Re: boosting the power on 28 MHz #ubitx

Tim Gorman
 

Bill

Thanks. Sounds like something I might want to try next time I have the
mainboard out of the case.

tim ab0wr

On Sat, 12 May 2018 21:58:57 -0500
"K9HZ" <@Doc_Bill> wrote:

Yes it does increase the output across the entire spectrum, but
mostly above 18 MHz, and it is greatest at 28 MHz . It cancels some
inductance at higher frequencies that is problematic. I see a
maximum of 26 watts on 40 meters and 19 watts on 10 meters... you can
easily dial that back with RV1 accordingly.


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

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

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Soufriere, St. Lucia W.I.
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email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim
Gorman Sent: Saturday, May 12, 2018 6:59 PM
To: BITX20@groups.io
Subject: Re: [BITX20] boosting the power on 28 MHz #ubitx

Does the cap provide output leveling or increased output from 80m to
10m?

I mainly operate 80m, 40m, and a little 20m. The output there seems
to be fine for what I do.

tim ab0wr

On Sat, 12 May 2018 16:56:57 -0500
"K9HZ" <@Doc_Bill> wrote:

I just put mine at the base of T11 but there are many ways of doing
it depending the type of part you use... I also replaced T11 but
let's not go there yet.


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!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Tim
Gorman Sent: Saturday, May 12, 2018 4:31 PM
To: BITX20@groups.io
Subject: Re: [BITX20] boosting the power on 28 MHz #ubitx

How do you recommend doing that? A disc ceramic between IRF510 pins?
Can you get an smd cap between the pins on the bottom of the ckt
board?

tim ab0wr

On Sat, 12 May 2018 13:38:52 -0500
"K9HZ" <@Doc_Bill> wrote:

Did you try putting about 330pf across the primary of T11 (PA
output transformer). That will make a big difference...


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!

Moderator – North American QRO Group at Groups.IO.

email: @Doc_Bill



-----Original Message-----
From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of
Skip Davis via Groups.Io Sent: Saturday, May 12, 2018 1:27 PM
To: BITX20@groups.io
Subject: Re: [BITX20] boosting the power on 28 MHz #ubitx

Allison I tried the 220pf cap on RV1 and didn’t see any gain at
28 MHZ. I also tried removing the feedback resistors in the
finals suggested by Farhan without any gain. What I also have
done was the capacitor/choke mod suggested by Howard for the
driver stages and that has worked. With RV1 set to 10 watts on 40
meters I now get about 2.5 watts on 28 MHZ up from the 1.25 - 1.5
watts before. I also see about 8 or 9 watts on 20 meters. I’m
running Ian’s firmware I think version 1.06 something.

Skip Davis, NC9O




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