 4:30 PM

Subject: Re: LF: Wilkinson combiner

Hi Mal

This was the original 2 port design I used to combine two 500W amps.  Works fine.  Steve, VE7SL uses this design done as well for his 1KW amp.

http://www3.telus.net/sthed/argo/wilk/

A possible benefit is that the combiner elements provide very good low pass filtering so you may not need a separate filter.   Make sure the LO chain of both amps is shared.

This design should be fine for your application and won't need ferrite.

73 Scott
VE7TIL



On 9/29/2011 8:34 AM, mal hamilton wrote:

Components would need to be hefty to handle two amps each one several hundred watts to get 1w erp on 137

Maybe the decca approach is better with just a transformer, 3 primary winding and one output winding, their method handles 1.2 K/watts without any strain.

g3kev

 

----- Original Message -----

From: mal hamilton

To: [email protected]

Sent: Thursday, September 29, 2011 8:46 AM

Subject: Re: LF: Wilkinson combiner

Scott

Two amplifiers to combine to one output. 2 ports in 1 port out

de mal/g3kev

 

----- Original Message -----

From: Scott Tilley

To: [email protected]

Sent: Wednesday, September 28, 2011 10:17 PM

Subject: Re: LF: Wilkinson combiner

Hi Mal

How many ports?

I personally prefer air core coils but iron dust work better than ferrite for this application.  Amidon #3 is the best.

Once I know the number of ports I can give you values.

Regards,
Scott


On 9/28/2011 10:59 AM, mal hamilton wrote:

LF/MF    Is anyone using a wilkinson combiner with LF amplifiers and if so what are the optimum paramaters for ferrite cores/windings

73 de mal/g3kev