Re: [SPAM] Re: [BITX20] RD16HHF1 in the uBITX #ubitx

Lawrence Galea
 

Thanks
That seems to be better.
So all one would to even out the power is to change C93 and C94 and put a a 110pf across T11 primary.
Thanks
Lawrence

On Tue, Feb 20, 2018 at 3:46 AM, K9HZ <bill@...> wrote:

50 nF seems to be optimal… but it also needs the compensator across T11 primary of 110 pf…   Roughly 22 watts on all bands except 6 meters where the power is 13 watts.

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

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Big Signal Ranch – K9ZC

Staunton, Illinois

 

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email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Lawrence Galea
Sent: Monday, February 19, 2018 11:36 AM
To: BITX20@groups.io
Subject: Re: [SPAM] Re: [BITX20] RD16HHF1 in the uBITX #ubitx

 

Hi,

I just unpacked my μbitx to check what was supplied and no time yet to hook it up.

Just a thought on the output power drop.

Can you try simulating reducing C93 and C94 so that with the corresponding higher reactance at lower frequencies less drive will be available at lower frequencies.

A value could be found to more or less even out the drive across the frequency range since the gate capacitance higher reactance at lower frequencies will compensate for the increased capacitive reactance of C93 and C94 while on the higher frequencies the opposite will be true.

Regards

Lawrence

 

On Mon, Feb 19, 2018 at 4:35 PM, K9HZ <bill@...> wrote:

> I did find the following in my simulations though... if you change R85 from 100 to 470 ohms (pre-driver stage bias), change R261 and R262 from 100 to 1K ohm, run RV1 wide open (full drive) and then use a compensating capacitor (your 33pf at 14 MHz) across T11 primary with a 1:4 transformer:

> 6M - 48pf

> 10M - 110pf

> 20M - 320pf

> 40M - 680pf

> 80M - 1,500pf

> 160M - 4,700pf

> It shows at least 20 watts out on each band except for 6 meters... where it peaks at 12 watts.

 

 

 

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

 

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

 

Owner – Operator

Villa Grand Piton – J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

Like us on Facebook! facebook icon

 

 

email:  bill@...

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Gordon Gibby
Sent: Saturday, February 17, 2018 6:54 PM
To: BITX20@groups.io
Subject: Re: [BITX20] RD16HHF1 in the uBITX #ubitx

 

​Dr. Schmidt -- no way to put some feedback into the circuit in some manner to stabilize the gain?    1000 pf across the 22 ohm emitter resistors to have a 3db break at 7 MHz?

 

 


 


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