Hello Kc7noa,
The latest schematic can be found on GitHub. Link given below:
TX1-1-13MA has impedance ratio of 1.
Regards,
Karolis
What would have been first choice?
Utterly disappointed with Lime. If as I expect this DIY fix will be the final word on the matter Iāll be jumping on the refund band wagon. Not even an apologie, I canāt help wonder what other specs they have ignored.
3 Likes
Why dont you make another version with these fixes?
No, Myriad RF should do it for me!
Thanks for the measurements results. Studying the results created some new questions:
First I think figure3 is missing.
The input frequency is swept from 100kHz to 1GHz. What LO values and filter settings were used in the HF band?
It was stated that āAll networks show a fall in level below 30MHz due to internal design of the LMS7002M. āI had a quick look in the LMS7002M datasheet, but I saw no explanation except maybe the use of a narrow baseband filter. Could you explain what block causes the additional attenuation? Is it a real degradation or is just a digital scaling factor caused by digital filtering?
What happens with Transmission in the HF band? Do we have the nominal output power or are the output power values for HF also 40 -80 dB lower?
It was stated that āthe Noise figure of the same (broadband) network was measured on an evaluation board and found to be 10dB at 30MHz. Is that including the effects caused in the LMS7002M or was the NF measured at the input of the LMS7002M?
Cornelis DG7SEH
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Warning: Optimizing information LimeSDR matching for HF, By Danny Webster 10th February, 2017 has no value.
Be much more vigilant please.
It is regrettable that the information you have just given us concerns the components of Version V1.2 and that you should normally intervene on version V1.4, where the components do not have the same values.
Bernard MALET
I would have chosen a Hermes if I was on a budget or a full Anan 200 model with Angelina for exclusively HF use.
I have a full HPSDR set here for just that, the Lime SDR would have to be some serious kind of kit to even get close to that set on HF.
It is such a shame that so many focus on HF as the big boy arena, all the real activity is happening up in the microwave regions now with HF being mostly contests it seems these days.
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I am surprised to hear that from the U.K. call sign holder. Most of us know that OFCOM āsqueze your ballsā by taking away most of the 2.3 and 3.4GHz in the U.K. The compensation is 1MHz extended 2m band 146MHz. In the Germany and Austria they just sweep the wideband transmission on 1.3Ghz and most of the ATV is banned due to treat to the Galileo navigation system that failed recently due to master clocks stop working. 5.7Ghz is polluted with the Wi-Fi and weather radars. Wi-Fi is migrating in some EU countries even to 10Ghz and 24GHz.
To be honest, I do not see much activity on higher uW bands either. Myself, the total QSOs made per year on 24Ghz, 47GHz, 76GHz and 122GHz is not passing the number 20! So what activity on uW bands we are talking about? uW bands are interesting but very expensive. HF is much more used and much more activity. Anyway, soon we will loose the rest of the uW bands we have access to.
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Thereās plenty of available real estate in the UK microwave regions:
http://rsgb.org/main/operating/band-plans/microwaves/
As for the LimeSDR, it is what it is. Anyone expecting huge amounts more for the same price were fooling themselves.
I bought it for what it is and where it can go and what it can run. HF was never going to be a performer for anyone who paid attention to the fact that it took right up to the last second to get HF and even then it took some trickery on the hardware to do it. Want HF SDR performance on the cheap? Hermes is really the only option.
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I bought this I imagine like a huge amount of people with a limited knowledge of SDRs and coming directly from the Realtek dongles yet very much looking forward to learning more with a much more capable and refined unit. I havenāt received it yet but the lessons are coming in thick and fast, not ones Iāll forget either.
Or is it my fault, did I miss the warnings people posted during the campaign ?
@M0GLO there is also the https://github.com/softerhardware/Hermes-Lite2 but it is a DIY and looks to be around $200 in parts. Looks fine for HF to 30MHz if I am reading it right.
I just did the mod on my 1.4 board after talking with @martywittrock it is now working on HF and I have AM band signals alsoā¦
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Could you show us a screen shot or video? Iād also be interested in the exact part locations your replaced. Iām willing to try the mod also.
-Freeman, N5FPP
just editing photo now
Dang those caps are small - I donāt think I have any that size. I will need to order them.
-Freeman, N5FPP
All I did was remove the small SMT coil to reveal the solder pads, it actually popped off with a slight touch
circled in yellow this is for the RX1_L connector, could do the same for the next one for RX1_W, you can see that one still in placeā¦
4 Likes
Wow day and night - Iām listening to 2.5Mhz WWV right now - FM sigs still show, but I have a external filter for that.
I hear some stability problems with the signal, it slides up and down just enough to be noticed in the tones.
-Freeman, N5FPP
not sure how much difference changing the other components in easy fix one will make, but just taking out MN18 is all you need to do I thinkā¦and most people will be happyā¦
