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Re: WG16
Adrian whatmore <g4uvz@...>
Thanks to all for the various comments and sources of info and also hardware..I guess that nothing worth while is that easy to achieve! Adrian
On Thursday, 4 August 2016, 0:19, "Christopher Bartram cbartram@... [ukmicrowaves]" wrote: Hello Adrian
I'll write this to the group, as it is of general interest. LDF4-50 is not a particularly sensible choice of coax at 10GHz: I think the manufacturer rates it to about 8GHz. Counter-intuitively to many people's ideas, it's diameter is too large to use use reliably at that frequency. It can work very well, but it can also work as a very good attenuator, with an attenuation figure of 20+dB worse than might be expected. This is due to higher order wave propagation, where energy combines with the wanted signal propagated in the simple transverse mode either constructively or destructively: an effect which can be quite temperature dependent. I've been there, and spent a lot of time scratching my head before I realised what was happening It's better to use a smaller diameter cable. I have a 5m length of LMR240 which works well at 12GHz carrying the LO signal to my 24GHz transverter, but it is probably not up to use as a low-loss antenna feed. 73 Chris GW4DGU --
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Re: Coax Probes into Waveguide
GORDONJ REASON <gordonj.reason@...>
H Andy ..... made one of the WG16 filters many years back .......... I found that the response , loss and match , was improved , by fitting small screws , close the either side of the Iris's ......and the inputs , 10 or 12 BA if you can get them . iris were only soldered on the long face , a small gap on ther short face as signal did'nt get around the edge .............. I have a couple of professional filers , made from circa 16 mm section , that have sma in out ......no soldering on them , and held together with screws , will come apart .......... but have'nt taken one apart , that I remember ................... You are welcome to try one .... and examine it ..... When I was alive and employed , I belive the bandpass was 30 mhz , to -1dB ... can't remember the loss , but it was acceptable (from memory) ............ I'm located south northamptonshire ............. 73.
On 03 August 2016 at 11:12 "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:
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Re: Coax Probes into Waveguide
Hello Andy and other readers. An interesting project.....but I want to make sure that you're not presuming that a probe forming a waveguide-to-coaxial transition needs to be a quarter wavelength long - it's usually better not to be so. Apart from off-the-shelf transitions made by the likes of Hewlett-Packard (e.g. X281A), the best-matched 'probes' that I have seen are not just straight 'rods' but they look more like inverted cones with the broad end in the middle of the waveguide. And they're not a quarter wavelength long either. I have done some trial-and-error experimentation and have confirmed that probes like these have worked very well in various projects. I remember one case making a probe of increasing diameter using several pieces of brass tube of incrementally increasing diameter. (Sorry, you can't work in waveguide and avoid some metalwork!) And being a little shorter than a quarter wavelength, it is
intuitively allowable for an adjustment screw to be introduced
through the opposite wall, adding a little capacitance there. But
adjustment screws may need to be better placed at another location
and the old trick of leading a small ball bearing around inside by
way of a bar magnet held on the outside, is a great way to find
where the 'sweet spot' actually is. Approaching from another angle, a very good way of bringing any trial-end-error waveguide transition into submission is to have a close-fitting back short, the position of which is adjustable by sliding in and out a little. Known good directional couplers (waveguide and/or coaxial) are your friends here! Just a few comments to start..... Cheers and 73, --Doug Friend, VK4OE.
On 3/08/2016 20:12, Andy Talbot
andy.g4jnt@... [ukmicrowaves] wrote:
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Re: Coax Probes into Waveguide
Hi Andy, My inclination would be to put the probes in the centre of the cavity, and you will need only a very small insertion for bandwidth of the order of 1%. At least then you are coupling primarily to the intended mode in the waveguide, rather than higher modes which may produce unexpected results and add extra reactance. It is advisable to maintain symmetry as much as possible. If the input and output couplings are the same and the two irises are the same and the three resonators are tuned, the filter has to work at the centre frequency, doesn't it. The bandwidth and the ripple may not be quite what you wanted, but you know the irises are right, being from a proven design, so you have only one thing to adjust, in/out coupling. I made a dual mode cavity for 5.7GHz (with N connectors) The probes were 6mm diameter by 3mm insertion and bandwidth about 1%. That was square waveguide, yours will be rectangular, no doubt, and my intuition says that will increase the coupling somewhat. I would be tempted to start with something 3mm diameter and close to flush with the w/g wall. Easy to reduce the coupling with a shim under the connector flange. 73 es gl. G3YKI
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Re: wtd spare M57762
Hi there Simon and other readers. A couple of years ago I needed one and purchased the Icom equivalent at: https://www.rfparts.com/module/550-1300-mhz/rfpower-551-1300-icom/sc1040.html See how you go.....I still like those older bipolar modules....! Cheers and 73, --Doug Friend, VK4OE.
On 4/08/2016 17:21, gm4plm@...
[ukmicrowaves] wrote:
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Re: Timepod (was - Morion OCXO)
dbztuzujdhgtrjzthxh
In addition to Grant comments, I'll add that TimeLab is not limited to working with the TimePod.
In fact TimeLab has been available for considerably longer than the Pod and works well with many other instruments. Given the software is free, it's well worth a look. ian
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Re: wtd spare M57762
John Roberts <J.S.Roberts@...>
Simon,
I have one hardly used and mounted on a WDG017 board. The amp is in a milled box. If your interested can you contact me directly at J.S.Roberts@... Thanks John G8FDJ
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Re: Timepod (was - Morion OCXO)
Christopher Bartram <cbartram@...>
Hello Derek
Many thanks for posting the link to the NIST paper. It made very interesting reading indeed, and I look forward to hearing of your results in time. Vy 73 Chris GW4DGU --
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wtd spare M57762
gm4plm@...
local here looking to repair an amp anyone got a spare M57762 ? Even an unused amp with one will do Cheers Simon ZL4PLM zl4plm@...
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Re: Has anyone bought one of these ...........
Hi
No because you have not provided the items name. 73’s Mike g4wyz
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Re: RSGB response to 5.6 GHz demolition
Mike Willis
Personally, I thought that while it was a good response, with many good points, it was a little too robust in the language used. This risks the detail in the argument being lost while the reader recovers from the initial hard punches.
Mike
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Re: WG16
Christopher Bartram <cbartram@...>
Hello Adrian
I'll write this to the group, as it is of general interest. LDF4-50 is not a particularly sensible choice of coax at 10GHz: I think the manufacturer rates it to about 8GHz. Counter-intuitively to many people's ideas, it's diameter is too large to use use reliably at that frequency. It can work very well, but it can also work as a very good attenuator, with an attenuation figure of 20+dB worse than might be expected. This is due to higher order wave propagation, where energy combines with the wanted signal propagated in the simple transverse mode either constructively or destructively: an effect which can be quite temperature dependent. I've been there, and spent a lot of time scratching my head before I realised what was happening It's better to use a smaller diameter cable. I have a 5m length of LMR240 which works well at 12GHz carrying the LO signal to my 24GHz transverter, but it is probably not up to use as a low-loss antenna feed. 73 Chris GW4DGU --
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Re: WG16
mike G6TRM
toggle quoted messageShow quoted text
Hi Adrian,
I think you will find that flexible WG16 will not
work as a rotator loop, It was not designed to be used for large
continuous movement, but mostly to counteract vibration
problems. The only way I know that truly works would be a rotatable
joint from a large system 3cm marine radar, it will require to
be on the rotational centre line of the mast, which will be another
issue to be resolved. copper water pipe is a good alternative to WG16 but the
rotating joint issues still remains..
good luck,
best regards,
mike G6TRM
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Re: Timepod (was - Morion OCXO)
Derek Kozel <derek.kozel@...>
The US National Institute of Standards and Technology has just published a paper doing oscillator metrology using Software Defined Radios. I have access to the same receivers as they used and will be replicating their setup, hopefully in the next month. I'll be sure to post my results and experiences to this list. The radios are considerably cheaper than the Timepod, compare well in the results, and can be used as transceivers for all the bands from 70 MHz to 6 GHz. I use it as the base for my microwave rigs. https://arxiv.org/pdf/1605.03505v1.pdf
On Wed, Aug 3, 2016 at 11:12 AM, Andy Talbot andy.g4jnt@... [ukmicrowaves] <ukmicrowaves@...> wrote:
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on4kst keep getting <fsockopen connection refused >when sending spot
G8xvj@...
for the last two weeks I can't send any dx spots via on4kst it keeps coming up the this info each time I try,<fsockopen connection refused> has one had this before.
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Re: Has anyone bought one of these ...........
Neil Smith G4DBN
I bought one to see how it works. You need small fingers, but the thing does what is says on the tin. One output port is fixed frequency, selected on the top line, it has a seven-digit entry box and on-screen keypad for entry. The second output port is for the sweep function, there you set start, stop, step size and step period. You can start and stop the sweep using two on-screen buttons. It defaults to 100kHz step once a millisecond. Top end frequency is 4.4GHz as it says. After a decent warmup, it was about 4.4kHz LF at 4.000000 GHz.
Not looked closely, but there is a setting for crystal frequency set at 30MHz, so it might be possible to inject a locking reference. There is an unpopulated SMA socket location that could be for an external ref or maybe a VCO. No sign of any documentation at all. Looking at the noise, it seems to have rather noisy sidebands at -60dBc out to 100kHz, then it falls away fast to the noise floor of my 8562 at -80-ish. Could be because I am using a USB power lead inverter thingy. I'll get it on to a clean supply via the power socket instead and see how it compares. It looks like it has a programming header, and there are four push buttons which do nothing obvious. The harmonics at sub-GHz frequencies are terrible, it looks like it might be a square wave, with odd harmonics falling away only slowly, so it would need a serious LPF for anything requiring a pure tone. Above 2GHz, it is much cleaner, and at 3.9GHz, the second harmonic was 60dB down and the third better than 80dB down. Output is about 0.5dBm at 200MHz and 2.4dBm at 2GHz, back down to 1.4dBm at 3.9GHz. Spurs are about -70dBc I only bought it to use as a signal source for 3.4GHz because my Agilent runs out of puff at 3GHz. Might find a few more uses for it, but it isn't going to replace the E4421B. I might put it into a box, it is very convenient to use if it is running from a battery. Neil G4DBN
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Re: Timepod (was - Morion OCXO)
"Cross correlation" suggests mixing of the two sources and averaging (filtering) the result followed by digitisation of the baseband output. Or at least its equivalent using DSP Quadrature mixer to resolve ambighities. I've been intending to make something do that for ages- but its not high up the priority tree. I've measured such reference sources by multiplying both the test signal and the reference up to 2.5GHz, but 900Hz apart, then mixing the two signals and using a sound card to monitor the resulting 900Hz. An FFT plot shows short term stabilities and frequency offsets. 'jnt
On 3 August 2016 at 18:29, Grant Hodgson grant@... [ukmicrowaves] <ukmicrowaves@...> wrote:
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Re: WG16
mike G6TRM
toggle quoted messageShow quoted text
Hi Adrian,
I think you will find that flexible WG16 will not
work, It was not designed to be used for large
continuous movement, but mostly to counteract vibration
problems. The only way I know that truly works would be a rotatable
joint from a large system 3cm marine radar, it will require to
be on the rotational centre line of the mast, which will be another
issue to be resolved. copper water pipe is a good alternative to WG16 but the
rotating joint issues still remains..
good luck,
best regards,
Mike G6TRM
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Re: Timepod (was - Morion OCXO)
Grant Hodgson <grant@...>
The Timepod is a very high performance instrument for measuring the stability of signa lsources. It uses cross-correlation to reduce the system noise floor to very low levels. It was designed by John Miles KE5FX as a commercial product which is sold by Symmetricom.
toggle quoted messageShow quoted text
Timelab is the analysis program that does the back-end processing, also written by John and performs time, phase amd frequency analysis. The Timepod uses LTC2216 ADCs and great care was taken with the signal layout, use of low-noise regulators, signal conditioning etc. Digital data is sent to the PC for processing in Timelab, which does the FFTs, user displays etc. Timepod retails for around $5k, out of the reach of most amateurs but representing and exceptional price/performace for commercial customers. The schematic is provided in the manual if you want to roll your own! regards Grant G8UBN Quoting "Andy Talbot andy.g4jnt@gmail.com [ukmicrowaves]" <ukmicrowaves@yahoogroups.com>:
Interesting link - in a way. That 'TimePod', described as a 'Programmable
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Re: Morion OCXO
Stephen Tompsett
I'm using an HP53132 counter/timer to compare oscillators against a GPS locked rubidium reference, basically just measuring the phase difference between the oscillators under test. The software makes it easy to control the counter and acquire and analyse the collected data. Stephen Tompsett
On 3 Aug 2016 13:41, "Andy Talbot andy.g4jnt@... [ukmicrowaves]" <ukmicrowaves@...> wrote:
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