Microwave, RF & LF Signal Sources & Sensor Systems

Spectral Line Systems Ltd

Research, Custom Design & Manufacture


Ordering Parts
Typical Items Machined In-House
Turning prototype precision coaxial parts
Beech Cabinets for “Curikela” Kits

Manufacturing starts with Procurement, often one of the most time-consuming stages of the job. Working from the components lists, parts lists and schedules of fasteners forming part of the drawing set, the various items required are ordered and consigned to a production store as they are received. Some commonly used items may be drawn from general stock and transferred to the production store, provided that all parts in the store are covered by a supplier's Certificate of Conformance.


In the case of single-sourced components, long lead items or devices suspected of having a short market lifetime, a generous spares allowance is made. Where such items are expensive the situation is discussed with the customer and a spares holding specified in the contract for warranty repair purposes. Sometimes it is necessary to have a component specially developed for the job by another company, and here Spectral Line Systems Ltd has extensive experience of preparing suitable sub-contracts. In low phase noise work reliance is often made on the noise performance of some component even although this parameter is unspecified in the data sheet. In such cases it is necessary to measure component batches for added phase noise and select for production.


Machined parts are either procured outside or manufactured in house according to quantity. Our in-house machining facilities although good are more on the scale of a tool room than a production machine shop. We have two such facilities similarly equipped, one in our Tarbert works and one in our South of Scotland base, the latter being used mainly for R & D prototypes. The Tarbert workshop produces small production batches of parts, and is invaluable when faced with excessive lead times quoted by outside machining companies.


We machine mainly in aluminium alloy, copper, brass and plastics, and are capable of manufacturing any mechanical part or assembly used in our designs, including waveguide components as well as items such as housings and baseplates. Our range of machine tools varies from CNC mills down to a minute watchmaker's lathe for work on small coaxial parts and semi rigid cables.


Unusually for a microwave and RF engineering company, we also have a substantial woodworking shop in which we manufacture all our own packing cases as well as high quality cabinets and enclosures for our "Curikela" range of RF constructional kits, and for some items of production test gear which do not require electromagnetic screening by the outer protective case.


Assembly & Test

Final Assembly of a 15 GHz Source
PCB Inspection Prior to Installation
Final Test Benches for a Major Contract
Completed Sub Units Inspected, Sealed and Labelled

The small batch sizes associated with our business result in most electronic assembly and test being performed manually. All components and pcb finishes are now lead-free, although tin/lead solders are still employed on some RoHS exempt work. Great care is taken to segregate the two types of soldering operation. The need for good ground planes in microwave and RF work gives rise to a high degree of heat sinking during soldering, making it frequently necessary to employ background heat, particularly in the lead free-case.


Anti-static precautions are taken in all stages of electronic assembly, and we consider it good design practice to include high-valued resistors to ground on all pcb input and output lines.


All assembled pcb's are fully inspected under the microscope before being installed in housings and powered up. We have found that virtually all potential faults due to assembly problems can be identified and rectified at this stage. Following final assembly and test, all sub-units are visually inspected once more before the units are sealed.


All production test gear is maintained in good order and kept in calibration. As with R & D instrumentation, we only buy new or refurbished items directly from the manufacturer, and use the manufacturers' calibration facilities wherever possible for all microwave and RF instruments.


In many production contracts, particularly for more complex sources and sub-systems, considerable effort is put into building special test gear for both sub-unit and final test to ensure production proceeds as smoothly and quickly as possible.


Following test, all sub-units and final assemblies are inspected, sealed and labelled, the label carrying the signatures of the persons responsible for test and inspection.


Production test gear requiring RF modules can often be assembled quickly using our "Curikela" range of RF constructional kits.