Date   

Re: COAXIAL CABLE LMR400

Conrad, PA5Y
 

Over here there is lots of RFS cable and hardly any Commscope. LMR cables are far too expensive.  I have loops of SCF12-50J and also run it up the tower, so far so good. Including VAT both LCF12-50 and SCF12-50 is 3.70 EUR per meter and Spinner N types are 11.70 EUR each, 7/16 about the same. This is genuine cable and high quality. I no longer use any amateur cables as it is 2-3 times more expensive and about 1/4 as good. As I have 360 deg of good take off I rotate my antennas a lot and I am quite active. Therefore I believe that these cables are up to the task.

Regards

Conrad PA5Y


From: UKMicrowaves@groups.io <UKMicrowaves@groups.io> on behalf of John Lemay via groups.io <john@...>
Sent: 09 May 2021 09:56
To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] COAXIAL CABLE LMR400
 
Martin

LMR-400 is not very flexible and whilst it will be fine for running up
the tower, it is less suitable for a rotator loop - unless you form it
in a helix of a couple of turns. FWIW I run LDF4-50 up the tower to the
head unit and then use flexible cables at the rotator.

Reliable names to look out for are Times Microwave and Commscope. As
others have said, you may or may not get good performance from the many
clones that are available. DX Shop is one UK source.

Yes, you will need connectors which are specific to LMR-400.

Regards

John G4ZTR

On 2021-05-08 21:26, Martin wrote:
> Could I ask for some information on LMR 400 coaxial cable from anyone
> who has used it and how it turns out in practise.
> I gather from what I have read, that its good quality and fairly low
> loss when compared with the other 10 mm approx. diameter cables. I am
> looking for something for use on 23 cms and will be using half inch
> LDF4-50A for the main run from shack to tower base and something more
> flexible from there on, around say another 45 feet. I will be running
> an LNA at the top and close to the Yagi.
> I cannot see that it is available from the main amateur radio dealers
> and there is one commercial supplier who will only provide it in 100 m
> drums.  I am happy to invest a in this quantity, (for other purposes
> and bands) but not until I know more about the cable itself. Does it
> require special N series plugs and how flexible is it etc? Its
> available on eBay I think but again, reading seems to suggest there is
> some dubious quality cable being sold which is fake?
>
>
> Links:
> ------
> [1] https://groups.io/g/UKMicrowaves/message/62381
> [2] https://groups.io/mt/82686040/239367
> [3] https://groups.io/g/UKMicrowaves/post
> [4] https://groups.io/g/UKMicrowaves/editsub/239367
> [5]
> https://groups.io/g/UKMicrowaves/leave/3272144/239367/1480192407/xyzzy






Re: Microwave dish size and shape versus frequency question

KENT BRITAIN
 

Glad it helped.   Kent WA5VJB/2E0VAA/G8EMY

Yes, I know, a G8, but it is a full license.   Really wanted that G Call! hihi

American hams have no idea what the 8 means.



On Sunday, May 9, 2021, 11:35:23 AM CDT, Chris Wilson <chris@...> wrote:


Hello Kent,

Friday, May 7, 2021

Thanks for the reply Kent, appreciated and helpful.


Best regards,
Chris    2E0ILY      mailto:chris@...


KB> Interesting way to think about it,  But the focal points for the
KB> 2.4 GHz and 10 GHz waves are slightly different
KB> since 2.4 GHz waves cannot become an infinitesimal point.    Of
KB> course 10 GHz wave cannot either.
KB> And 2.4 GHz feeds and 10 GHz feeds will have different phase centers.


KB> In the practical world the points are pretty close and just make
KB> your feed support adjustable and move it
KB> in and out a bit for best signal levels.  I have tested hundreds
KB> of dishes on the antenna range and the feed
KB> usually ends up a bit closer to the dish than the calculated focal point.


KB> Frequency limits on the size of the dish.


KB> The dish needs to be a least 5 wavelengths across to bring the waves to a focus.


KB>                  For 23 cm this would be about a 1 Meter dish.    10 wavelengths is preferred.


KB> Upper frequency is determined by the surface accuracy of the dish surface.


KB>                  Most commercial dishes are good to 24+ GHz


KB> The offset dish can be more difficult to work with since the feed point is not as obvious and
KB> pointing can be more difficult.  But it gets the feed structure out of the beam.


KB> Good luck with your project, Kent





KB>   
KB> 
KB>   
KB>                      On Friday, May 7, 2021, 08:28:18 AM CDT,
KB> Chris Wilson <chris@...> wrote:   

KB> 

KB> 




KB>  07/05/2021 14:20



KB> Absolute newbie question coming...



KB> I saw a big microwave dish advertised on Ebay and then by
KB> coincidence saw this advert mentioned on a UK Satellites forum. I
KB> am getting started in amateur radio satellite communications,
KB> initially via a 1.8 meter PF dish and the QO-100 satellite using
KB> SSB and hopefully later, ATV signals.



KB> The up link is on 2.4 GHz and someone extolling the magnificence
KB> of the Ebay dish was shot down by someone saying it may well be no
KB> use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.



KB> This surprised me, I naively thought a dish was a dish, with
KB> prime or offset focus, but now thinking deeper I recall seeing
KB> very small, but seemingly deep versus diameter 10GHz dishes on tripods.



KB> So may I ask, how is the size / shape of a microwave dish related
KB> to its intended frequency usage please? Thanks.



KB> This is the link to the dish in question:



KB> https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649









Re: Microwave dish size and shape versus frequency question

Chris Wilson
 

Hello Kent,

Friday, May 7, 2021

Thanks for the reply Kent, appreciated and helpful.


Best regards,
Chris 2E0ILY mailto:chris@chriswilson.tv


KB> Interesting way to think about it, But the focal points for the
KB> 2.4 GHz and 10 GHz waves are slightly different
KB> since 2.4 GHz waves cannot become an infinitesimal point. Of
KB> course 10 GHz wave cannot either.
KB> And 2.4 GHz feeds and 10 GHz feeds will have different phase centers.


KB> In the practical world the points are pretty close and just make
KB> your feed support adjustable and move it
KB> in and out a bit for best signal levels. I have tested hundreds
KB> of dishes on the antenna range and the feed
KB> usually ends up a bit closer to the dish than the calculated focal point.


KB> Frequency limits on the size of the dish.


KB> The dish needs to be a least 5 wavelengths across to bring the waves to a focus.


KB> For 23 cm this would be about a 1 Meter dish. 10 wavelengths is preferred.


KB> Upper frequency is determined by the surface accuracy of the dish surface.


KB> Most commercial dishes are good to 24+ GHz


KB> The offset dish can be more difficult to work with since the feed point is not as obvious and
KB> pointing can be more difficult. But it gets the feed structure out of the beam.


KB> Good luck with your project, Kent





KB>
KB>
KB>
KB> On Friday, May 7, 2021, 08:28:18 AM CDT,
KB> Chris Wilson <chris@chriswilson.tv> wrote:

KB>

KB>




KB> 07/05/2021 14:20



KB> Absolute newbie question coming...



KB> I saw a big microwave dish advertised on Ebay and then by
KB> coincidence saw this advert mentioned on a UK Satellites forum. I
KB> am getting started in amateur radio satellite communications,
KB> initially via a 1.8 meter PF dish and the QO-100 satellite using
KB> SSB and hopefully later, ATV signals.



KB> The up link is on 2.4 GHz and someone extolling the magnificence
KB> of the Ebay dish was shot down by someone saying it may well be no
KB> use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.



KB> This surprised me, I naively thought a dish was a dish, with
KB> prime or offset focus, but now thinking deeper I recall seeing
KB> very small, but seemingly deep versus diameter 10GHz dishes on tripods.



KB> So may I ask, how is the size / shape of a microwave dish related
KB> to its intended frequency usage please? Thanks.



KB> This is the link to the dish in question:



KB> https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649


Re: Microwave dish size and shape versus frequency question

Chris Wilson
 

Hello Neil,

Friday, May 7, 2021

Thanks very much to all who replied, here and directly. A special thanks to Neil for the very detailed yet easy to follow explanation, I appreciate your time doing that :)

Just for completeness, if someone bought the dish in the Ebay advert at

https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

Is there a risk it might not work at all effectively on 2.4GHz TX or for 10.5GHz RX? That is what was stated on the Sats UK forum, and no one seemed to query the statement. All the best and thanks again 2E0ILY (Chris in Shropshire).


Best regards,
Chris 2E0ILY mailto:chris@chriswilson.tv


NSG> Hi Chris, so long as a dish is large enough relative to a
NSG> wavelength to avoid diffraction loss at the frequency chosen, and
NSG> the surface irregularities are small enough relative to a
NSG> wavelength to prevent loss from phase errors, *and you can
NSG> illuminate it fully without much spillover*, then the depth
NSG> of the dish does not matter much.

NSG> Usual vague rule of thumb is that the dish diameter needs to be
NSG> at least 10 times the wavelength and surface errors need to be
NSG> about a tenth of the wavelength across the entire surface. As a
NSG> dish gets deeper, it gets harder to illuminate the surface unless
NSG> you use a subreflector, so most PF dishes have a focal length
NSG> about 0.3 to 0.5 of their diameter. Offset dishes tend to be
NSG> shallower, perhaps 0.5 to 0.7 f/d ratio.
NSG>
NSG>
NSG> Subreflectors need to be a minimum of 8-10 wavelengths, so a
NSG> very deep dish 2m wide at 13cm would need a subreflector
NSG> over a metre in diameter, and that would block the dish
NSG> very seriously, so deep dishes under f/d 0.3 are generally
NSG> only used where the diameter is 40 or more times the
NSG> wavelength. With an f/d 0.25 dish, the focus is in the
NSG> same plane as the edges of the dish, so the feed has to be
NSG> able to illuminate the edge at 90 degrees to the axis, which is
NSG> challenging. Worse, you usually set the illumination so it is
NSG> about 10-12 dB down at the edge of the dish to get best
NSG> efficiency with least spillover, but in an f/d 0.25 dish,
NSG> the edge is twice as far from the focus as the centre, to
NSG> there is an additional 6dB of taper added (space
NSG> attenuation) and the feed needs to be only 4-6 dB down at 90 degrees.
NSG>
NSG>
NSG> Those 1.8 dishes are probably OK at C-band, and might even work
NSG> at 12 GHz. Definitely OK for 2.4 but very very sharp and
NSG> potentially too gainy at 10 GHz if the surface is accurate. If
NSG> it isn't very accurate, the beam will be less sharp and more useable.
NSG>
NSG>
NSG> For narrowband use on QO100, 800 mW to a 95 cm dish gets me to
NSG> the reference beacon level, so you would probably only need 125
NSG> mW to get to the reference level on narrowband to the 1.8m
NSG> dish. For TV use, obviously you need to be running more
NSG> power, but that giant dish will mean you can under-run a
NSG> big PA to get minimum spectral regrowth and a super clean signal.
NSG>
NSG> I reckon a 1.0 to 1.2m offset dish is about the sweet spot for
NSG> QO100 unless you have loads of space and something very solid to bolt a 1.8m pf dish down to.
NSG>
NSG> Neil G4DBN
NSG>
NSG>

NSG>
NSG>
NSG> On 07/05/2021 14:27, Chris Wilson wrote:
NSG>
NSG>


NSG> 07/05/2021 14:20

NSG> Absolute newbie question coming...

NSG> I saw a big microwave dish advertised on Ebay and then by
NSG> coincidence saw this advert mentioned on a UK Satellites forum. I
NSG> am getting started in amateur radio satellite communications,
NSG> initially via a 1.8 meter PF dish and the QO-100 satellite using
NSG> SSB and hopefully later, ATV signals.

NSG> The up link is on 2.4 GHz and someone extolling the magnificence
NSG> of the Ebay dish was shot down by someone saying it may well be
NSG> no use at all for 2.4 GHz uplink., for example, and was probably made for a specific purpose.

NSG> This surprised me, I naively thought a dish was a dish, with
NSG> prime or offset focus, but now thinking deeper I recall seeing
NSG> very small, but seemingly deep versus diameter 10GHz dishes on tripods.

NSG> So may I ask, how is the size / shape of a microwave dish
NSG> related to its intended frequency usage please? Thanks.

NSG> This is the link to the dish in question:

NSG> https://www.ebay.co.uk/itm/164502970358?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649


NSG>
NSG>


Re: wtKST not talking to Airscout

Pete - GM4BYF
 

Thanks Brian  - but it is not that. Doing some more investigation.

73
Pete GM4BYF

On 09/05/21 15:47, Brian Howie GM4DIJ wrote:
On 09/05/2021 14:18, Pete - GM4BYF via groups.io wrote:
Trying to set up on another P.C. When left clicking on the correct box for a callsign on wtKST to get the correct map up on Airscout, nothing happens. On my current laptop this is working well.

Any help gratefully received please.
Options Airplane Scatter , remember to tick Activate. Fools me when I have to refresh or re-install. The other problem I sometimes have is where the "tiles" are stored, but if airscout works "standalone" it's not that.

Brian GM4DIJ
--
vry 73
Pete GM4BYF


Re: wtKST not talking to Airscout

Brian Howie GM4DIJ
 

On 09/05/2021 14:18, Pete - GM4BYF via groups.io wrote:
Trying to set up on another P.C. When left clicking on the correct box for a callsign on wtKST to get the correct map up on Airscout, nothing happens. On my current laptop this is working well.
Any help gratefully received please.
Options Airplane Scatter , remember to tick Activate. Fools me when I have to refresh or re-install. The other problem I sometimes have is where the "tiles" are stored, but if airscout works "standalone" it's not that.

Brian GM4DIJ

--
Brian


wtKST not talking to Airscout

Pete - GM4BYF
 

Trying to set up on another P.C. When left clicking on the correct box for a callsign on wtKST to get the correct map up on Airscout, nothing happens. On my current laptop this is working well.

Any help gratefully received please.

--
73
Pete GM4BYF



--
vry 73
Pete GM4BYF


Re: COAXIAL CABLE LMR400

Pete - GM4BYF
 

I am using Unispectra S400 for connection round a rotator. No problems so far. 0.167 dB loss per metre.

73
Pete GM4BYF
On 08/05/21 21:26, Martin wrote:

Could I ask for some information on LMR 400 coaxial cable from anyone who has used it and how it turns out in practise. 
I gather from what I have read, that its good quality and fairly low loss when compared with the other 10 mm approx. diameter cables. I am looking for something for use on 23 cms and will be using half inch LDF4-50A for the main run from shack to tower base and something more flexible from there on, around say another 45 feet. I will be running an LNA at the top and close to the Yagi.
I cannot see that it is available from the main amateur radio dealers and there is one commercial supplier who will only provide it in 100 m drums.  I am happy to invest a in this quantity, (for other purposes and bands) but not until I know more about the cable itself. Does it require special N series plugs and how flexible is it etc? Its available on eBay I think but again, reading seems to suggest there is some dubious quality cable being sold which is fake?      

--
vry 73
Pete GM4BYF


Re: QRP PA devices for 10 GHz

Oguzhan Kayhan
 

Hello
It would be nice to have any pcb designs to be able to use it specially with the transverters that Neil is preparing
I would definitely love to get one


On Sun, May 9, 2021 at 1:24 PM Neil Smith G4DBN <neil@...> wrote:
I'm going to try a PCB with 0.3 mm PTH in a tight pattern, solder it to
the spreader first, let it cool, then use a stencil to fill the holes
with paste and put the whole assembly in my oven for reflow. Another
approach is to get the PCB fab to fit the devices, then  use low temp
solder to fix the PCB to the spreader. If the two-step process isn't
successful, I'll go one-step for the while thing.  When that fails, I'll
go back to silver epoxy.

I haven't decided what connectors to use yet.  I have some tab-launch
SMAs rated to 27 GHz, but I think I prefer the idea of these:
https://www.digikey.co.uk/product-detail/en/cinch-connectivity-solutions-johnson/142-0761-811/J798-ND/673171
which are cheaper than the Amphenol SV Microwave versions.

I wonder if using GCPW lines for the RF connections might mean I can use
solder resist over the lines so I can solder the connectors at the same
time as the components. I'll have a chat to my friendly neighbourhood
CPWG expert. Doubtless everyone will say I will get away with ENIG or
HASL on FR4, but where's the fun in that?  I know there are others
working on designs using the same little chip and they are certain to be
better than my feeble attempts.

I have other stuff to get finished first though. LOTS of other stuff.

Neil G4DBN

On 09/05/2021 01:13, Greg - ZL3IX wrote:
> Looks like just the sort of thing I'm looking for, Neil, although, as
> you say, dissipating the heat will be a serious challenge. I'm not
> sure how to go about that, and will have to do some research on the
> thermal resistance of vias. I guess it would need a copper heat
> spreader, which would need to be pre-heated before attempting to
> solder the device. That's all new territory for me! Luckily one
> appears to be able to use the internal reference diode as a temp
> sensor, so at least the device can be shut down when too hot.







--
73
de TA2NC


Re: COAXIAL CABLE LMR400

Reg Woolley
 

I agree many use FSJ 4 50.however that has a very fragile outer jacket and can easily be rubbed away.

Reg g8vhi 



Sent from my Samsung Galaxy S10e - Powered by Three


-------- Original message --------
From: "alwyn.seeds1" <a.seeds@...>
Date: 09/05/2021 10:28 (GMT+00:00)
To: "UK Microwaves groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] COAXIAL CABLE LMR400

Dear Martin,

If you need flexibility for rotator loops, then LMR400-UF rather than LMR400 is what you need.

There are many clones, some good, some bad, as others have commented. Foam dielectric cables are not easy to make as fluctuations in foam density in extrusion cause fluctuations in characteristic impedance. Look at the swept frequency return loss, if the manufacturer dares publish it. Of course some manufacturers publish data but the actual cable performance falls short of what is published.

I find that LMR400-UF works quite well for rotator loops, provided these are designed with no sharp bends- the foam in LMR400-UF is denser than in some of the alternative cables, so that displacement of the inner conductor with repeated flexure is less of a problem. I have loops that are getting on for 10 years old and still work fine at frequencies up to 1298 MHz.

Times Microwave, which is a subsidiary of Commscope, also have a MIL-SPEC flexible tactical cable series, that has a special tape shielding which is more suitable for repeated flexure than the bonded foil used in LMR400-UF- I am awaiting pricing details for this. It will probably be quite expensive as conductors are silver plated, construction is complex plus there are the extra quality control costs to retain a MIL-SPEC approval.

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Re: QRP PA devices for 10 GHz

Neil Smith G4DBN
 

I'm going to try a PCB with 0.3 mm PTH in a tight pattern, solder it to the spreader first, let it cool, then use a stencil to fill the holes with paste and put the whole assembly in my oven for reflow. Another approach is to get the PCB fab to fit the devices, then  use low temp solder to fix the PCB to the spreader. If the two-step process isn't successful, I'll go one-step for the while thing.  When that fails, I'll go back to silver epoxy.

I haven't decided what connectors to use yet.  I have some tab-launch SMAs rated to 27 GHz, but I think I prefer the idea of these: https://www.digikey.co.uk/product-detail/en/cinch-connectivity-solutions-johnson/142-0761-811/J798-ND/673171 which are cheaper than the Amphenol SV Microwave versions.

I wonder if using GCPW lines for the RF connections might mean I can use solder resist over the lines so I can solder the connectors at the same time as the components. I'll have a chat to my friendly neighbourhood CPWG expert. Doubtless everyone will say I will get away with ENIG or HASL on FR4, but where's the fun in that?  I know there are others working on designs using the same little chip and they are certain to be better than my feeble attempts.

I have other stuff to get finished first though. LOTS of other stuff.

Neil G4DBN

On 09/05/2021 01:13, Greg - ZL3IX wrote:
Looks like just the sort of thing I'm looking for, Neil, although, as you say, dissipating the heat will be a serious challenge. I'm not sure how to go about that, and will have to do some research on the thermal resistance of vias. I guess it would need a copper heat spreader, which would need to be pre-heated before attempting to solder the device. That's all new territory for me! Luckily one appears to be able to use the internal reference diode as a temp sensor, so at least the device can be shut down when too hot.


Re: 10 GHz 35W GaN PA devices arrived

Neil Smith G4DBN
 

For the first test, I will make a new version of the one I designed for the CMPA801B025. I have many other projects in flight, so I don't expect to have a working version for several months.

Neil G4DBN

On 09/05/2021 09:15, Mugurel via groups.io wrote:
Which pcb do you intend to use? The one in the datasheet?


Re: COAXIAL CABLE LMR400

alwyn.seeds1
 

Dear Martin,

If you need flexibility for rotator loops, then LMR400-UF rather than LMR400 is what you need.

There are many clones, some good, some bad, as others have commented. Foam dielectric cables are not easy to make as fluctuations in foam density in extrusion cause fluctuations in characteristic impedance. Look at the swept frequency return loss, if the manufacturer dares publish it. Of course some manufacturers publish data but the actual cable performance falls short of what is published.

I find that LMR400-UF works quite well for rotator loops, provided these are designed with no sharp bends- the foam in LMR400-UF is denser than in some of the alternative cables, so that displacement of the inner conductor with repeated flexure is less of a problem. I have loops that are getting on for 10 years old and still work fine at frequencies up to 1298 MHz.

Times Microwave, which is a subsidiary of Commscope, also have a MIL-SPEC flexible tactical cable series, that has a special tape shielding which is more suitable for repeated flexure than the bonded foil used in LMR400-UF- I am awaiting pricing details for this. It will probably be quite expensive as conductors are silver plated, construction is complex plus there are the extra quality control costs to retain a MIL-SPEC approval.

Regards,

Alwyn G8DOH
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Re: COAXIAL CABLE LMR400

ian hope (2E0IJH)
 

Yes there are some Poor clones, But I can safely state the clones from Wifi Antennas HDF 400 and the Clones from CCS LLA400, work well apear very similar in construction to LMR400 (TIMES) and have survived Contest Use.
Works out about £1 a meter for clones, from these sources, So is almost throw away feeder if damaged.
 
Ian
M5IJH

 
 
Sent: Sunday, May 09, 2021 at 8:56 AM
From: "John Lemay" <john@...>
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] COAXIAL CABLE LMR400
Martin

LMR-400 is not very flexible and whilst it will be fine for running up
the tower, it is less suitable for a rotator loop - unless you form it
in a helix of a couple of turns. FWIW I run LDF4-50 up the tower to the
head unit and then use flexible cables at the rotator.

Reliable names to look out for are Times Microwave and Commscope. As
others have said, you may or may not get good performance from the many
clones that are available. DX Shop is one UK source.

Yes, you will need connectors which are specific to LMR-400.

Regards

John G4ZTR

On 2021-05-08 21:26, Martin wrote:
> Could I ask for some information on LMR 400 coaxial cable from anyone
> who has used it and how it turns out in practise.
> I gather from what I have read, that its good quality and fairly low
> loss when compared with the other 10 mm approx. diameter cables. I am
> looking for something for use on 23 cms and will be using half inch
> LDF4-50A for the main run from shack to tower base and something more
> flexible from there on, around say another 45 feet. I will be running
> an LNA at the top and close to the Yagi.
> I cannot see that it is available from the main amateur radio dealers
> and there is one commercial supplier who will only provide it in 100 m
> drums. I am happy to invest a in this quantity, (for other purposes
> and bands) but not until I know more about the cable itself. Does it
> require special N series plugs and how flexible is it etc? Its
> available on eBay I think but again, reading seems to suggest there is
> some dubious quality cable being sold which is fake?
>
>
> Links:
> ------
> [1] https://groups.io/g/UKMicrowaves/message/62381
> [2] https://groups.io/mt/82686040/239367
> [3] https://groups.io/g/UKMicrowaves/post
> [4] https://groups.io/g/UKMicrowaves/editsub/239367
> [5]
> https://groups.io/g/UKMicrowaves/leave/3272144/239367/1480192407/xyzzy




 


Re: 10 GHz 35W GaN PA devices arrived

Mihai, YO8RHM
 

Which pcb do you intend to use? The one in the datasheet?

Mihai YO8RHM


Re: COAXIAL CABLE LMR400

Dave G6HEF
 

Hi Martin,

I have recently installed LDF4-50 and used CNT-400, the Commscope equivalent of LMR400, for rotator loops. All available Through DX shop, who supply connectors and will fit at no extra cost if you are confident of the lengths you require.

I know lower cost connectors are available and M0MAT is a go-to, although the official connectors are just that little bit better. Whether or not the extra costs of the official ones justifies the extra costs are a
matter of personal choice.

I spent a lot of time thinking about how to engineer my installation and to be honest only time will tell how long the cables will withstand the flexing. I suspect there will still be lessons learnt at this QTH!

Hope that helps

Dave
G6HEF


Re: COAXIAL CABLE LMR400

John Lemay
 

Martin

LMR-400 is not very flexible and whilst it will be fine for running up the tower, it is less suitable for a rotator loop - unless you form it in a helix of a couple of turns. FWIW I run LDF4-50 up the tower to the head unit and then use flexible cables at the rotator.

Reliable names to look out for are Times Microwave and Commscope. As others have said, you may or may not get good performance from the many clones that are available. DX Shop is one UK source.

Yes, you will need connectors which are specific to LMR-400.

Regards

John G4ZTR

On 2021-05-08 21:26, Martin wrote:
Could I ask for some information on LMR 400 coaxial cable from anyone
who has used it and how it turns out in practise.
I gather from what I have read, that its good quality and fairly low
loss when compared with the other 10 mm approx. diameter cables. I am
looking for something for use on 23 cms and will be using half inch
LDF4-50A for the main run from shack to tower base and something more
flexible from there on, around say another 45 feet. I will be running
an LNA at the top and close to the Yagi.
I cannot see that it is available from the main amateur radio dealers
and there is one commercial supplier who will only provide it in 100 m
drums. I am happy to invest a in this quantity, (for other purposes
and bands) but not until I know more about the cable itself. Does it
require special N series plugs and how flexible is it etc? Its
available on eBay I think but again, reading seems to suggest there is
some dubious quality cable being sold which is fake?
Links:
------
[1] https://groups.io/g/UKMicrowaves/message/62381
[2] https://groups.io/mt/82686040/239367
[3] https://groups.io/g/UKMicrowaves/post
[4] https://groups.io/g/UKMicrowaves/editsub/239367
[5] https://groups.io/g/UKMicrowaves/leave/3272144/239367/1480192407/xyzzy


Re: QRP PA devices for 10 GHz

Greg - ZL3IX
 

Looks like just the sort of thing I'm looking for, Neil, although, as you say, dissipating the heat will be a serious challenge. I'm not sure how to go about that, and will have to do some research on the thermal resistance of vias. I guess it would need a copper heat spreader, which would need to be pre-heated before attempting to solder the device. That's all new territory for me! Luckily one appears to be able to use the internal reference diode as a temp sensor, so at least the device can be shut down when too hot.


Re: COAXIAL CABLE LMR400

ian hope (2E0IJH)
 

We use drums and drums of a Clone from WIFI antennas, it uses slightly larger centre pin than Rg213, we buy plugs from M0MAT on ebay, 
 
https://www.wifi-antennas.co.uk/hdf400-coaxial-cable-100m-drum
 
It is quite stiff, but not as bad as LDF, you can a flexible version for rotator loops
 
Hope that helps 
 
Ian
M5IJH

 
 
Sent: Saturday, May 08, 2021 at 9:26 PM
From: "Martin" <gw3xjq@...>
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] COAXIAL CABLE LMR400
Could I ask for some information on LMR 400 coaxial cable from anyone who has used it and how it turns out in practise. 
I gather from what I have read, that its good quality and fairly low loss when compared with the other 10 mm approx. diameter cables. I am looking for something for use on 23 cms and will be using half inch LDF4-50A for the main run from shack to tower base and something more flexible from there on, around say another 45 feet. I will be running an LNA at the top and close to the Yagi.
I cannot see that it is available from the main amateur radio dealers and there is one commercial supplier who will only provide it in 100 m drums.  I am happy to invest a in this quantity, (for other purposes and bands) but not until I know more about the cable itself. Does it require special N series plugs and how flexible is it etc? Its available on eBay I think but again, reading seems to suggest there is some dubious quality cable being sold which is fake?      


Re: COAXIAL CABLE LMR400

John Quarmby
 

There are a lot of clones around, some better than others, in my experience it is best to avoid eBay, having encountered a clone where the aluminium shield did not enclose the whole circumference of the dielectric. If you are including a turning loop at the top of the tower then go for LMR400UF which has a stranded copper inner conductor and will last longer, but it does have slightly higher loss.

I have used Gigatronix to make up cables with crimp connectors and suitable strain relief, using their LBC400ExtraFlex equivalent. After 6 years I am just about to replace one of the masthead cables as the inner of the N socket at the top is now badly worn from changing antennas every week, all their other coax jumpers up there are still going strong.

They have a useful ordering tool where you can try various connector and cable options:

https://www.gigatronix.co.uk/cabulator/coaxial/cable-type

73

John G3XDY

On 08/05/2021 20:26, Martin wrote:
Could I ask for some information on LMR 400 coaxial cable from anyone who has used it and how it turns out in practise. 
I gather from what I have read, that its good quality and fairly low loss when compared with the other 10 mm approx. diameter cables. I am looking for something for use on 23 cms and will be using half inch LDF4-50A for the main run from shack to tower base and something more flexible from there on, around say another 45 feet. I will be running an LNA at the top and close to the Yagi.
I cannot see that it is available from the main amateur radio dealers and there is one commercial supplier who will only provide it in 100 m drums.  I am happy to invest a in this quantity, (for other purposes and bands) but not until I know more about the cable itself. Does it require special N series plugs and how flexible is it etc? Its available on eBay I think but again, reading seems to suggest there is some dubious quality cable being sold which is fake?      

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