(a former group owner of AM, FM and TV stations, also a California publisher of newspapers, not to be confused with the present-day McClatchey Broadcasting LLC). The first Ampliphase transmitter was KFBK in Sacramento, CA (50,000 watts full-time). Later known installations were KOH in Reno, NV (5,000 watts days/1,000 watts nights). Other McClatchy AM stations like (KBEE, Modesto, and KMJ, Fresno, both of CA) employed conventional transmitters. Unlike most other commercial designs of AM broadcast transmitters Ampliphase units do not require expensive or large modulation transformers nor modulation reactors, thereby saving on the initial up-front cost. The down-side is the Ampliphase units require more maintenance. The Ampliphase concept trades a lower "Capital" cost for a higher "Expense" cost. Ampliphase achieved a modest improvement in transmitter overall efficiency before other amplification and modulation schemes could replace it. Obsolescence KFBK in the California still maintains an RCA BTA-50H (the "last gasp" of the Ampliphase concept) as an auxiliary transmitter. However, KFBK's main transmitter is a solid-state Harris unit, a prototype for which later renamed the DX-50. KOH has long since scrapped its home-built "outphasing" transmitter for conventional units. In the post-WWII era very few transmitters of this type were made, except for special purpose orders that kept the transmitter design nominally commercially viable into the 1970s. With the oil crises of the 1970s and 1980s Pulse Duration and Pulse Step Modulation schemes for AM transmitters took hold at power levels at or beyond 50 kw. Currently, the only manufacturer of AM transmitters that uses phase modulation to achieve AM is SRK Electronics. However, their design is implemented entirely in the digital domain, so avoiding the maintenance issues of the analogue Ampliphase transmitters. References External links Ross Revenge - Transmitter Room - Ampliphase Theory (see Ross Revenge). Ross Revenge Plans - Ampliphase BTA-50H. Radio electronics RCA brands Radio modulation modes