Ten Tec Argosy 525D, Near mint 9.8 condition, with mosfet finals coversion to IRF 510. Walk in Radio Shack $1.99 ea. or anywhere else for under a buck ea. The original finals were about $100 if you can find them! And even the substitute transistors were also on the brink of extinction. Rather than do it twice I decided it was better to convert to a main stream device. The mod only required 3 additional resistors, and replacement of a zener diode and 5k trim pot. The rig has been in daily service for over a year now with no decline in performance and proved to be as bullet proof as the Argosy itself. These radios have excellent receivers that are easy on the ears. Simple to use and maintain. Perhaps the ultimate portable, The rig outputs 20 watts RMS, probably a little less than the claimed 50 PEP with the original pair of MRF477. Radio is clean inside and out and needs nothing. The rig will come with matching power supply, stock mic, manual, extra schematic of amp reflecting changes and biasing instructions. I'm Perfectly satisfied with the output. However, now modified, it would be a simple matter to install readily available power mosfets with a higher rating. IFR520, 530, 540, etc will now all be excellent direct replacements. Or you could install the more costly RD15HHF1 power mosfet which is also becoming increasingly hard to obtain.. Unfortunately we are victims of the planned obsolence and counterfeit replacements of the RF transistor market. I personally feel this substitution only increases the value and long term reliability of the radio. Again this radio is working 100 % Put this beautiful Ten Tec in you shack for only $350!
Nov 10, 2012 - Replacing the obsolete and expensive MRF477 transistor with a .... uses a 1969 transistor and the later version uses a IRF520 MOSFET.