Hi Greg
The Irwell transceiver did start off with the intention of it becoming a kit however the project has taken me way longer to develop than I ever anticipated. So far I have the multi-mode receiver stages complete which includes a digital modes interface. The receiver stages include two high performance H-Mode mixers that are also used in the transmit section so I can say the transmit sections are part complete!
I am currently working on the transmit multi-mode modulator section and expect delivery of the TX Microphone pre-amplifier & VOX pcb's within a few days so good progress is being made.
There are many reasons why this project is taking so long to complete though mainly due to a lack of time, I have used up a lot of time building and testing different modules before deciding on what would make it to the final build.? I have lost count of how many AM demodulation methods I built and tested before deciding on the AD8361 detector IC and the same can be said for some of the other modules too.
Early on I decided to develop the Irwell transceiver in a modular fashion so that the project could evolve over time and be presented in manageable chunks but it soon became apparent to me that with so many modules the transceiver would become rather large so I switched to using SMD components to shrink the modules down in size.? The use of SMD technology will alienate a lot of people and therefore reduce interest in the project but I would urge anyone in home brew construction to try SMD and suffice to say if you can solder 1/4 watt through hole resistors you can solder 1206 size SMD parts!.
Now having alienated some users with the use of SMD technology and lost other users interest with the long and drawn out project progress I return to the question "are there plans for an Irwell kit"
At this time I am not sure there is sufficient interest to warrant producing a kit for the Irwell transceiver however once the project is complete I will see what interest is shown and re evaluate this. As a minimum I will make PCB's available and possibly arrange a group buy on some of the parts.
To conclude I think it is fair to say this project has become a bit of a personal crusade but I hope that the project does generate some interest and gets built by other fellow enthusiasts. I will be posting more details shortly on some of the other completed modules so keep an eye on the files section of the group.
Regards & best 73's
Andy de G6LBQ
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Are there any plans for Irwell to become a kit in any form ?
gregW:-)? OH2FFY
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Hello to all,
letting you know Andy has downloaded 4 files about the latest project The Irwell Tcvr,
Have a look, it is what we have been waiting for and there will be more to come hopefully asap
73 G6YAQ
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Hello Andy,
Many thanks for postiing the 4 files and pic's for the latest Irwell tranceiver build (with more hopefully to come in the near future.
I am sure they will be viewed by many members who are interested in your next? project and will appreciate the many hours of work you
have applied to get to this stage,it's what we need for an excellent tranceiver this is going to be for us
I'm sure it will be a good talking point on the group,keep up the good work Andy!!
Frank G6YAQ
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Andy, Jerry and the forum,
Thanks for your suggestions to tame my G6LBQ transmitter instabilities.? I haven't had time until no to respond more than briefly. I found that the speaker-mic I was using was un-shielded and acting as an antenna, coupling RF back into the Q5 stage.? It probably didn't help that the thing was sitting on the bench opened up. An alum sheet case lid may have helped.?
Regardless, I have ditched the speaker-mic and have reverted to an inbuilt electret condenser mic element, built right in at the mic amp input.? What confused me is that the RF feedback did not decrease when I took +12v Tx off the mic amp stage. So the speaker-mic cable must have been coupling RF back into Q5, not the mic amp.??
I made up some brass plate shields to fit over the first mixer (ADE-1), MC1350 stage (probably not necessary as this stage is not powered in transmit, but good practice for oscillator shielding anyway), and mic amp including the electret mic.? If I turn up the PA bias sufficiently high, the RF feedback returns.? I will do more work on shielding the PA stage, and band pass filters.? For now, the little rig appears to be usable, so I'll try it for a while 'in the field' before further work.? ? ?
On Sunday I?strung?up?a 40/20m trap vertical in the back yard, and stood under it, holding the G6LBQ walkie talkie, on a LiFePO pack, listening to 20 and 40m. On 40m it is as sensitive as anything else I've built.? 20m is just dead all the time.? But band conditions were terrible, I ran out of time, and didn't attempt to try to make contacts.
Hopefully I'll get up to a SOTA summit soon for a real test of this G6LBQ build.
73 Paul VK3HN
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul
Great to hear you have made progress with the instabilities.
On looking back at the forum messages I gather that you have built the Linear amplifier with three RD16 mosfet devices ?
If so be careful with excessive gain in the transmit stages, the HF linear with three RD16's has more gain than is needed. Q13 (2N5109) produces around 400mw output which makes the 1st RD16 driver somewhat redundant!??
The 2N5109 in conjunction with just the two final RD16 devices should produce around 8 watts.
The original 3 X RD16 HF amplifier was designed for the MK1 transceiver and the standard BitX transceivers that did not contain the 2N5109 driver on the exciter PCB.
To clarify the Linear amplifier with 3 X RD16 can be used with the G6LBQ MK2 Exciter but the RF from the exciter must be reduced, the original linear amplifier PCB contains a PI network attenuator before the 1st RD16 and this must be used to avoid instability and overdriving the amp. In reality this is a waste of energy but some builders have used the extra gain to push the output above 10 watts but you then have to question the transmit linearity!.
Regards
Andy G6LBQ
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Re: Mk II Scratch-build May 2018 -- some questions
Andy, things have moved along, the problem I was having appears to have been due to using an unshielded speaker/mic, I've ditched that, added an inbuilt mic, added shielding, and set the mic amp gain low. It's working, although there is still a bit too much carrier leakage thru the exciter and into the PA. However much better.? Will post a blog entry and video soon.? Regards Paul VK3HN.?
On Sat, 8 Sep. 2018, 20:43 g6lbq via Groups.Io, <ah.electronics= [email protected]> wrote: Hi Paul
One quick question, are you sure that the carrier oscillator is aligned correctly, poor alignment and you may be experiencing some leakage.
Did you match your crystals for the SSB filter ?
I doubt that the MMBT3904 transistors are causing a problem.
Sorry I am late in jumping in on the thread but due to ongoing family health problems I have not been active in the group but will read through the thread and see what else I can add.
Regards
Andy
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul
Can you try the following;
Disable the final linear amplifier stages so that you only generate RF as far as Q13.
Is the instability still present?
73 Andy
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul
One quick question, are you sure that the carrier oscillator is aligned correctly, poor alignment and you may be experiencing some leakage.
Did you match your crystals for the SSB filter ?
I doubt that the MMBT3904 transistors are causing a problem.
Sorry I am late in jumping in on the thread but due to ongoing family health problems I have not been active in the group but will read through the thread and see what else I can add.
Regards
Andy
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul - I have no experience with the G6LBQ design but I lurk here occasionally to see what is going on. The issue you described is a frustrating one for sure. After reading about your experiences and reviewing the schematic I have a few questions:
What happens if you eliminate any signals?going into?the base of Q5? I would first lift the 100n cap on the base input and see if Q5 behaves. If so then put the capacitor back in and pull the 22R from the attenuator after the ADE1 mixer. If Q5 is still acting up then pull the 100n capacitor going to the MC1350.
I know the 1350 should be off in transmit mode but what if it is somehow getting powered in TX mode?? It is kind of a long shot but I think you have explored all the more reasonable causes so we need to look for something a little crazy. Hang in there and you will get it. Good luck.
73 - Jerry - W0PWE
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul,
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Maybe your problem is coming with high SWR or incorrect matched stages ? I had such problem in my project.?
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Regards
George
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W dniu 2018-09-06 07:51:19 u?ytkownik Paul VK3HN <prt459@...> napisa?:
Thanks for the suggestion George.? Common base presents an ideal low input impedance which is desirable.? What I am doing here is reproducing the G6LBQ design, which I assume has been built hundreds of times successfully. What is unique to my build is my board and layout, which could be the cause of many instability ills.??
That said, all of the tests above lead me to conclude that the problem is confined to the vicinity of Q5.? My construction is all SM on a hand made PCB, the layout separates output from input, and there is plenty of ground plane around and underneath the stage.? So it must be something else...
73 de VK3HN.?
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Re: Mk II Scratch-build May 2018 -- some questions
Thanks for the suggestion George.? Common base presents an ideal low input impedance which is desirable.? What I am doing here is reproducing the G6LBQ design, which I assume has been built hundreds of times successfully. What is unique to my build is my board and layout, which could be the cause of many instability ills.??
That said, all of the tests above lead me to conclude that the problem is confined to the vicinity of Q5.? My construction is all SM on a hand made PCB, the layout separates output from input, and there is plenty of ground plane around and underneath the stage.? So it must be something else...
73 de VK3HN.?
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Re: Mk II Scratch-build May 2018 -- some questions
Hi Paul,
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Try to do something with common base for whole of RF stages. Sometimes it works.
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73
George sp5rzm
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W dniu 2018-09-06 01:15:26 u?ytkownik Paul VK3HN <prt459@...> napisa?:
Update on this scratch build -- the receiver is working well, I use it on 40m regularly.? But the transmitter is unstable. I've returned to it over the last few days to see if I can iron it out.? Recap, this is a scratch (mostly surface mount) build, exciter on one board, Nano/LCD/encoders/switches/si5351 with 2n2222 clock buffers on all clocks on another board, predriver/driver/single RD16HHF1 PA and LPFs on another board.? TDA2003 audio amp replaces the LM386.? Otherwise as per G6LBQ Rev 1.6.??
To cut a long story short, it looks like the first IF amp in the transmitter is unstable (Q5).?
The symptom is that when PTT is pressed, the transmitter produces SSB but it is dirty and full of RF feedback; the signal looks rough on a scope; the power meter kicks up with speech as expected but sits about half power between speech input with all the crud.?
This is what I know so far:
-- if I remove the RF input from the exciter board to the PA board everything after that (predriver, driver, single RD16HHF1 PA) is stable => PA is not the problem?
-- if I inject a few hundred mV of 7MHz signal on the base of the driver I get a healthy 5 or so watts output => PA is working as expected??
-- if I remove the +12v Transmit to Q5, everything after that is stable; touching the crystal filter input or output injects noise which? can be heard and seen on the scope => everything from the second IF amp to the PA is stable and working??
-- if I put +12v T back on Q5 but remove it from the mic amp, there is no change => instability is not coming in thru the mic amp?
Another observation -- when Q5 is powered up and in transmit, it (or something) puts a horrible 0.5v signal at roughly the signal frequency (or it could be the BFO frequency, I can't tell with my cheap scope) on the 12 DC supply line, which makes its way to the si5351, and causes the 2 clocks (VFO, BFO) to be distorted.?
-- if I short out the input to Q5 (to earth) while this stage is powered, the instability stops => Q5 is oscillating .?
The whole thing is securely mounted in an aluminium case.?
There is all the usual 100nF decoupling.? I wound the +12v Tx supply wire to the exciter transmit stages thru an FT37-43, no impact.? I wound the short +12v Tx wire supplying Q5 thru an FT37-43, no impact.
The power supply is a 12v 5amp commercial quality regulated overload protected supply.??
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At this point I suspected a wiring or component error in the Q5 stage. I have checked all voltages and they are within? about 20% of the pre-driver stage which is similar.? All component values look the same.? I wonder if the output coupling capacitor Cs is 100pF or whether I might have put in a 100nF as these are SMD unmarked.? But I dont think that would be the cause.
if anyone is still reading, does this ring any bells for anyone? Has anyone else had a similar problem?? ?How is the crud finding its way onto the supply lines at such a high level?? Does this stage (Q5) exhibit high gain with some MMBT3904s???
If I cannot tame it at my next bench session, I may remake the Q5 stage on a postage stamp board with all new components and layer it over the top to ensure all components are correct. I may also use a 2N3904 rather than the SM MMBT3904, whose gain may be less predictable, although these SM transistors are behaving in the other transmit and receive stages, other than the first RF stage, which is the MPSH10 as per the design.?
Other suggestions welcome.
regards Paul VK3HN.??
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Re: Mk II Scratch-build May 2018 -- some questions
Update on this scratch build -- the receiver is working well, I use it on 40m regularly.? But the transmitter is unstable. I've returned to it over the last few days to see if I can iron it out.? Recap, this is a scratch (mostly surface mount) build, exciter on one board, Nano/LCD/encoders/switches/si5351 with 2n2222 clock buffers on all clocks on another board, predriver/driver/single RD16HHF1 PA and LPFs on another board.? TDA2003 audio amp replaces the LM386.? Otherwise as per G6LBQ Rev 1.6.??
To cut a long story short, it looks like the first IF amp in the transmitter is unstable (Q5).?
The symptom is that when PTT is pressed, the transmitter produces SSB but it is dirty and full of RF feedback; the signal looks rough on a scope; the power meter kicks up with speech as expected but sits about half power between speech input with all the crud.?
This is what I know so far:
-- if I remove the RF input from the exciter board to the PA board everything after that (predriver, driver, single RD16HHF1 PA) is stable => PA is not the problem?
-- if I inject a few hundred mV of 7MHz signal on the base of the driver I get a healthy 5 or so watts output => PA is working as expected??
-- if I remove the +12v Transmit to Q5, everything after that is stable; touching the crystal filter input or output injects noise which? can be heard and seen on the scope => everything from the second IF amp to the PA is stable and working??
-- if I put +12v T back on Q5 but remove it from the mic amp, there is no change => instability is not coming in thru the mic amp?
Another observation -- when Q5 is powered up and in transmit, it (or something) puts a horrible 0.5v signal at roughly the signal frequency (or it could be the BFO frequency, I can't tell with my cheap scope) on the 12 DC supply line, which makes its way to the si5351, and causes the 2 clocks (VFO, BFO) to be distorted.?
-- if I short out the input to Q5 (to earth) while this stage is powered, the instability stops => Q5 is oscillating .?
The whole thing is securely mounted in an aluminium case.?
There is all the usual 100nF decoupling.? I wound the +12v Tx supply wire to the exciter transmit stages thru an FT37-43, no impact.? I wound the short +12v Tx wire supplying Q5 thru an FT37-43, no impact.
The power supply is a 12v 5amp commercial quality regulated overload protected supply.??
?
At this point I suspected a wiring or component error in the Q5 stage. I have checked all voltages and they are within? about 20% of the pre-driver stage which is similar.? All component values look the same.? I wonder if the output coupling capacitor Cs is 100pF or whether I might have put in a 100nF as these are SMD unmarked.? But I dont think that would be the cause.
if anyone is still reading, does this ring any bells for anyone? Has anyone else had a similar problem?? ?How is the crud finding its way onto the supply lines at such a high level?? Does this stage (Q5) exhibit high gain with some MMBT3904s???
If I cannot tame it at my next bench session, I may remake the Q5 stage on a postage stamp board with all new components and layer it over the top to ensure all components are correct. I may also use a 2N3904 rather than the SM MMBT3904, whose gain may be less predictable, although these SM transistors are behaving in the other transmit and receive stages, other than the first RF stage, which is the MPSH10 as per the design.?
Other suggestions welcome.
regards Paul VK3HN.??
?
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This design is based on BiTx, bidirectional transceiver. The BPF is symmetrical.? It's in circuit in both tx and rx, depending on where the +12v is applied (rx stages or tx stages), kef tto right when receiving, right to left when transmitting.? ?
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On 23/08/2018, Sakti Mukherjee <newsakti@...> wrote: I am building a MK2 version in a modular form (stage wise) using the
Manhattan method.
BPF Question - Is the BPF common to both RX & TX (with no change at all) ? it's same if U using 50 ohm antenna... U might experience re-adjusting BPF a little every time for best RX, if using variable length long wire, while calibrating... Thank you.
5Z4BT
-- Please encourage recycling, reuse or repairing of E-waste. ?7?3? ?d?e? ?V?U?3?S?X?T?
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Paul VK3HN