This may be the same problem as with using the Heil adapter with a Yamaha CM-500. The Yamaha has a stereo mic plug, with the element wired to both the tip & ring. The Heil adapter has a mono mic jack. Therefore, when you plug the mic into the adapter, you short out the mic element. I found a stereo to mono adapter on EBay for about $2. Plug it between the mic & the Heil adapter, & all is well.
I homebrewed a jumper for both. SB40 pin 7 to sleeve, pin 8 to tip. Bias off. SB45 pin 7 to sleeve, pin 8 to tip and ring (shorted at the jack). Bias on. If I recall I didn't need the +20db gain on either headset.