[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Terry's DRSSTC

Original poster: "Mike" <induction@xxxxxxxxxxx>

Hi Terry,
Yes the HFBR series are nice. I've been using the analog 125 Mhz units in 2 optical bands here on the plasma frequency receivers. They seem to make a good product, meeting spec and then some. Lately been using a PMT and 72 mm 427.8 nm filter as well. You would get that spectra from a TC ionizing the N2 in air. As I remember on the data sheets (PDF files) they speak of inverted outputs on some of the models, have a bunch of analog and digital units here.

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, January 08, 2005 7:32 PM
Subject: Terry's DRSSTC

Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>


Lots of busy work these days but it is getting there...

I have the fiber-optic link working and got the current measurement figured out now:


The fiber optic link works perfectly but it was unexpectedly inverted:



No problem since I have extra inverter gates... I did switch to Agilent HFBR-2412T receivers since they have a perfect open collector digital output with no fuss...

The analog and digital current signals are fine be a bit delayed:



Seems the CTs have about 400nS of lag. Have to work on that... I used 1N5819s in series with 4.7V 5W Zeners. The capacitance of the Zenors acts like nice rail power supplies and charges very fast:


That eliminates a lot of silly circuitry while giving super fast low-Z signals. A simple resistor and 1N4148 clips the negative side on the controller to feed the digital stuff:


We are always asking about what to use as RF and AC ground. We like to hook them together but we don't want the RF to get into the AC grounding... I really like the blocking inductor for that:


Mine is 7.5uH now:


Just a simple 10 turn inductor on a Delrin form. At 60 Hz AC its resistance is only 0.003 ohms allowing the AC ground to keep everything safe. But at say 100kHz it's resistance is 5 ohms so RF currents should be pushed into the RF grounding and not the AC grounding.

The protection board gets here monday so that will be interesting to see how badly I screwed that all up :o))


Mostly testing circuits these days...