Présélecteur LOWE PR-150                                                                                                                     Retour accueil



Les modèles de pré-production (1992, testé par le WRTH - Cf. ci-dessous) avaient un système d'accord par diodes varicap. L'appareil produisait ses propres produits de mélange ... Les modèles commercialisés ont un système d'accord par condensateur variable qui a résolu le problème.




Manuel Lowe PR-150




The pre-production version submitted to Jonathon Marks, etc, at RN Media Network & WRTH 8/92 had it's problems - and a pre-amp on TOIP of -5 dbm. Additionally, it was varactor tuned. Subsequent redesigned production models fared better : +27.5 dbm TOIP pre-amp on (WRTH '94). They employed the varicap tuned tank circuits I described. Diode switching selects the lo-Z in/out of the inductors in the tank circuits while their hi-Z end is selected for the varicap by relays. The insertion loss of the passive preselector is stated at 5-10 db; the wideband pre-amp is rated at +10 db - clearly, it's main intent is to make up for the passive pre-selector's loss. It looks to be a typical no-nonsense wideband CATV-type BJT amp, the bias resistors suggesting a collector current of nearly 40 mA - the majority of the PR-150's current demand going there. Additionally, the only RF protection whatsoever is a 10 kOhm resistor from the Lo-Z (50 Ohm - SO-239) to ground to bleed static from a LW. There is a DC polarity protection diode in the power supply input as well.
I wanted the old tube-type RME preselector as a kid - it was as large as some radios then. I never found one... I wouldn't let the Lowe PR-150 slip away - and I am glad I didn't. Kind of a 'Holy Grail' type item to me. I use if now between my Pixel RF-PRO-1a and any of my receivers, including the R75, R30A, HF-150, R8, and NRD-525, the latter even having it's own tracking dual tank circuit preselector. I haven't tried it with my PL-660... yet ! Most of the time, the pre-amp is off. Definitely worth looking for !




    F-10255 - 2015