Attitude Gyro Question: Sigma Tek 5000

[0TreeLemur]

I've obtained a Sigma Tek 5000B attitude gyro, and the connections on the back seem to be slightly different from the "stock" Mooney attitude gyro.  The photo is worth a thousand words.  What is that connection?   Is it a place vacuum source to connect another gyro in parallel?    In my a/c the original Mooney AI has a fitting there that goes to the vacuum gauge, while the other one that says "GAGE" on this figure goes to the Brittain turn coordinator (I think).  

Somebody's going to know this.    Thanks in advance.

[laytonl]

Fred, I believe that port is used to drive some autopilots.  Lee

[0TreeLemur]

Thanks Lee- I enjoyed meeting you at the Mooney fly-in in Culman last Saturday!

[0TreeLemur]

When I search for an installation manual, all that turns up is the drawing shown above.  Does anyone know of an installation manual for the Model 5000B?

[StevenL757]

Fred, it looks like your drawing above came from SigmaTek’s site here...under the “Support” section, which, sadly, is all that appears under “Installation Data and Operator’s Manuals”.

http://www.sigmatek.com/tech_info.html

Also, only the “E” and “L” series gyros will drive an autopilot...it doesn’t appear the “B” model will.   Ring their tech support folks directly, and/or your avionics guys to see if either one can get you a more detailed installation document.

Steve

[N201MKTurbo]

It depends on the model. The vacuum and filter ports move around. Yours should be marked as to which port is what.

[0TreeLemur]

2 hours ago, N201MKTurbo said:

It depends on the model. The vacuum and filter ports move around. Yours should be marked as to which port is what.

Facing the rear of the Sigma Tek 5000, as the drawing shows, the four ports are:

                  VAC

         FILTERED AIR

GAGE                     ?????

The unlabeled port is 1/4" NPT and arrived with no plug, just a hose barb fitting so it was connected to something.  On my old AI, which is the Mooney original, the connections are:

                               VAC

                    FILTERED AIR

   BRITTAIN_TC            GAGE 

I'm thinking that this fourth port is a source of suction to drive other devices.   On my a/c it seems that the three outer ports are all connected to a common plenum.  I just want verification that this is the same for the Sigma Tek 5000B.  That would mean that the 5000B is a slide-in replacement for my original gyro.

-Fred

[Marauder]

21 minutes ago, Fred₂O said:

Facing the rear of the Sigma Tek 5000, as the drawing shows, the four ports are:

                  VAC

         FILTERED AIR

GAGE                     ?????

The unlabeled port is 1/4" NPT and arrived with no plug, just a hose barb fitting so it was connected to something.  On my old AI, which is the Mooney original, the connections are:

                               VAC

                    FILTERED AIR

   BRITTAIN_TC            GAGE 

I'm thinking that this fourth port is a source of suction to drive other devices.   On my a/c it seems that the three outer ports are all connected to a common plenum.  I just want verification that this is the same for the Sigma Tek 5000B.  That would mean that the 5000B is a slide-in replacement for my original gyro.

-Fred

I believe that second port is for another vacuum source (like an electric stand-by vacuum system) if it isn't used by the AP. This drawing may help.

http://www.sigmatek.com/php/embed_pdf.php?doc=4B195

Edited January 29, 2019 by Marauder

[StevenL757]

9 hours ago, N201MKTurbo said:

It depends on the model. The vacuum and filter ports move around. Yours should be marked as to which port is what.

For vacuum and filter ports, maybe, but I'm talking about autopilot capability.  My point was that the "B" models - according to their website - are not A/P compatible/capable; whereas the "E" and "L" models are...unless I'm missing something.

[0TreeLemur]

@Marauder solved my dilemma with the drawing here:   http://www.sigmatek.com/php/embed_pdf.php?doc=4B195 .   The first drawing contained in that pdf shows that that the three ports distal from the central vacuum connection are all at common pressure of the instrument case.  My mystery port is labeled "Alternate Vacuum Port".   The port not shown on that drawing is labeled "GAGE".  Some of the models on the other drawings show an electrical connector shown where my mystery port is located at the beginning of this thread.   It all makes sense now.

In the case of my original gyro, which is I believe and Edo-Aire predecessor to Sigma Tek, the bottom two ports were connected opposite to what they were supposed to be, but they still worked because the case is a plenum.

Thanks @Marauder !!

MS+1 Mystery Solved!!!

 

[N201MKTurbo]

2 hours ago, StevenL757 said:

For vacuum and filter ports, maybe, but I'm talking about autopilot capability.  My point was that the "B" models - according to their website - are not A/P compatible/capable; whereas the "E" and "L" models are...unless I'm missing something.

Autopilot gyros have pickup coils in side and a connector. 

[DCarlton]

On 1/29/2019 at 2:44 PM, 0TreeLemur said:

@Marauder solved my dilemma with the drawing here:   http://www.sigmatek.com/php/embed_pdf.php?doc=4B195 .   The first drawing contained in that pdf shows that that the three ports distal from the central vacuum connection are all at common pressure of the instrument case.  My mystery port is labeled "Alternate Vacuum Port".   The port not shown on that drawing is labeled "GAGE".  Some of the models on the other drawings show an electrical connector shown where my mystery port is located at the beginning of this thread.   It all makes sense now.

In the case of my original gyro, which is I believe and Edo-Aire predecessor to Sigma Tek, the bottom two ports were connected opposite to what they were supposed to be, but they still worked because the case is a plenum.

Thanks @Marauder !!

MS+1 Mystery Solved!!!

 

Four years later and I’m trying to unravel this same mystery.  Lo and behold Mooneyspace comes through even when the Sigmatek site didn’t.  In my case, I believe the ALT Vac Port is being used to operate my vacuum step servo.  I’m replacing my AI with an AV30 and want to make sure I reassign the mystery line to a proper source.  When I first saw it, I thought it was a static line which made no sense!