[amsat-bb] Re: Cables for small satellites

Graham Shirville g.shirville at btinternet.com
Thu May 5 04:53:25 PDT 2011

Hi All,

Many thanks to the kind experts who kindly sent us information in repect to 
this enquiry a couple of weeks ago.

For FUNcube we have determined that the best coax for our purposes is RG178. 
The following reasons:

we are only concerned with VHF and UHF signals
flight heritage
small diameter
small minimum bend radius
suitability for a variety of connectors - we are using  MCX,  MMCX and SSMCX 
connectors on different boards (for good reasons of course)

Lessons learnt and advice received included:

RG178 should not be used outside a spacecraft where it might be exposed to 
The cables will need retaining in some way to resist viabration during 
launch - glue to board or "tie" to structure.
The connectors will also need to be glued together before flight
It may be peferable/more reliable to solder cables directly to boards for 
flight models.
All connectors are designed for a limited number of insertions. Therefore 
"saver" cable/connector assemblies should be used during most of the 
testing/verification programme.
There is a range of extra flexible semi-rigid cables available. (Thats 
sounds confused)
Like all COTS items used in space, the minimum bend radius rule of thumb - 6 
times the outer diameter - should be derated if possible.

again thanks an apologies for the delay in getting the results back out:)



A simple question this time!

What is the best coax cable to use in a cubesat? Size, flexibility/min 
existing space heritage, ease of applying connectors are our main design 
- we are only using UHF and VHF so losses are not going to be too much of a
problem hopefully..

many thanks in advance



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