Re: 2N2222A vs 2N3904 sourcing
Parallels between uBITX and BITX40 TX chain:
I noticed in the BITX40 (the BITX40 schematic print is low resolution, so pardon if I get a part number wrong) that the uBITX Q90 corresponds to the BITX40 Q13, Q911-Q912 to Q14, and Q92-Q93-Q96-Q97 to Q15 (the final) on the BITX40.
At that final stage in the BITX40 it can put out 7 watts. Would there be any advantage in reworking the uBITX so that the stage with?Q92-Q93-Q96-Q97 was replaced with a IRF510 and the transformers and bias rewired to be like the BITX40 final? Then let that reworked stage drive the Push-Pull IRF510 PA stage of the uBITX.
Tom, wb6b
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Re: 2N2222A vs 2N3904 sourcing
Am 13.09.2018 um 22:18 schrieb Kees T: I think enough work has been done to say the 3 sets of 2N3904 transistors should be replaced with 3 sets of 2N2222A transistors. The 2N2222A is a great transistor but has been around a while and most retailers have classified them as "obsolete" and dumped the plastic versions to surplus dealers to sell. They still sell the TO-18 metal can versions at quite high prices because the military still needs them to repair "stuff". Many surplus dealers now have the plastic 2N2222A parts available for pennies on places like ebay. Have found some 2N222A (metal) in my junkbox. They are labeled as "COIL 2N222A" Hfe around 145 but also some with Hfe around 250. If I replace the 6 2N3904 in the PA driver stage by 2N222A how the PA will be improved by this change? Must the 2N222A be paired? Sorry, tried to find out the begin of the discussion but got stuck in the "where to buy" discussion. 73 Matthias, DD7NT
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As an aside, I tested this particular MMIC board for its susceptibility to oscillation. I connected a 60 dB attenuator between the input and output while I fed a signal to the input. I gradually reduced the attenuation one dB at a time until oscillation was visible on a 1.5 GHz spectrum. The amplifier broke into oscillation very reliably when the attenuation was stepped below -14 dB. Higher than that and it was completely stable.
In the course of these two tests the board was hanging unshielded about 3 inches from the PA heat sinks and the output was a little over 4 watts. In both cases I saw no indication of oscillation.
WA8TOD
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I restored the Q20 - Q22 amplifier and moved the MMIC amp to the Q40 - 42 amp with similar results. Here I required the full 23 dB of gain provided by the MMIC to achieve the same level of main signal. Yellow and purple traces are as before with the new measurement indicated on the blue trace. Results are almost identical indicating replacing these two amps together would provide 19 - 20 dB of IMD improvement which would make the transmitter completely viable and, in fact, better than some commercial radios in terms of IMD. In both cases the indicated power out from the two tone test was a little over 4 watts. WA8TOD 
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My list of Firmware, Executables and Nextion Screens for the ubitx
Thought this would be helpful for all the ubitx users.
My list of? various firmware and software for the ubitx.
Marty
N5KBP
?
?
Latest Dr. Ian Lee KD8CEC's firmware?
Raduino Source & Hex, MM EXE & HMI's for Nextion
https://github.com/phdlee/ubitx/releases/tag/1.1
?
Hex for I2C dspmeter
https://drive.google.com/file/d/1Oc-bGS34f0ragGXQ1lK6HHB7GhZLHZrP/view
?
Source for I2C dspmeter
https://github.com/phdlee/dspmeterv1
?
Rich Neese KB3VGW's Custom Nextion Screens from 2.4 to 7.0 inch. TFT's and HMI's
https://www.mediafire.com/folder/mmu6ua683lk93/Nextion-Screen-1097
?
BJ Pasteuning PD5DJ's 4.3 custom version. TFT only for 4.3 Nextion.
http://ubitx.net/2018/07/23/2831/
-- N5KBP
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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.?
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Thank you very much for your support, Curt. I will try these days to start the board. Indeed, it's absolutely looking awesome.?
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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
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I have tested the MMIC based wideband amplifier board from SV1AFN (??) 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
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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 -----
To: <[email protected]>
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
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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
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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
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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
toggle quoted message
Show quoted text
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
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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
toggle quoted message
Show quoted text
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
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Thanks, Henning !
On Sep 15, 2018, at 03:03, Henning Weddig via Groups.Io < hweddig@...> wrote:
toggle quoted message
Show quoted text
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
hi
thanks for help - all working now
terry gm4dso
|
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:
toggle quoted message
Show quoted text
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
|
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
|
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
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Re: Which xmit transistor is blown?
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.?
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YO8UFO
