> Remember, the early receivers had something like 8000 ohms output instead > of anything much lower. Then a 600 ohm tap was added to the output > transformer in later models. That only applies to the USAAF's SCR-274-N gear. The USN ARA and ATA modulator, as well as the AN/ARC-5 and AN/ARR-2 always used nominal 600 Ohm AF output. 73, Mike / KK5F