Wow! It sounds like this was a 'cold' tune-up of a rig from out-of-band and not just a routine 'tweak' to get the sensitivety restored from months banging around in the trunk of a car ... I played similar tricks with a VHF High-band 1965 Motorola Motrac which I brought down from the 155 MHz area into the 2 Meter ham band (146 MHz) and xtaled it up for the local 146.88 MHz 'machine' ... this particular Motrac was the last of the MOTRACs to use a tubed transmitter with subsequent models employing sold-state exiter with just the driver and PA stages employing valves. The MOTRAC series started in 1959 as Motorola's "Transistor Research Line" and concluded sometime in the early 1970's ... the last UHF models actually employed ceramic-substrate based stripline RF amplifier driver technology driving a high-power conduction-cooled tetrode valve in order to achieve RF output power of 90 Watts at a 'cost' of just under 40 Amps DC at 13.6 VDC - most of that going into a switching power supply that ultimately delivered several different DC voltages into that somewhat 'exotic' transmitter arrangement ... Jim ----- Original Message ----- From: "Harold M Hallikainen" To: Sent: Friday, May 24, 2002 11:10 AM Subject: Re: [EE]: Sensitivity training for Engineers > I remember adjusting my vacuum tube mobile 450 MHz transceiver by going > up to the repeater site so I could hear it. I'd then drive away until the > signal started getting noisy. I'd then stop and go through the front end > tuning until the noise went away. This was repeated several times (on the > way down the mountain, I'd go through valleys, so the signal level would > drop pretty quickly). How's that for a high tech RF attenuator? > > Harold > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.