[time-nuts] Source for DC-blocking 50-ohm terminators? (Spectracom 8140)

Julien Goodwin time-nuts at studio442.com.au
Mon Jun 4 10:06:14 EDT 2018


Making my own that fits in either the mini Pomona boxes (which has
BNCs)[1] or the nice really tiny Crystek SMA housings[2] with a BNC to
SMA looks like it's probably the sensible option.

1: https://www.pomonaelectronics.com/products/boxes/boxes-with-connectors

2: http://www.crystek.com/microwave/spec-sheets/enclosure/SMA-KIT-1.3MF.pdf

On 04/06/18 22:52, Bob kb8tq wrote:
> Hi
> 
> DC blocked 50 ohm terminations are indeed a bit odd. One answer is to simply use the 
> 75 ohm version and move on. The gotcha there is that they may / may not have a block
> that works well at 10 MHz ( = the cap is to small ). The one thing *not* to do is to run the
> device with no termination on the cable. The gizmo will be perfectly happy. Your lab will
> be a mess. The coax will normally be long enough to make a great antenna at 10 MHz. 
> Leaving the end un-terminated puts it in “antenna mode”. You will have RF all over everything.
> I have a lot of experience with this specific problem …..
> 
> Bob
> 
>> On Jun 4, 2018, at 12:09 AM, Julien Goodwin <time-nuts at studio442.com.au> wrote:
>>
>> I'm looking at using a Spectracom 8140 for 10Mhz distribution, and they
>> specify using a DC-blocking 50-ohm terminator on each run.
>>
>> These seem to be odd enough that none of my usual sources have them
>> (75-ohm DC-blocking terminators yes, 50-ohm, no).
>>
>> While it's easy enough to chain a DC block and a terminator, I'd prefer
>> a single module I can more obviously label as the line termination.
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