Whats this Weird Circuit Symbol?

I have no idea what it is but I did find this:
http://www.harrykrantz.com/catalog.php?pid=RN4004 if that's any help at all.

 

Without a datasheet that's a real problem. Though if you had a schematic it might be possible to work out what the part does and work out a replacement that way.

 

Just seeing the symbol, I think we could guess some things:

1. The symbol resembles a Symmetrical JFET (in contrast to an Asymmetrical one). Probably the polarity between Source and Drain doesn't matter. The arrows might just be a way to highlight this feature.
2. The component has the Source marked out. It probably shows the pole where the control voltage of the Gate is referenced.
3. The full line between Drain and Source could indicate a Depletion type FET, which means it would lead current when Vgs=0V
4. The Gate line shows a type of MOSFET with isolated Gate: very high input impedance and Voltage Controlling.

 

These look like a bidirectional insulated gate fet. They operate as switches, one on, the other off in sychronism with the switching input signal.
I could not find data.
A 4066 would probably do the same job and maybe replace Q1012 and Q1013 as well.

 

Hi
Yes, I too think that the circuit symbol represents something that could be replaced by a bilateral switch.
But how fast does it have to switch? Maybe the IGFETs outperform the 4066, so what is the frequency of the signal being synchronously detected?

 

I worked on something similar to this in the 80's that was a system that extracted a very low signal from a very noisy input.

The signal was modulated with the signal input level extracted using a phase sensitive
detector with the reference signal switching two mosfets.

In my case the mosfets were switching the signal to ground, in the case of your circuit the mosfets switch the signal directly.

This means that your device have to be capable of switching a bidirectional signal and probably must not have a drain source diode included, that reduces your choice of parts quite significantly as a great many potential candidates for replacement will include one of these diodes.

 

Perhaps a switching mosfet with a series diode might do the trick.