[Milsurplus] ARR-15 receiver

[Jim Whartenby]

Enclosed is the IF mod that I did also included is the 73 magazine mod which I did not do.  The audio filter has a relay built into the housing.  IIRC, 28 volts energizes the relay to make the filter do low pass audio duty. I have several ARR-15s, a few are pristine but most have some degree of ham mods.  I might have the antenna connector stripped from an organ donor.  I can check the parts box if you need another project!  <grin> Still a nice radio which appears to be the foundation for all Collins receivers designed post WW2.Jim
Logic is a systematic method of coming to the wrong conclusion with confidence.  Murphy

On Monday, November 2, 2026 at 04:30:18 PM CST, Hubert Miller <kargo_cult at msn.com> wrote:

 I had in the mid 1970s A.D. an ARR-15 i bought from a vet. It was MARS - acquired and still in some kind of large cardboard barrel. I bought from Fair a 24 DC supply and ran it that way. Yes, there is a definite "noise floor" running on dyno, altho i did hear some interesting SWL type things, such as a game show over BBC, just above 5Hz, Kuching Malaysia. My barber, who is from Malaysia, was surprised at this story.I have 2 of ARR-15 now, one with dyno. The odd thing abt the one with dyno is, the pushee antenna connector has been changed to BNC. I don't get that. If it's a ham mod, why run it on 24 DC still ? When i did run it on 24 DC, i had an excuse: i didn't know better.There used to be on the net some article abt tightening up the IFs by decreasing the low pF coupling caps. Article is gone now. I wonder if anyone here has done that. I think the tuning rate is too fast for CW and certainly SSB, so i'm thinking the +- 50 kHz 'calibrate' feature can use improved selectivity. In other words, to be clear, can one improve the selectivity and use the +- IF feature for fine tuning ? In those olden days, for SWL BC, AM mode only, the main tuning knob was good enough. Another thing i want to figure out is that audio filter. The manual doesn't really explain its working or innards. Lastly, let me mention that i never noticed any audio distortion from the always - on noise limiter. That circuit actually does have its own unique name, after the designer, but i cannot remember it at this moment. -Hue Miller

Sent from my Galaxy

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