HFU HF Underground
Technical Topics => Equipment => Topic started by: Radioroom on December 14, 2021, 1502 UTC
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I have been using the R-390a for over 40 years in my shack. My shack is fairly extensive but I always seem to gravitate to using the R-390a for all types of listening. I have 3 of them including one at my cottage in the ultra-quiet listening environment along the shores of Lake Huron. I'm curious to know what other users think of them.
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Never had one but always wanted to try one out.
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I have been using the R-390a for over 40 years in my shack. My shack is fairly extensive but I always seem to gravitate to using the R-390a for all types of listening. I have 3 of them including one at my cottage in the ultra-quiet listening environment along the shores of Lake Huron. I'm curious to know what other users think of them.
The R390a / URR is an undeniably good radio. I have two, a low serial Collins and a late Stewart Warner. The receiver noise is very good, very low noise. The LO phase noise is very good. And the pre-selecting tracking front end is outstanding.
But, I find I don't often use mine, other than just to use them because I specifically want to. While good they are not better than several other radios I own, indeed not as good as several, and they do not bring to the table some of the features of later radios. When I use it, I tend to set the R390a on a frequency or station and leave it there while I use other radios to actively do things. I treat them very much like I treat other old school radios I really like, my Collins 51J-4, Hallicrafters SX-28 or the Hammarlund SP-600, for example. I use them more for the nostalgia than any other reason.
For basic receiver capability I place several, many, of my other receivers ahead of the R390a. I feel that my Flex-5000a, Yaesu Fdx-5000, Icom R8600, and Winradio G33DDC all beat the R390a in every imaginable way. Several other radios I have here may fall behind the R390a in some way, but make up for it with the other features they bring to the game. For example my RFSpace NetSDR may not equal the R390a in receiver noise floor or front end blocking, but it brings so much else to the fight that I will still take the NetSDR every day over the R390a.
Time marches on, and while old school top shelf radios like the R390a are fun to use, and take me back to the first time I spun the dial on such radios, there are better radios to be had. Shoot, I still occasionally fire up the very first receiver I ever bought, a Hallicrafters SX-99 I have owned over 50 years. And that really is not a good receiver, but the memories I get out of turning the knob on that (and the LM-18 frequency meter I use with it) make it an old friend.
So the radio you use, as long as it is adequate for the task, is much less important that how you enjoy using it. But, if the radio you enjoy is something as good as the R390a, then so much the better.
T!
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Thanks for your thoughtful reply! I personally do not compare mine to all my digital radios including my newer Icom 7610 because IMO they are two completely different animals. I rarely use my R-390a for the ham bands as I agree my current rigs are so much easier and enjoyable to use for that. It is certainly not my choice for SSB reception either although I can get it sounding decent in that mode. I like it mainly and pretty much solely for SWL AM, numbers stations AND especially Broadcast Band DXing. In my opinion, broadcast band listening at night is where the R-390a shines. There is simply nothing that comes close it (all my rigs digital and otherwise including my RACAL 6790) can't touch it. A properly aligned R-390a is simply magical in what is discerns on the broadcast band. Spend the hour or so it takes to properly align one of these and you will be rewarded. You have to use a 600 ohm speaker OR a small amplified speaker hooked into the back or the headphone jack but doing that will provide deep, outstanding, room filling audio. Enjoy the listening fellas from an extra in W8 land!
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Without having done any experimentation whatsoever, I wonder if the warm room filling sound the old radios have are a result of the artifacts of a tube audio amplifier or the big beefy enclosure that the speaker sits in, or both. :)
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Actually a good larger 600 ohm speaker like an old Hammarlund or Hallicrafters will give you an excellent result per radio spec without having to go to the amplified speaker route because of only having an 8 ohm speaker on hand. Most SWL hobbiests won't have a 600 ohm speaker sitting around. True, warm tube audio from a radio is certainly a plus BUT a small amplifier with controls for treble and bass sure doesn't hurt either if you need to go that way!
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I have a R390 Collins made that has original paint and meters. I have done very little repair work on it. I also have a R390A that I have restored it adding original meters to it. If you want to experience newer performance on both add a SDR interface to the 455Khz IF or add a tap on input BNC connectors before the filters for a wider spectrum display. Run your SDR software. The only thing is to keep in mind you will have some frequency drift over time which I minimized by adding a stable filament voltage regulator to the PTO VFO. I prefer the R390 performance over the 390A cost reduction version (except the mechanical filters) and by using the SDR you get the advantage of the brick wall filters anyway. One big advantage is you can use the 390 /A in a high RF field as long as it is not in your passband because of the excellent front end selectivity.
For very good stability I may add a VFO stabilizing circuit to the PTO or switchable in out DDS VFO. This is just a possible future update but not necessary for most listening conditions.
By the way you can add a simple mod that will allow the R390 to go below the broadcast band.
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Hello MRI, I would be very interested in the mod to make the R-390a go below the broadcast band. I have done only the AGC diode mod which works very well. Can you enlighten me on what that LF mod might be?
Thanks!
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Hello MRI, I would be very interested in the mod to make the R-390a go below the broadcast band. I have done only the AGC diode mod which works very well. Can you enlighten me on what that LF mod might be?
Thanks!
Hello Radioroom. All that is needed is a in a .01 disc capacitor connected to test point E209 going to your antenna with one end to ground. For best results use or make a bifilar antenna isolation transformer for ground loop hum and common mode rejection. The 390A will go down to 20Kc. Disconnect this antenna input when using higher bands.
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Hey All,
I have SEEN 390's a number of times at ham fleas, but have never operated one. SO COOL though ! Once upon a time , it was THE Military receiver.
The best I've ever done was the Icom R-70 and R-71a (long gone, along with the big antenna). I found out that the '71a was used by USMC intel and other "pro" grade users ( diplomatic, etc) .
NICE stuff , but NOT hollow state.
Despite "listed" spec, the '70 would still "respond" to very long Dx static crashes down to around 10 Kc before diving off the cliff. 24 Kc NLK/ WA was no problem here in Boston.The '71 would go totally deaf maybe 5 or 10 Kc higher than the 70. Above 40 or 100 Kc , both were GREAT rigs.
Anyone who has a operating 390 has quite a piece of history in their shack !
K
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Don't have one, have yet to try one, read extensively about them, so I want one! Yeah... You should have included that in your survey, "I WANT ONE!". Talk about a rig that 'nailed-it' for things to come, before the age of digital read-out, that was very forward thinking for it's time, and its standards are still a model to base a rig's performance, today. That sells me.
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Collins R-390a
Technical Manual (pdf)
http://t.co/8bbfuRGtdd (http://t.co/8bbfuRGtdd)
André
CoolAMRadio/OHR
the Netherlands
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I have one that has bad caps, resistors, and whatnot replaced, aligned to perfection by a perfectionist who is fairly expert in these rigs by now. It's the most sensitive rig here, hearing things others do not on the same antenna such as sucking a T600 (fsk) sig out of the noise clearly, when the other rigs don't hear it at all. It sits unused most of the time due to heat creation/power consumption, as well as other rigs being simply more effective (meaning ease of use for the most part) at whatever I want to copy at the time. As said they're stellar at ambc and hfbc - something I note is how good the stock detector for am is, I compared it to my RSP2 using synch and a few HAM rigs with ecssb, time and again the 390A pulls out more and better copy. At the time of its creation/service life there was little else that could do what it did, combining strong signal defense at the same time as having incredible ears, excellent for its time stability, and freq accuracy/repeatability. I use it with a variac and feed an old Hammarlund speaker with a 600 ohm xformer. One thing not often mentioned is the few birdies, very clean as far as spurs go. Not as spur free as the Winrad 313i wich you think should be filled with spurs since it's inside a freaking pc, but I digress. Might still work after Putin or whoever lobs some emps our way.
sherweng even tested one;
http://www.sherweng.com/table.html
https://www.dropbox.com/s/ddrji5c9a1q25ag/Sensitivity%20Figures%20on%20Some%20Receivers.pdf?dl=0
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here's a couple video's you guys may find interesting
SOLID STATE CONVERSION
https://www.youtube.com/watch?v=xhWzX874wYo
https://www.youtube.com/watch?v=RRZ04OKV9pQ
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Interesting conversion. Nice to see some new life into a classic receiver. Thank you for that solid state conversion post and links.
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As far as stability on the R-390A I re worked the cosmos PTO VFO for mechanical stability and now after full warmup the drift is now 4Hz with the heaters off. Just amazing for a receiver that is 59-71 years old.
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We had one decades ago at the club station at my university. The enclosure was pretty beat up with a lot of scratched paint. Maybe it was banged around a bit in the Korean or Vietnam Wars. It worked OK but I always felt like it needed an alignment since it it felt a bit "unresponsive" and maybe the AGC wasn't quite right. In any case, I listened to many hours of Radio Dublin and Radio Fax (the station, not the mode) on that bad boy.