Re: CDC Connectors

[Tim Whitlatch <whitey@jlab.org>]

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:Timothy Whitlatch, PE
n:Whitlatch;Timothy
tel;work:757-269-5087
tel;fax:757-269-5279
version:2.1
end:vcard