Date   
Re: uBitx v4 new socket

Jack, W8TEE
 

All:

I've fallen behind the curve while I was away. Is there a bullet list somewhere that tells the difference between V3 and V4 of the board?

Jack, W8TEE

On Saturday, September 15, 2018, 9:41:24 AM EDT, Daniel <gonewiththeego@...> wrote:


Thank you very much for your support, Curt. I will try these days to start the board. Indeed, it's absolutely looking awesome. 

Re: uBitx v4 new socket

YO8UFO
 

Thank you very much for your support, Curt. I will try these days to start the board. Indeed, it's absolutely looking awesome. 

Re: uBitx v4 new socket

Curt
 

Daniel

very fine on the uBITX landing there.  my guess is that those connectors are to connect an add-on CW filter at the 12 MHz IF.  they are there for convenience - and not sure they have been widely used.  enjoy the small mysteries on the board that are intended to be there. 

given the nature of automated solder reflow, I think you are seeing it may not fill the holes.  these are likely conductive via connections between the two sides of the board, which your DVM has confirmed.  so that solder only needs to contact one side.  wow a nice looking circuit board - enjoy the RF using it. 

Curt WB8YYY

Re: Searching for IMD

Warren Allgyer <allgyer@...>
 

I have tested the MMIC based wideband amplifier board from SV1AFN ( https://www.sv1afn.com/wideband-mini-amplifier.html ) as a replacement for the 45 MHz transmit amp comprised of Q20 - Q22. I removed C20 and C22 and used two short lengths of miniature coax to take the signal off board to a 7 dB attenuator and then the amplifier, then back onto the board. Resulting MMIC amplifier gain was +16 dB.

The yellow trace is before the amplifier board was inserted and the purple trace after. 3rd order IMD was reduced by nearly 10 dB using the MMIC amp.

WA8TOD

Re: bitx40 on 80

Timothy Fidler
 

Argh.. if I get one and want to make it 40/20 then I will be the guinea pig.... Never mind.

you could of course have gone  for a Mkars 80 in that case which is still a good rig and I think still made as a kit down from the gorse and tartin  in the home counties of the English Dogs .  It uses a huff and puff VFO stabiliser controlled by a PIC micro.

However you have to scratch build it and it costs slightly more however it is all through hole so it is easier to hack about.  Digital display of course.

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:
Sat, 15 Sep 2018 05:48:32 -0700
Subject:
Re: [BITX20] bitx40 on 80


hi timothy

i am planning to make it mono band on 80 so no diode switch need thanks for info

i am in scotland

terry gm4dso

Re: bitx40 on 80

terry hughes
 

hi timothy

i am planning to make it mono band on 80 so no diode switch need thanks for info

i am in scotland

terry gm4dso

Re: bitx40 on 80

terry hughes
 

hi allard

i have changed lines 36, 37 and 47 as suggested but the scan still goes from 7.0 to 7.3
using the f button does not seem to work i also added my callsign

i confirm that 1.28.1 has loaded because my callsign appears on the display and 1.28.1 appears on start up

terry gm4dso

Re: Searching for IMD

Glenn
 

Henning, I am totally aware of the differences between the two Bi-Amps.  I built both versions on Vero for testing in this manner.  I confirmed his gain value within 0.5dB mid range.
You can see in my Plots the results of gain and response.

glenn


On Sat, Sep 15, 2018 at 05:02 PM, Henning Weddig wrote:

Glenn,

please compare the schematics of the Wes Hayward BiDI amp and Ashars version.

As Wes states his version is designed for 15 dB gain, resulting that he has a series feedback (680 ohms + cap) from collector to base. The biasing is done with two extra resistors.

Ashar uses only the biasing and feedback with the two resistors.

The result is that Ashars amp has about 20 dB gain, worse freqeuncy response (due to the limited ft of the 2N3904) and worse input reflection (S11). Due to the higher gain IMD must be worse at the same input level. If the textbook curve applies (3 dB for every 1 dB of input power change) the IMD will be 15 dB worse.

73

Henning Weddig

DK5LV

 

 

Am 15.09.2018 um 06:44 schrieb Glenn:

Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.







deleted this:-
On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn

Re: Searching for IMD

Glenn
 

Ashhar, I basically did this visually, using the Scope as a quick check between the two versions.

 I am aware of the Rule of Thumb about the IIP3 being 15-16dB above the 1db compression point.  

I will do a more accurate check using the SA tomorrow when i have more time available.

glenn


On Sat, Sep 15, 2018 at 04:05 PM, Ashhar Farhan wrote:
glen, you can do this,
 
find out, accurately, the gain of the amps at very low input levels.
Now, keep increasing the drive level until you see the gain dip by 1 db.
that is the compression point. For bipolar device amplifiers, the IIP3 will be about 15 above that point.
 
- f

On Sat, Sep 15, 2018 at 10:14 AM, Glenn <glennp@...> wrote:
Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.







deleted this:-
On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn

 

 

Re: Searching for IMD

Gordon Gibby <ggibby@...>
 

Thanks, Henning !


On Sep 15, 2018, at 03:03, Henning Weddig via Groups.Io <hweddig@...> wrote:

Glenn,

please compare the schematics of the Wes Hayward BiDI amp and Ashars version.

As Wes states his version is designed for 15 dB gain, resulting that he has a series feedback (680 ohms + cap) from collector to base. The biasing is done with two extra resistors.

Ashar uses only the biasing and feedback with the two resistors.

The result is that Ashars amp has about 20 dB gain, worse freqeuncy response (due to the limited ft of the 2N3904) and worse input reflection (S11). Due to the higher gain IMD must be worse at the same input level. If the textbook curve applies (3 dB for every 1 dB of input power change) the IMD will be 15 dB worse.

73

Henning Weddig

DK5LV



Am 15.09.2018 um 06:44 schrieb Glenn:

Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.

<uBITX_Bi_Amp_150910.jpg>

<HAYWARD_Bi_Amp_150910.jpg>



deleted this:-
On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn
<BiDi ubitx plot.pdf>
<BiDi ubitx schema.pdf>
<w7zoi original schema.pdf>
<w7zoi original plot.pdf>

Re: raduino connections on bitx40

terry hughes
 

hi
thanks for help - all working now

terry gm4dso

Re: Searching for IMD

Henning Weddig
 

Glenn,

please compare the schematics of the Wes Hayward BiDI amp and Ashars version.

As Wes states his version is designed for 15 dB gain, resulting that he has a series feedback (680 ohms + cap) from collector to base. The biasing is done with two extra resistors.

Ashar uses only the biasing and feedback with the two resistors.

The result is that Ashars amp has about 20 dB gain, worse freqeuncy response (due to the limited ft of the 2N3904) and worse input reflection (S11). Due to the higher gain IMD must be worse at the same input level. If the textbook curve applies (3 dB for every 1 dB of input power change) the IMD will be 15 dB worse.

73

Henning Weddig

DK5LV



Am 15.09.2018 um 06:44 schrieb Glenn:

Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.







deleted this:-
On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn

Re: Searching for IMD

Ashhar Farhan
 

glen, you can do this,

find out, accurately, the gain of the amps at very low input levels.
Now, keep increasing the drive level until you see the gain dip by 1 db.
that is the compression point. For bipolar device amplifiers, the IIP3 will be about 15 above that point.

- f

On Sat, Sep 15, 2018 at 10:14 AM, Glenn <glennp@...> wrote:
Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.







deleted this:-
On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn


Re: Searching for IMD

Glenn
 

Post 59439 is partly incorrect.  Just after I posted mentioning the visible clipping I realised, stupid me, was measuring gain during clipping which of course compresses the result.

I deleted that post. And have attached the new plots where you can see the  gain difference between uBITX and Hayward version. This obviously partly accounts for the difference in input levels before output clipping occurs. The biasing arrangement gives different Iq also.  Gain is reduced about  4dB in the Hayward version I built over uBITX. It now accords more closely also with  his test results of 15.5dB I get 16dB at 30MHz.

Haywards paper gives some values for varying the gain to other values also.







deleted this:-

On Sat, Sep 15, 2018 at 12:16 PM, Glenn wrote:
Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn

Re: Which xmit transistor is blown?

Sean W7SKD
 

Excellent point (cw key). One of those situations where you go down a road and don’t think to step back and rethink things. I convinced myself that it was a transmit issue related to amplification and didn’t challenge tha notion. 

Re: 2N2222A vs 2N3904 sourcing

ajparent1/kb1gmx
 

Hi Jim,...High gain in small pieces with input close to output...around and around it goes,,,

12:05 today I said...
So I know its doable, but you can not fold the amp on itself and have antennas (heatsinks) with RF and hope for stability.

Lumps of gain can be stable strung together in a cramped pace is much more of a challenge.  

I have amps that work very well.  Hans has done it as well.  All of the have one thing in common the
input is as far as possible from the output. Its not magic but trying to wring out the last drop of gain
is an unsuccessful way to go as its not stable even with good layout.  The next batch may or many
not work due to nominal variations.

Allison

Re: Searching for IMD

ajparent1/kb1gmx
 

Farhan,

>>>crucial thing is bias current and feedback. The biasing method itself is irrelevant.<<<

Generally yes but its easier to have the bias independent of the feedback as one forces
possibly less optimum values.

The other is that only the gain needed is employed not a case of what the circuit can do.

Allison

Re: Searching for IMD

Glenn
 

Hi Ashhur,
I just built up a proto of both versions on vero board.

As a rough check of IP3, since I am not set up to do proper measurement of IP3, I found that the 'visible distortion' of the Hayward version occurs about 10dB higher than the uBITX version.  ie the point of clipping (negative side in this case)  
~-22dBm for uBITX
~ -13dBm for Hayward.   This would then imply IMD is better.

In my set-up I found gain to be similar and pretty flat. I used junk-box parts of mixed tolerances. I built only one side of the Bi-Amps.
uBITX:-   ~ 12dB gain, flat over the range 3-45MHz flat within 0.8dB
Hayward:- ~ 10db gain, flat over same range within 0.6db

glenn

Re: 2N2222A vs 2N3904 sourcing

jim
 

Like most devices intended to oscillate, output getting back into input ...High gain in small pieces with input close to output...around and around it goes

Jim


On Friday, September 14, 2018, 12:32:38 PM PDT, ajparent1/KB1GMX <kb1gmx@...> wrote:


Allison, why would the MMICs oscillate and not a 2N2219A? Might screening of the mmic help?

Iz oos,

Simple the board layout is not suitable.  Screening is not effective.

Allison

Re: 2N2222A vs 2N3904 sourcing

Timothy Fidler
 

Re the bitch about RF power transistors from PRC being substandard or fake . If they are popular old CB radio PA transistors and are cheap they will most likely be fake .  " Cecil the parts place " in the US has a few RF or pushed into RF service transistors and mosfets. Most are from Fairchild  mafr ..  one hopes the real Fairchild.  Some have rather nice specs and he has links to small amps built with them.

NO I am not his brother  or a schiller for him as the Yanks say. Just noticed the site which is linked to a Steve Webber  design site.