Re: LMX2541

Robin Szemeti - G1YFG

What would be useful, but unfortunately does not exist in the KST protocol, is some way to indicate which bands you are QRV on, sadly, this was not designed into the protocol specification and relies on people altering their display name as they see fit ... a nasty kludge ... sorry software, I'll shut up ;)

Anyway, back to throwing bits of circuitry at PCB ...  getting there, but still a long way to go,   had to go 4 layer in the end. 

On Fri, 10 Jul 2020 at 13:56, Andy G4JNT <andy.g4jnt@...> wrote:
It doesn't help that people STILL keep referring to the bands by their approximate wavelength.
It's the 3.4GHz band, not 9cm, etc.

More keywords to alert on in KST 

On Fri, 10 Jul 2020 at 13:15, Robin Szemeti - G1YFG <robin@...> wrote:
Yes, sorry, old habits ...  its like all these weird people moving from 2320 to 2300 .. new fangled frequencies, it will never catch on.

On Fri, 10 Jul 2020 at 13:09, Daniel <dko1@...> wrote:
Hi Robin,

you won't work many on 3456 these days.
Try 3400 Mhz.


On Fri, Jul 10, 2020 at 01:58 PM, Robin Szemeti - G1YFG wrote:
Hi Paul,
I have some and I did consider that .. in the end, I have decided to go a bit more modern and use an IQ modulator. If I have the phasing right it should produce just the lower sideband, but equally, I might have it 90 degrees out and it won't ... so you'll either hear me on 3456MHz .. or possibly about 1606 MHz above there. I should say the chances are 50/50 either way at this point ;)

On Thu, 9 Jul 2020 at 00:29, PAUL NICKALLS via <> wrote:
Hi Robin,

I made a pipecap filter for 3.6214 Ghz It was quite narrowband and had an approx 3dB loss.  You can play with loss and bandwidth by adjusting the probes.  I have a bag of 28mm pipecaps here if you want one. A bit old school but quick and easy.

Paul G8AQA

On 08/07/2020 23:43, Robin Szemeti - G1YFG wrote:
I'm doing a board for the Ionica units .. so  144 in/out  .. and then a 947->144 receive convertor, and a LO feed to drive the Ionica receive block to do the 3456 to 947 conversion.    On the transmit side it will do the same trick in reverse and produce 10mw max of 3456 to drive the Ionica PA. I've sourced a SAW filter for the 947 segment, I just need to figure out the best solution for a 3456 filter ...   the 144/947 will be done with active mixers, the MAX2680 / MAX2671, I'm thinking something from the Minicircuits lineup for the 947->3456 upconvertor.
Slapping one of the LMX2451 units onto a PCB would be simple enough, I think JNT has done this already though.  If there is interest, I could do that, but probaby best to let me iron the mistakes out on the 9cm board and then pick up the lump of LMX off that board and slap it onto a PCB. I have an SMT machine in the shed, assembling them would be simple enough.

On Wed, 8 Jul 2020 at 23:12, Paul Randall G3NJV <paulfrandall@...> wrote:
Robin,  Hi, not sure of your intentions but if you get  a pcb made for the lmx2541/ pic etc or purchase chips,  i would be very interested in several boards and chips and happy to share costs. This is such a useful item I imagine a lot of people "could"  be interested in a group buy, so perhaps worth asking?
I really enjoy following your posts,  thanks,  Paul, G3NJV
Sent from my Samsung Galaxy smartphone.
-------- Original message --------
From: Robin Szemeti - G1YFG <robin@...>
Date: 08/07/2020 00:06 (GMT+00:00)
Subject: Re: [UKMicrowaves] LMX2541
I was planning on using one of those 0.28ppm crystals you noted the other day at 10MHz, or possibly the 10MHz reference out of the 70cm linear.

On Tue, 7 Jul 2020 at 21:56, Andy G4JNT <andy.g4jnt@...> wrote:
Need to add ...   providing the loop filter is done right  :-)
With a loop bandwidth of a few tens of kHz then the output will take on the (multiplied) phase noise of the reference.  Use a decent  reference, and you've got yourself a decent uWave  signal; at least out to +/- the loop filter bandwidth.

On Tue, 7 Jul 2020 at 13:05, Robin Szemeti - G1YFG <robin@...> wrote:
Perfect, that's all I need to know :)

On Tue, 7 Jul 2020 at 12:23, Andy G4JNT <andy.g4jnt@...> wrote:
Perfectly OK 
There are one or two UHF beacons using them, generating JTxx modulation by reprogrammong (Reg 2 !!!) in real time
G8BKE (or is it G8ACE) is even using one at 47GHz

On Tue, 7 Jul 2020 at 12:03, Robin Szemeti - G1YFG <robin@...> wrote:
Generally speaking, how good is the phase noise on these things for low noise, SSB stylee applications?
I was thinking of using a couple of these to get one of the Ionica units down to 145 MHz.  I'd just like a "yep, they are great providing the loop filter is done right" ranging to "avoid like plague, only suitable for consumer electronics"  sort of ballpark idea, so I know if I am wasting my time pasting them onto a PCB with some mixers.

Best regards,

Robin Szemeti

Redpoint Consulting Limited 

E: robin@... 
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