Weird imaging from 500 MHz++ on 100 MHz++

yeah… this is not an option for me. it is simply the opposite of the concept of an SDR in my opinion.

wonder if a tracking filter is do’able … to 3.8Ghz …

I plan on using isolators for microwave … they are narrow enough for me …

Anyway, i’ve written an email to limemicro concerning this problem.

What problem? I do not see a problem with the Lime in this respect. The problem that you perceive is of your creating not of Lime’s. You have an antenna that offers little to no filtering and you have installed no filters between the antenna and the Lime.

I would say that the Lime is working perfectly for the set up that you have mentioned that you run. OBVIOUSLY it needs the user to install filters for the particular parts of 100Khz to 3.8GHz that they want to use. Why on Earth would you expect it not to need filters? it is the users job to choose what frequencies they want to TX/RX on and build a filter (and antenna) for those.

1 Like

Filters, like antennas and PAs etc. are application-specific and should be selected as appropriate by system builders.


Exactly. On 6m for instance I have a choice of 3 filters depending on if I want to run on the SSB, EME or Digi sections of the band. And that is if I am running my ANAN, my FCD+ or even a Brick RX. Why on earth would I expect my RX to work to its best without any filters or even without a real antenna. There is no antenna that I am aware of that covers 0 to 3.8GHz but if you would like to buy one that does then I will be happy to send you my Paypal address. Antennas are “tuned” for where you want to TX/RX just in the same way as a “tuned” filter needs installing.

There’s nowt so queer as folk…

1 Like

That’s what I’ve been on about, soo many who didn’t understand…

It’s also why I don’t market to the Ham crowd.

That is why, to me, the inductor was a problem. It was a de facto filter. Once the solution of removing the “filter” was put forward then the Lime became what it was advertised as. The SDR Console pictures above are fantastic. They tell me @c5e3 lime is working perfectly which is wonderful to see.

1 Like

Sorry not SDRC. I should have scanned back up to confirm what was in my head rather than realising there is nothing much in there…

As I like to be positive rather than negative can I suggest that for those looking for a simple LPF or BPF for HF that you look at the ones available from QRP Labs. They have LPF’s that cover HF and go up to 222MHz. They are very easy to build. I use these on the N4EME club U3S Digi beacons for TX. Once the TX/RX beacons go into service then they will be used for both.

Because other SDRs have tuneable filters built-in. I simply didn’t expect to have mirror images.

However, i got the point now and found out, that i actually just need a LPF with a cut-off frequency of about 200 MHz, which is easy to build.

Harmonic operation works actually quite well without filters - 5 GHz can be received!

And it says OXO on the side of buses but they don’t sell them.

Am I correct in understanding that you bought a Lime without paying any attention to what you were buying so now you are looking to blame Lime for them not building what you wanted rather than you not wanting what they built?

My interpretation is that you wanted Lime to be a Flex 6$$$ but cover upto 3.8GHz and now you are upset with Lime because that is not what they sent you? The pictures you posted show your Lime working perfectly as I would expect it to work.

As previously stated the problem with Lime that most people initially complained about, me included, was the installation of a de facto filter. Once removed the Lime works as advertised. I am sure you will be very happy with your Lime once you install the correct antenna and filters. I think I can say with confidence that the Lime is the best SDR TX/RX on the market that operates up to 3.8GHz. Hell it is even the best TX/RX 2m SDR out there and seems to be the equivalent of a TS2K on 2m.

I am sure many of us will be happy to discuss filters and antennas with you based on your needs. Again though remember there is not 1 filter or 1 ant that does 0 to 3.8GHz. Most antennas are good for between a few 100HZ and a couple of MHz depending on the frequency and the design. With regards to filters most people want as narrow a filter as possible.


Perfect! On 2m I did find that I really needed a BPF rather than a, say 200MHz LPF, as I have a very strong FM broadcast station within 10 miles which was being a pain. On 222 I found that I did not really need a filter at all as the part of the band I was listening to fell in a quiet spot. On HF I just threw in a cheap 30MHz LPF and Bob’s your Uncle.

I will! As I said, I just didn’t expect that I have to use filters. And you’re right - it works perfectly :slight_smile:

222 MHz is anyway uninteresting for me since it is not a ham band in Austria. I will try a LPF since i have a FM broadcast notch filter too.

Just drilled and filed the holes for the connectors and assembled my aluminium case. I have to pay attention to the temperature though, I think I will add a small fan.

It looks very neat.
I left the bottom 5 holes free to allow some air flow.
I had the lime plugged in for 2 weeks solid and I was happy with the coling.
But that is just me. I want an even temp that does not change too much so as to affect the frequency stability.

Build an internal tower that uses a thermal pad to touch the hot IC’s … the tower bonded to the case. To use the case as a heatsink