Re: 2N2222A vs 2N3904 sourcing
I've just had a look, and 2n222A are available readily enough at Cricklewood.?
|
Re: 2N2222A vs 2N3904 sourcing
On Fri, Sep 14, 2018 at 11:07 AM, Tom, wb6b wrote:
Assuming the MMC amps can work without the issues that are being pointed out, the idea of using an assembled amplifier board, for us retrofitters (like the assembled filter boards folks are creating) might make mods easer. Here is an amplifier I bought on Amazon. The Mini-Circuits amplifier looks like it has better spec for use in the TX chain. But, this board cost $10.99 (and I have it here). If only 10DBm output drive is usable, it has a little more gain (oscillation caveat noted). I saw similar boards for less money, elsewhere.?
I have? handful of those.? Handy but a lot of gain. The gain has conditional stability as well.
I've had them take off when using poo input or output match.? The part shown is MAR8SM+,
I'll attach a datasheet.? ?FYI they prefer regulated voltages.
?
There are better parts in the Gali and other series I have them too and protoboards like that one.
I do a lot of VHF and UHF stuff so I even have connectorized block amps with 20db of gain and?
26dbm (-1db) output.? Consider this replacieng Q90, pre-drivers, Drivers with 2n5109s or other
devices that can deliver the gain based on feedback values ends up with the whole mess
oscillating as now with enough gain the isolation due to layout fails.
Actually for several tried replacing the 3904s with BFR106 in the q90 slot and dialing down the bias.
Replacing the 3904s in teh pre-driver and driver and both cases change up the emitter resistors
to 11ohms or 8.2 and then rest idling bias to under 20ma with series RLC feedback rather than RC
was easily done good bang for the money and reproducable(,-- magical) and in most cases set
to about 12w at 80m (q90 emitter 70/680/820pf) cap mod it was around 4-5W at 10M.?
Good enough for reasonable effort.
Allison?
one pill wishful thinking.
|
Re: 2N2222A vs 2N3904 sourcing
On Fri, Sep 14, 2018 at 11:13 AM, Warren Allgyer wrote:
an see how that could happen if trying to fit the MMICs into the existing board layout. One critical thing has changed however: we have moved a PA filter section that was laid out extremely poorly and leaking like a sieve, off the board along with it's high power leakage. The MMICs in question are designed to be laid out on 50 ohm PCB transmission lines and, if done that way, are nearly impervious to external unwanted feedback. Fitting them into the existing board is a non-starter.... agreed. But, as an overlay card with properly laid out transmission line inputs and outputs, replacing each of the transmit bi-directional amps and the driver stages up to the -7 dBm level or so would have a dramatic effect on IMD and it is hard for me to accept they would not be far less prone to oscillation than existing components in the existing layout.
Warren,
I've used MMICs for many years.? Generally the design was built with them in mind and not as a bandaid.
The application for the ubitx was to make up for low gain IE: spool the stage gains down so 2222A or 2219
could be used at 11-12db gain with feedback and make up the need with a 10db MMIC.? ? Stability in a word
was poor.? I had the same issue trying devices that would make the same gain at 10M as 80m (5109s or 6661Vmos)
and the thing was unstable as well.? ? Last pass before I moved to bigger issues was make the IRF510s an offboard
output element using a board I had with seriously better layout and that did work with the 5109 drivers and gave
me less than 2db gain tilt. However it was again unstable when I tried to route the power back through the low pass
filter array as it was.? Spurs and carrier leak and the infamous low pass filter were bigger fish that required frying.
A project for my self is a resurrected a Atlas210x ( really old radio with DBMs for mixers) and I've built a requisite
60db 10W power amp for it with minimal difficulty that is flat (+-1db) to 30mhz using IRF510 PP.? Its all about layout.?
So I know its doable, but you can not fold the amp on itself and have antennas (heatsinks) with RF and hope for stability.
I assume you know that but its also for the audience.
Allison
|
|
|
Re: Which xmit transistor is blown?
Just to see whether it puts out the correct amount of power why not just keying down CW?
Il 14/set/2018 20:11, "Sean W7SKD" < sean.jrdalys@...> ha scritto: Ok, I think I have this solved.
Really short version:
It appears that my major problem was the laptop that I was using for FT-8.? The laptop that I have been using is not putting out consistent volume/drive on wsjt-x with ft8 (even with a different sound card).? A different computer was tried and everything now works fine.
Longer version:
Ok, I'm a bit at a loss for 'why' this has happened, but here's what happened.? I spent a LOT of time tracing the transmit signal, going back through the mixer stages and into the mic amp (q6).? What I started to notice was that everything looked just great at DC levels, but when under drive ('tune' signal from wsjt-x), the signal levels and frequencies didnt seem to make sense.? I connected a commercial hf transceiver up to the same PC (which I hadnt done, as I didnt have access to one) and discovered that it was doing the SAME thing - effectively no output.? ?I tried a different sound card (usb connected) with the same problem.? When I switched to a different PC with the commercial transceiver, TWO things were discovered:? 1) suddenly I had signal coming out and 2) the transceiver was warning me of high swr.
so...high swr.? It appears that my tuner was set up incorrectly (mfj-971 - has 2 internal jumpers that have to be set for qrp operation, and the swr movement was incorrectly set), and I was likely running high swr for quite a long time with my ubitx and not realizing it.?
Once I got the tuner situation dealt with, the commercial rig works great with the NEW laptop, and still does not work well with the old laptop.? The ubitx ALSO works well with the NEW laptop now.? Whats really odd is that the OLD pc's soundcard still works fine with earbuds, just not driving either radio.
so...what I'm left with appears to be an odd pc situation (inability to drive the radio, but no other noted malfunction), but functioning radio gear.? If anyone has ideas on that, I'm open to them, but I'm not going to expend much effort in that area.
THANK YOU to those who posted and emailed me things to check.? I got into radio in order to learn more about electronics, and that is absolutely happening
73
Sean
|
Re: 2N2222A vs 2N3904 sourcing
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
Mini Circuits have developed many MMICS with better imd specs than the MAV or the ERA. The many Gali and the Pga don't cost much more. Maybe it would be worth to test these for TX purposes.
Il 14/set/2018 20:07, "Tom, wb6b" < wb6b@...> ha scritto: Assuming the MMC amps can work without the issues that are being pointed out, the idea of using an assembled amplifier board, for us retrofitters (like the assembled filter boards folks are creating) might make mods easer. Here is an amplifier I bought on Amazon. The Mini-Circuits amplifier looks like it has better spec for use in the TX chain. But, this board cost $10.99 (and I have it here). If only 10DBm output drive is usable, it has a little more gain (oscillation caveat noted). I saw similar boards for less money, elsewhere.?
Would be interested in knowing if this LNA might be up to par for the TX chain.
I believe the board is using this LNA chip.?
Tom, wb6b
|
Re: 2N2222A vs 2N3904 sourcing
This is exactly the layout I am suggesting Tom. It is very difficult to make such an amplifier oscillate with external stimulation due to the transmission line layout and low component count.
One caution.... preliminary testing tells me the amp should not be put in a design at its rated output. IMD on the similar SV1AFN board measured better than -55 dBc at -7 dBm with zero compression. At 0 dBm and 1 dB of compression IMD had deterioriated to -30 dBc and at its rated +7 dBm output compression was nearly 2 dB and the consequent IMD was -23 dBc.?
If I were doing the design I would plan run them 10 dB below rated output. The gain is still there..... it is just not a very good PA!
WA8TOD
|
Re: 2N2222A vs 2N3904 sourcing
toggle quoted message
Show quoted text
Assuming the MMC amps can work without the issues that are being pointed out, the idea of using an assembled amplifier board, for us retrofitters (like the assembled filter boards folks are creating) might make mods easer. Here is an amplifier I bought
on Amazon. The Mini-Circuits amplifier looks like it has better spec for use in the TX chain. But, this board cost $10.99 (and I have it here). If only 10DBm output drive is usable, it has a little more gain (oscillation caveat noted). I saw similar boards
for less money, elsewhere.?
Would be interested in knowing if this LNA might be up to par for the TX chain.
I believe the board is using this LNA chip.?
Tom, wb6b
|
Re: 2N2222A vs 2N3904 sourcing
Allison
I can see how that could happen if trying to fit the MMICs into the existing board layout. One critical thing has changed however: we have moved a PA filter section that was laid out extremely poorly and leaking like a sieve, off the board along with it's high power leakage. The MMICs in question are designed to be laid out on 50 ohm PCB transmission lines and, if done that way, are nearly impervious to external unwanted feedback. Fitting them into the existing board is a non-starter.... agreed. But, as an overlay card with properly laid out transmission line inputs and outputs, replacing each of the transmit bi-directional amps and the driver stages up to the -7 dBm level or so would have a dramatic effect on IMD and it is hard for me to accept they would not be far less prone to oscillation than existing components in the existing layout.
In a prospective v5 radio the used of MMICs as gain blocks in a number of places would dramatically reduce the complexity, cost, and component count while improving performance.
WA8TOD
|
Re: Which xmit transistor is blown?
Ok, I think I have this solved.
Really short version:
It appears that my major problem was the laptop that I was using for FT-8.? The laptop that I have been using is not putting out consistent volume/drive on wsjt-x with ft8 (even with a different sound card).? A different computer was tried and everything now works fine.
Longer version:
Ok, I'm a bit at a loss for 'why' this has happened, but here's what happened.? I spent a LOT of time tracing the transmit signal, going back through the mixer stages and into the mic amp (q6).? What I started to notice was that everything looked just great at DC levels, but when under drive ('tune' signal from wsjt-x), the signal levels and frequencies didnt seem to make sense.? I connected a commercial hf transceiver up to the same PC (which I hadnt done, as I didnt have access to one) and discovered that it was doing the SAME thing - effectively no output.? ?I tried a different sound card (usb connected) with the same problem.? When I switched to a different PC with the commercial transceiver, TWO things were discovered:? 1) suddenly I had signal coming out and 2) the transceiver was warning me of high swr.
so...high swr.? It appears that my tuner was set up incorrectly (mfj-971 - has 2 internal jumpers that have to be set for qrp operation, and the swr movement was incorrectly set), and I was likely running high swr for quite a long time with my ubitx and not realizing it.?
Once I got the tuner situation dealt with, the commercial rig works great with the NEW laptop, and still does not work well with the old laptop.? The ubitx ALSO works well with the NEW laptop now.? Whats really odd is that the OLD pc's soundcard still works fine with earbuds, just not driving either radio.
so...what I'm left with appears to be an odd pc situation (inability to drive the radio, but no other noted malfunction), but functioning radio gear.? If anyone has ideas on that, I'm open to them, but I'm not going to expend much effort in that area.
THANK YOU to those who posted and emailed me things to check.? I got into radio in order to learn more about electronics, and that is absolutely happening
73
Sean
|
Re: 2N2222A vs 2N3904 sourcing
Assuming the MMC amps can work without the issues that are being pointed out, the idea of using an assembled amplifier board, for us retrofitters (like the assembled filter boards folks are creating) might make mods easer. Here is an amplifier I bought on Amazon. The Mini-Circuits amplifier looks like it has better spec for use in the TX chain. But, this board cost $10.99 (and I have it here). If only 10DBm output drive is usable, it has a little more gain (oscillation caveat noted). I saw similar boards for less money, elsewhere.? Would be interested in knowing if this LNA might be up to par for the TX chain. I believe the board is using this LNA chip.?  Tom, wb6b
|
I just noticed that from the first picture it's not so clear about what connector I was talking about, so I'll upload a new picture.? 
|
Hi everyone, again! Today I got a really big present from PostNord Danmark. They arrived at my house with a small box shipped from INDIA. Of course, it was my new uBitx. Yay !?The shippment was partially tracked by India Post and thereafter Mumbai Airport the tracking was available on PostNord.? ?It couldn't be better than TODAY. Cautiously I opened the pack, wondering about the condition of the board, everything was looking in perfect state. But suddenly I noticed at least three strange things. One of them is a "new socket" on the board and I can't find any indication of what its use might be and where should I wire these new pins. On my board, two of the pins are listed as "CW 2" and the other two pins as "P3". Few minutes later I had the schematic on the screen, following the trace of the circuit. In the schematic that new socket is listed as "CW 1" and "CW 2" but I can't follow how can it be P3 on my board. So, I'll appreciate any information about this situation and I apologize if this situation has been previously disscused.?  One of the other strange thing for is involving the soldering of the transistors and coils. I am not a professionist but I think the holes in the board, where the pins of the components are inserted on the board, should be full with soldering tin. Am I wrong? I checked for continuity all around the places where I got suspicious feelings but everything looks great. It can be a problem for future if those holes are not filled with soldering tin? I know that these boards, in theory, are tested before shipping but somehow It's hard for me to take this for granted. I respect Ashar Farhan's job and initiative, I'm grateful for this, but let me have my reservations in this matter. I appreciate any comment. Thank you ! 
|
Re: 2N2222A vs 2N3904 sourcing
Allison, why would the MMICs oscillate and not a 2N2219A? Might screening of the mmic help?
Il 14/set/2018 18:06, "ajparent1/KB1GMX" < kb1gmx@...> ha scritto: >>>The Mini-Circuits ERA-5+ MMIC is a single, pin head sized gain block that provides 20 dB of gain nearly flat out to 4 GHz with a 1 dB compression point at +18 dBm. It is 50 ohm in and out and works great on 12V. Three of these in series would make an extremely low component count, 60 dB gain block that is absolutely flat for the frequency range involved.<<<
Warren,
Both Jerry and I tried? that.? I use MAV11 a lower gain higher output part
and getting to oscillate in ubitx environment was trivial.? Getting non-oscillation
was very very difficult.? Jerry tried as a replacement for RV1 I tried at pre Q90,
and also as replacement for Q90.? Board layout was not friendly.
I did try the 2n6661 (VMOSfet) for the drivers and at first pass they were very good?
but most people would choke on the price ($15 ea).? Never tried BS170 or 2n7000
as those are fairly decent to 100mhz as wide band amps at moderate power.
Allison
|
Re: retrouver 7.150 ¨¤ la mise sous tension
Expliquer en anglais, s'il vous plait.
Allison
|
Re: 2N2222A vs 2N3904 sourcing
>>>The Mini-Circuits ERA-5+ MMIC is a single, pin head sized gain block that provides 20 dB of gain nearly flat out to 4 GHz with a 1 dB compression point at +18 dBm. It is 50 ohm in and out and works great on 12V. Three of these in series would make an extremely low component count, 60 dB gain block that is absolutely flat for the frequency range involved.<<<
Warren,
Both Jerry and I tried? that.? I use MAV11 a lower gain higher output part
and getting to oscillate in ubitx environment was trivial.? Getting non-oscillation
was very very difficult.? Jerry tried as a replacement for RV1 I tried at pre Q90,
and also as replacement for Q90.? Board layout was not friendly.
I did try the 2n6661 (VMOSfet) for the drivers and at first pass they were very good?
but most people would choke on the price ($15 ea).? Never tried BS170 or 2n7000
as those are fairly decent to 100mhz as wide band amps at moderate power.
Allison
|
Re: 2N2222A vs 2N3904 sourcing
Allison, Yes, it's like herding cats ......? many different ideas, many cats. 73 Kees K5BCQ? ajparent1/KB1GMX
Ralph yes right here about 6 wweeks ago.
We repeat everything here at at least 5 times.? Sometimes more.
Allison
|
Re: 2N2222A vs 2N3904 sourcing
I have ordered many small parts off ebay from China.? One has to be very careful as there seem to be many substandard parts.? You may get a good batch from one source and a bad batch from another.
I have some RF power transistors of the 10 to 20 watt range.? They do now work at 10 MHz and above at all.? They do seem to work ok at DC and audio frequencies.? So will use them in audio output circuits.
de ku4pt
On Fri, Sep 14, 2018 at 11:13 AM Warren Allgyer < allgyer@...> wrote: Sorry Iz, I mis-typed. It is the ERA-3SM+ that is available for less than 1USD on eBay. It is from a Chinese supplier so it will require due diligence in testing.?
? I have them on order for test.
I have a MMIC amp from SV1AFN with similar specs that I just tested. Very clean, 23 dB of gain. A two tone test showed it does IMD of -50 dBc at -5 dBm out. It did -24 dBc at +5 dBm out. I will run similar tests on the 70 cent chinese ERA-3SM upon arrival.
WA8TOD
_._,_._,_
|
Re: 2N2222A vs 2N3904 sourcing
Ok Warren, sv1avn is a good supplier as rf-microwave is, of course if you test the mmic from the Chinese supplier are ad good too I might well consider it. Thanks for testing them and keep us informed!
Il 14/set/2018 17:17, "Warren Allgyer" < allgyer@...> ha scritto: The 23 dB gain, 2.4 GHz MMC amp module I tested is here:?? ? ?It costs $17 delivered from Greece.
WA8TOD
|
Trystan G0KAY
YO8UFO