Hi, JB!
In principal it is! It depends on what system you want to rely on.
Here in the MULTIPLEX-Forum we only discuss the M-LINK-System by MULTIPLEX!
Unfortunately the original HF-Module (HFM3) for mc303/mc4000 Transmitters has no longer been in production for about 5 years. With some good luck you may find one on eBay - but you are not alone, so prices are relatively high for these rar items.
Two alternatives are possible: an external solution with the HFMx-M-LINK-module (still available at least on eBay) or the HFMG2-M-LINK that was produced für GRAUPNER transmitters like the mc19 or mc22. But you have to fit it in yourself which means you need a special adaptercable that is not available on the market.
so long
profimc