Re: CDC Connectors

["Fernando J. Barbosa" <barbosa@jlab.org>]

Hi Tim,

Thanks for providing the link.

Regards,
Fernando

Tim Whitlatch wrote:
> Slava's drawings can be found at;
>
> http://www.jlab.org/Hall-D/gluex_secure/CD3_DRAWING_PACKAGE/01.DETECTOR/02.central.drift.chamber.pdf 
>
>
> Tim
> Fernando J. Barbosa wrote:
>> Hello everyone,
>>
>> I have attached a pdf describing the edge card connector from EDAC. 
>> This is similar to the one Gerard suggested but in 0.156" contact 
>> spacing. The connector part number is 307-030-500-202, which is a 30 
>> contacts on dual row with a HV rating of 1800 V AC rms,  
>> Thermoplastic Polyester insulator and $3.05. I searched for similar 
>> connectors and Sullins also has a similar one rated at 1800 V DC but 
>> with a different insulator (PPS Ryton). However, the cost for the 
>> Sullins part is five times higher at ~$15. The EDAC connector is 
>> stocked at Newark.
>>
>> Now for the assembly details which are based on Slava's drawings. 
>> Slava, I would appreciate if you could email your drawings to those 
>> on this distribution list.
>>
>> The assembly attempts to minimize the cable length from the straw to 
>> the connector:
>>
>> 1. 24 RG-174 cables are prepared as follows:
>> a. Strip both ends so that there is the center conductor for 
>> soldering, insulation of center conductor, braid and outer 
>> insulation. Each is about .125 long so there are steps (different 
>> diameters).
>> b. On the straw side, prepare as is now planned with solder ball and 
>> conductive rubber. Maybe a heat shrink piece could be applied to 
>> secure the conductive rubber cylinder and cover the shield in one step.
>> c. On the connector side, slide each of the 24 cables into a small 
>> copper plate (perhaps a bit less than .125 thick) with 24 holes and 
>> solder the shield braids at the exit of the holes. The shields will 
>> all be connected together to the shield HV and to 2 connector pins. 
>> Solder each of the 24 center conductors to the connector.
>>
>> 2. The connector has 24 pins connected as in 1.c above, the next 2 
>> adjacent pins connect to the copper plate to the shield HV, as in 1.c 
>> above. The next two pins are left unconnected and insulated or cut. 
>> the final 2 pins are soldered to a cable to attach to the endplate 
>> for grounding (ground on card is connected to endplate in this way.
>>
>> 3. The back side (soldered connections) is sealed with the proper 
>> viscosity sealer and with low out-gassing characteristics (no 
>> silicone here). The finished part forms the connector assembly.
>>
>> 4. Connect all the cables from all the cable assemblies to the straws 
>> and endplate (grounds).
>>
>> 5. Attach dummy boards with straps to the edge card connectors on 
>> each of the cable assemblies.
>>
>> 6. Position the gas plenum Plexiglass cover and feed all the straps 
>> through their respective holes on the Plexiglass cover. Slide this 
>> cover while pulling or straightening  the straps until the cover 
>> touches the connectors.  Attach the connectors with screws, washer 
>> and neoprene seal washer.
>>
>> 7. Rotate CDC so that connector side is at top.
>>
>> 8. Apply sealer (see 3 above) around each of the 
>> connectors/plexiglass holes.
>>
>> In this way, we only need a short distance between the straws and the 
>> gas plenum cover. This is not very elaborate but  I can provide a 
>> drawing if necessary to better explain this technique. Please note 
>> that if one of the wires in the straws brakes and shorts tripping the 
>> HV, all the 24 channels in the group will be off. This is required 
>> because the shields are also at HV and the RG-174 is not rated for 
>> this level of HV. So, this is inherently safe.
>>
>> There will also be an aluminum plate or aluminized mylar cover over 
>> the whole gas plenum and grounded for shielding.
>>
>> Please provide feedback so we can finish the design of the HVB PCB. 
>> The HVB PCB will have the HV distribution network, the connections to 
>> the preamp card connector, grounding, etc. The preamp card, as in the 
>> FDC, is removable from the HVB.
>>
>> Regards,
>> Fernando
begin:vcard
fn:Fernando J. Barbosa
n:Barbosa;Fernando J.
org:Jefferson Lab
adr:Suite #10, 12B3;;12000 Jefferson Ave.;Newport News;VA;23606;USA
tel;work:757-269-7433
version:2.1
end:vcard