Date   
Re: UBITX V3 TX GAIN VARIATIONS

MadRadioModder
 

Actually I’ve been doing a lot of experimentation on flattening/ linearizing the transmit chain.  The parts I’ve fallen on are the NE46134’s.  They have plenty of gain, Ft of 5 GHz, and with the proper inter stage transformer design… An almost flat (-0/+0.6 dB) frequency profile swept from 0.5-60 MHz is possible.  I suppose prototyped, it isn’t much of a uBITx though.

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of Kees T
Sent: Thursday, August 30, 2018 10:46 AM
To: BITX20@groups.io
Subject: Re: [BITX20] UBITX V3 TX GAIN VARIATIONS

 

On Tue, Aug 28, 2018 at 04:25 PM, Rod Davis wrote:

WARNING: q911,q912,q92,q93,q96,q97 all dissipate at least 296 mW. That
means 250 mW transistors are not acceptable.

So, in searching for a better Ft device for the TX chain:
the BFR106 has the dissipation, but the 3.5 to 5GHz Ft invites instability
the MMBT10     lists dissipation at 225 mW, so it may not be a good candidate
the MMBT2369 lists dissipation at 225 mW, so it may not be a good candidate
the DTX2222A has the dissipation, but the Ft is not better than 2n3904, and
the footprint is not compatible with the board.

I was wondering about the reasoning behind using several parallel 2N3904 transistors in the uBITX circuit.....they are inexpensive, but why not just use a single 2N2222 ?

73 Kees K5BCQ


Virus-free. www.avg.com

--

…_. _._

VK4PP uBitx LPF BANK add-on Board

Nick VK4PP
 

Hi All.
Hows this look:


73 Nick VK4PP

Re: UBITX V3 TX GAIN VARIATIONS

jim
 


On Thursday, August 30, 2018, 7:46:10 PM PDT, ajparent1/KB1GMX <kb1gmx@...> wrote:


On Thu, Aug 30, 2018 at 02:56 PM, Kees T wrote:
All of the WA2EBY derived dual MOSFET Amp designs I've seen (IRF510, RD16HHF1, RD15HHF1) have a "compensation capacitor" across the output transformer primary.  Used to balance the 3-30MHz range gain. I used one on my 20W Amp kit (and the feedback loop if needed).

Just finished (phase 1) of modifying to the WA2EBY topology ....Success is assured ...removes a metric B**t-ton of spurs and cruft ..Only getting 1 watt at 80 meters (100 mW on 10) but things are looking MUCH better

Jim

Re: UBITX V3 TX GAIN VARIATIONS

ajparent1/kb1gmx
 

Those points need series inductive(lossy ferrite) and/or resitive isolation as the
caps have ESR and however low if you present RF from the power supply side
its not sufficiently effective.

Of course if the ground via adds resitance it may not help.

Allison

Re: UBITX V3 TX GAIN VARIATIONS

ajparent1/kb1gmx
 

On Thu, Aug 30, 2018 at 02:56 PM, Kees T wrote:
All of the WA2EBY derived dual MOSFET Amp designs I've seen (IRF510, RD16HHF1, RD15HHF1) have a "compensation capacitor" across the output transformer primary.  Used to balance the 3-30MHz range gain. I used one on my 20W Amp kit (and the feedback loop if needed).

I'm familiar with your 20W amp.  Nice work.

The uBITX PA does not have such a capacitor on the schematic .....why ?

Actually the cap does several things but it may or maynot be there.  Most cases its to 
counteract remnant or leakage reactance from the transformer that occurs due to leads
and also coupling less that 1.   

In the case of the uBitx the existing transformer is well coupled but has far to much
inductance and any capacitance tended to make it worse at higher frequencies.
the winding is also high resistance.  Add to that the leas are long (full length) and
there are long and many tracks due to layout that are built of narrow traces. With
the circulating currents of @a or more would you use traces that narrow?

The feedback is not RLC but RC and should be RLC to compensate for the reactive
input of all mosfets.

That said if you delivered at least 500mW of power to the gates you get 10W out.
The drivers however do not deliver this above 9-10mhz.  So you get deceasing
output to 10M.  For mine at 10M it was 1.8W out but the drive was a mere .075mW.
Yet we blame the IRF510, looks to me 13db or more gain is not so bad.

The cap does not need to be a 500V part even at 28V as the mosfets will self destruct
at 100V, so a 100V cap is fine so long as it can handle high RF current.

Allison

Re: Raduino Pill

W3JDR
 

Today I got the Si5351 running, so all the subsystems (LCD, encoder, Si5351) are now operational. Next step is to try to build stock uBitX code on the new platform.

Re: Personal Best Distance, SSB Phone #ubitx

Ken
 

Nice one Joel!

73 Ken
VA3ABN

On Thu, Aug 30, 2018 at 6:26 PM, Joel Caulkins <caulktel@...> wrote:
I worked a station in Antartica from my QTH in Oregon, a distance of 10,455 miles, on a Bitx17A running 8 watts into a EFHW antenna. I have the QSL card to prove it!

Joel
N6ALT


Re: Personal Best Distance, SSB Phone #ubitx

Timothy Fidler
 

JC  Keep that Bitx17A .. it seems there will not be many more kits made.

BTW if you can get the 9 turn fine tuning air variable  out of an old UHF TV receiver ( typically can be made to tune 3-30pf  and less over the full 9 turns by cutting comps out and wiring the plates in parallel) you may be able to produce a non thermally moving VFO for that beast.  Australia killed off the Analogue network a while back and I had the opp. to examine the internals of some of these. 

 

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885, 
Telephone Whangarei   022  691 8405
e: Engstr@...



----- Original Message -----
From:
BITX20@groups.io

To:
<BITX20@groups.io>
Cc:

Sent:
Thu, 30 Aug 2018 15:26:36 -0700
Subject:
Re: [BITX20] Personal Best Distance, SSB Phone #ubitx


I worked a station in Antartica from my QTH in Oregon, a distance of 10,455 miles, on a Bitx17A running 8 watts into a EFHW antenna. I have the QSL card to prove it!

Joel
N6ALT

Re: UBITX V3 TX GAIN VARIATIONS

Kees T
 

......and the "compensation capacitor", since it's across RF voltages, should be a 500V Mica in the 47pF to 150pF range.

73 Kees K5BCQ 

Re: Personal Best Distance, SSB Phone #ubitx

 

I worked a station in Antartica from my QTH in Oregon, a distance of 10,455 miles, on a Bitx17A running 8 watts into a EFHW antenna. I have the QSL card to prove it!

Joel
N6ALT

Re: calibration question #ubitx-help

Mike KK7ER
 

Thanks, Iz Oos!  Just to be sure I'm not missing something subtle, why not just use WWV?  It is AM, isn't it?  And I know for sure that it is on 10.000000 MHz which is more than I can say for AM shortwave broadcasts chosen at random.

--Mike

Re: UBITX V3 TX GAIN VARIATIONS

Kees T
 

.....and I would still parallel a 1nF-10nF capacitor across the existing 100nF DC bypass capacitors....including the 2 MOSFET bias voltage bypass capacitors.

73 Kees K5BCQ

Re: Nextion 3.2 for CEC 1.097 #ubitx

SV9CVJ Nikos
 

Thank you very much dear Art this is a great help for me .

Re: UBITX V3 TX GAIN VARIATIONS

Kees T
 

Allison,

All of the WA2EBY derived dual MOSFET Amp designs I've seen (IRF510, RD16HHF1, RD15HHF1) have a "compensation capacitor" across the output transformer primary.  Used to balance the 3-30MHz range gain. I used one on my 20W Amp kit (and the feedback loop if needed).

The uBITX PA does not have such a capacitor on the schematic .....why ?

73 Kees K5BCQ

Re: Personal Best Distance, SSB Phone #ubitx

George Wulf
 

Can anyone send me a pic of uBITX manager with the loaded information for a ver 3. The uBITX is loaded with 1.097 and the display is loaded. I’m unfamiliar with the information process. I have learned so much on this project and want to continue to do so. I read everything that is posted here. It is truly a learning experience. 73’s KN4LPH

Re: BITX40 Saving Settings Issue

Allard PE1NWL
 


Double-check the PTT-sense wiring and resistor value (10K).
Also check the ground connections of the BitX40 main board and the Raduino.
General rule: All ground wires shall be connected to ONE central ground point ("star" configuration). There should be NO ground loops.

73 Allard PE1NWL

Re: BITX40 Saving Settings Issue

Allard PE1NWL
 

Hi Gary,

Perhaps there is a problem with your PTT_sense line.
The CW options in the SETTINGS menu are only available when the PTT_sense mod is installed.
Double-check the PTT-sense wiring and resistor value (10K).

Background:
When you power on, the software first checks whether or not the PTT_sense mod is installed. It does this by testing the logic level on the PTT_sense input.
If the mod is installed, the PTT_sense line will be LOW. If it is NOT installed, the PTT_sense line will be HIGH.

73 Allard PE1NWL

Re: calibration question #ubitx-help

iz oos
 

It seems out of calibration. To be sure follow the hint of using AM broadcasts on shortwave. They are exactly on the frequency they are supposed to be. You can use either LSB or USB and tune exactly to the point where you 'zerobeat' the carrier, so you don't hear the carrier of the AM broadcast and the audio sounds good. Read that frequency, eg. If you read for instance 15248.5 instead of 15250 you may want to calibrate. My uBitx was only 150hz and I left that like this.


Il 30/ago/2018 18:44, "Mike KK7ER" <groupio@...> ha scritto:
Two questions:

When I tune in 10MHz WWV in LSB mode on the uBITX, the frequency reads 9.998.500.  Does it mean the rig is out of calibration or is it supposed to read like this in LSB mode?  I note that Fc-BW/2 is exactly what I'm reading on the display so it makes me suspicious.  Before I go through the calibration procedure and potentially screw things up further, I was hoping someone can confirm.

BTW, the calibration procedure on hfsignals.com just says find an AM broadcast signal and says nothing about the mode the rig is set to (USB/LSB).  Doesn't the mode matter during calibration?  Thanks!

73 Mike KK7ER

Re: Nextion 3.2 for CEC 1.097 #ubitx

Art Olson
 

John, Nikos

 

Worked on page px 11 and 0  – not everything is correct but is about 90 percent. ATT and IFS don’t function correctly yet. Could be some others. I will stopped for today. Nikos I guess you have control until I hear back from you. Give it a try

 

Art – N2AJO

 

 

From: BITX20@groups.io [mailto:BITX20@groups.io] On Behalf Of SV9CVJ Nikos
Sent: Thursday, August 30, 2018 9:53 AM
To: BITX20@groups.io
Subject: Re: [BITX20] Nextion 3.2 for CEC 1.097 #ubitx

 

HI John

I've done all the resizing except page 11 and 0 px which is a little complicated for me .

Nikos SV9CVJ


Virus-free. www.avg.com

Re: Any Gerber Experts Round Here? #kicad #ubitx

Jerry Gaffke
 

Garbage in, garbage out.
And when fabbing PC boards, you really don't want garbage.
This world has way to many coffee mug coasters already. .

A local software tool such as Gerbv or GerbView will allow you to preview the files and see what's wrong.

You might also look over OshPark, they have a great front end for ordering boards.
    https://docs.oshpark.com/submitting-orders/preorder-checklist/
They give a good rendering of exactly what the board will look like before you enter your credit card number and pull the trigger.
If you can get it to where the board passes their checks and looks right, you have a good chance of getting back a usable board.

Jerry


On Thu, Aug 30, 2018 at 11:45 AM, Ben Holmes wrote:
You might find this amusing, but I already did this... and Fiverr responded with the following:

Unfortunately, your Gig request "Gerber Files... Convert RS-274D to..." did not pass our review.

It was misleading or unclear. Please explain, in a clear way, what service you need.

Repeating these violations can result in your account being restricted.