Re: SR 150
¿ªÔÆÌåÓýI believe it was the norm for 1960s transceivers. ?The Collins KWM-2/A and Drake TR3/4 series transceivers were designed primarily for mobile SSB operation and have similar CW limitations. ? ? I recently acquired my first TR-4Cw and KWM-2A transceivers and the Hallicrafters SR-400A is the better CW performer.? In CW mode, the KWM-2A uses an audio injection scheme into the balanced modulator.? To minimize close-spaced sidebands from the injection scheme, a 1700 Hz tone is used into the modulator then split to the receiver¡¯s AF stage for sidetone. ?A CW tone less than 1700 Hz results in multiple close-spaced carriers just as it does with the Collins 32S-1 transmitter.? I¡¯ve seen several stories that describe FCC citations issued to early 32S-1 CW ops. Later Collins transmitters solved the problem using traditional keying circuitry. ? Paul, W9AC ? ????? ? From: [email protected] <[email protected]> On Behalf Of robert cesarone via groups.io
Sent: Friday, March 29, 2024 8:22 PM To: [email protected] Subject: Re: [HallicraftersRadios] SR 150 ? I always wondered why there was no built-in side tone for CW in this rig. ? Possible reasons: Primarily intended for SSB use? Primarily intended as a mobile rig? Expected CW ops to be using the Halli paddle and keyer (with audio)? ? Does anyone know? ? I have an SR-150 in very nice cosmetic condition.? I haven't used it in a few years - but I have had it on the air.? I did a little CW with it - but that was rather difficult w/o a sidetone.? I'd like to get it on the air again one of these days. ? Nice rig: looks good; very quiet receiver. ? Bob C. WA9JIB ? = = = = = ? ? On Friday, March 29, 2024 at 04:17:55 PM PDT, waltcates <cateswa@...> wrote: ? ? There are those who say the SR-150 was Hallicrafters best ever transceiver. ? Thanks for the kind words on the repair document. They are all living documents, ever few months I take one and update it. ? ? Walt Cates, WD0GOF ? A majority of acceptance is not proof of correctness. ? From: [email protected] <[email protected]> on behalf of Don VE3IDS <ve3ids.don@...> ? Last summer I picked up a SR 150 and matching power supply/speaker. It was in the typical dirty scratched condition and didn't work. I wanted to say that Walt's repair manual was invaluable. I did the wash down with simple green rather than scrubbing bubbles because it was available. That worked very well followed by the garden hose and a few days in the summer sun. I sanded the case to bare metal and sprayed it with rustoleum hammered finish pewter. I recapped the supply and the electrolytic capacitors in the rig per Walt's doc. I followed the alignment tips and found that I needed to shift the USB carrier oscillator a bit to bring up the CW power levels. Thanks Walt, the tips in your manual are gold. I'm not sure if you were a technical writer or not, but I haven't seen better service docs. I still need to spend time on the vfo tracking across the dial but that can come later. I also added a side tone oscillator as I am primarily a CW op and prefer using a bug. I made up a little board with a couple relays, one to switch the grid block voltage and one to switch the audio output from my side tone oscillator. I now have 12 volts on the key instead of grid block voltage. This is all easily removable with no non reversible changes and I leave a printed note with the mod details inside the cabinet in a cool location behind the bottom cover. I am impressed with how stable the vfo is and the nice comfortable sound to the receiver in this model. The first contact was a nice chat with an op in France. Lots of fun!? ? 73 Don ve3ids? |
Paul Christensen