Gents and ladies, I don't post much as I'm a busy broadcast engineer.? But I try to read often.
Allison's post contains wisdom.

Education tends to be expensive.? If your goal is IRF R&D, then knock yourselves out.? You will go through a lot of parts, and likely as not, spend a lot more time and money in acquiring the knowledge and experience.? In the end, you'll know what a part can or cannot do.? If that's YOUR goal, great.

For myself, my time is worth something to me.? I think it's false economy of both my time and money to blow up a few dozen $0.50 parts, chasing issues created by the selection of an inferior part from an unreliable source, when one appropriately selected and sourced $4.75 part will accomplish MY goal - to use a piece of equipment that I built.? The former is not worth the hassle.

If you need a cliche, here's two:? I'd like to "not reinvent the wheel," but would much rather "stand on the shoulders of giants."

Two cents duly submitted.

73,
Russ Hines
WB8ZCC
--
Reply to: russ@...

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Hi this an interesting read.
?
Cheers
Kevin
VK2KTG

Hi Jerry,

What do you mean by "Be very careful about setting those pots to "a lot more" than 100ma,?
that's a good way to make the IRF510's pop from the heat." What's? a lot more? I found I needed to adjust my bias to 150mA each just to get the PO to be on par with most others. By your formula above I would get? 12v*0.150A=1.8 watt. Am I correct??

Do you - or anyone here - have suggested maximum bias mA's? (BTW, I have a rather large computer cabinet fan that I salvaged and blow directly on the PAs.}

Thanks!
Dave, WS1ETI

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Hi Norm,

if you go to

about the 7th line down, click on manual.

Rod KM6SN

Sold! Thank you!

Hello,

In Europe, you can order to

but this is not the price of an IRF510 hi !

73’s Jacques –F1APY

On Sun, May 13, 2018 at 06:22 am, richcarter03052 wrote:

There are a number of threads that describe mods to the uBitx.? It's getting a bit tedious to hunt through threads to find tested and verified mods.? It would be nice if they were collected in one place.

There is such a place. ZL1AXG puts in about 23 hours a day at

It would be nice if there were a computer interface and cat software available.

look for KD8CEC on the link above



?
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I hooked up a calibrated signal source and verified that I can receive a 1uv signal on all bands.? This is consistent with performance of most modern rigs.? I find the rig a bit difficult to tune however, possibly due to an SSB filter that is too wide.

Rich - KE1EV

I built a fully featured Elecraft K2 a few years back.? It has a variable bandwidth crystal ladder filter.? I wonder if the uBitx filter can be adapted to vary it's bandwidth in a similar fashion, perhaps with an external pot rather than under processor control.

There are a number of threads that describe mods to the uBitx.? It's getting a bit tedious to hunt through threads to find tested and verified mods.? It would be nice if they were collected in one place.

Rig operation is awkward due to the lack of frontpanel controls.? It would be nice if there were a computer interface and cat software available.? The new enclosure provides an external board with serial and USB connectors, but no instructions on how to hook these up and what they can do.? If anyone figures this out, please respond.

Rich - KE1EV

If you aren't seeing any power drain and you are still in receive then
the first place to start is at K1. Check the voltage at the base of Q15
to see if it changes when you press the PTT. If it does then your K1
may not be operating correctly.

tim ab0wr

On Sun, 13 May 2018 02:35:10 -0700
César EA3IAV <Cesarleon@...> wrote:

Hi guys.
When I press ptt i see tx on the screen but sound does not turn off
and i see no power drain or power out on my meter wiring is fine on
the mic. Where woukd you start from to find the culprit? it seems
that components are crappy enough to have you fixing this piece of
all ... the rest of your life

I used the same NESCAF filter and am very happy with it.? I have not tried it on contest conditions yet but for casual operation it has given a big improvement.??

Mark
KC4GIA?

On 80m/40m/20m the ubitx receives as well as my FTDX3000. Those bands,
esp 80m/40m, are noise limited not sensitivity limited. The 3000, of
course, has more filter options which helps control received noise.
However, an audio filter with a peak mode significantly helps the
ubitx on cw.

On the higher bands a pre-amp might help. That can be added in the
receive path just like nd6t's agc circuit and can be switched in and
out at need.

tim ab0wr

On Sat, 12 May 2018 20:10:06 -0700
"Tom, wb6b" <wb6b@...> wrote:

I see a lot of good conversations here about improving the uBITX
transmitter output. However, I see very little about how good the
receiver is. My question is, have many people done comparisons of the
uBITX receiver vs their other radios; particularly on SSB?

?

In my case I have noticed that my SDR using a cheap dongle seems to
outperform the uBITX receiver substantially. Even though I don’t
consider the SDR dongles to be the pinnacle of RF design, I guess
throwing brute force real time math at the receiver side makes up for
some of it.

?

Are the uBITX receivers ripe for improvement?

?

In Europe MRF510 can be bought from Conrad electronics, brand Vishy, for 50 cent plus shipping.
Unfortunately they do not offer RD16.

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" <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

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: bill@...



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tim
Gorman Sent: Saturday, May 12, 2018 6:59 PM
To: [email protected]
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" <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: bill@...



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tim
Gorman Sent: Saturday, May 12, 2018 4:31 PM
To: [email protected]
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" <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: bill@...



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Skip Davis via Groups.Io Sent: Saturday, May 12, 2018 1:27 PM
To: [email protected]
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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