Collins 75S verses a Drake R4

Discussion in '"Boat Anchor" & Classic Equipment' started by KB4MNG, Nov 4, 2016.

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  1. WA1GXC

    WA1GXC Ham Member QRZ Page


    Always wanted a R-390A. Will never get one. I'm pretty good at learning mechanical/electronic circuit architecture with enough time and hands-on--
    but I believe many will tell you the R-390 and R-390A are mechanical nightmares. If you were not a technician in the military or NSA and worked on one
    before, it's pretty daunting.

    Always wanted a Collins (civilian) radio since I was a kid. Who didn't? . Got a 75S-3C 35 years ago, was primary receiver for awhile. (1966 build). Having later
    used all kinds of professional gear, vacuum-tube, hybrid, and highly-sophisticated solid-state, the Collins leaves me cold. Mine is aligned properly
    and I characterize it as a 'pretty good, not superb' receiver. Note well Glen's earlier post about Collins Radio cutting costs through design changes for the 75S-3B/C.
    Mechanically, like all Collins, it's a masterpiece and I'm pleased to be an adult who could afford (3rd-hand) my dream acquisition. But as Mr. Spock once sagely
    pronounced, "Having is often not as pleasing as wanting."

    I have R-4, R-4A, R-4C of both circuit designs. I never used a R-4B but from reading may reasonably assume it's similar in most ways to R-4A--same IF-filtering architecture.
    The R-4A (I have 2) are my favorite receivers, more so than the -4Cs. They are essentially "all-tube" (almost) radios and sound like it. If the bandpass filter assembly is aligned properly,
    it's as sharp as you'll ever need for difficult CW communications.

    The R-4C's are great receivers, but fetch more on the market. Also, being moderately transistorized, they are succumbing to random transistor failures starting at 40 years of service
    (my observation) and replacement transistors which are appropriate are themselves now obsolete. I've had unsatisfactory performance from generic "NTE-type" replacement transistors.
    The circuit boards are high-quality and good QC, but tightly-packed and require a lot of patience and technique to remove and replace components.

    R-4A at hamfest around here -- $125
    R-4C at hamfest around here--$200-300

    Buy 2 and get 2 better receivers for the price of 1.

    73
     
    Last edited: Oct 7, 2020
  2. G3YRO

    G3YRO Ham Member QRZ Page

    Yes, the strange thing about the Drake R4 Receivers is that you would imagine that the LAST version was the best . . . but in fact each of the different versions have their Pros and Cons.

    I have used R4Bs and R4Cs . . . but owned an R4A for about 35 years. (sold it to make room for a new rig about 4 years ago)

    If it was possible, I would take some of the different features from EACH version, and make a composite ! (although not possible, due to the different frequency conversions)

    Roger G3YRO
     
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  3. KC3NDU

    KC3NDU XML Subscriber QRZ Page

    G3yro. In your opinion, which of the R4's would be best for cw?
     
  4. KK6IYM

    KK6IYM Ham Member QRZ Page

    I have a number of radios of all makes and types and repeats of some. Because of the age and the number of components, many of which change in nature over time, some radios are just better than others--even though they may be the exact same model and have had full restorations--short of replacing every component with a new version--which is impossible anyway. Collins radios are great radios--the 75S3 especially. The Drake R4B is another great radio. I have a Hammarlund HQ 180 that is fantastic. But I don't expect every HQ 180 to be that great, or every 75S3, or R4B, because I have others of these that do not work as well, or need a return to the test bench if they are out of use for a period of time. I tend to suspect that when people say they don't like a certain known quality radio, it is because they have had a bad example that they use for comparison to a good example of another brand.

    Yaesu FT101ZD, Kenwood TS830S, Collins 75S3, 32S1, Heathkit SB310, Collins KWM-2, Drake R4c, T4XC, Hammarlund HQ 140XA

    Norm

    IMG_5212.jpg
     
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  5. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    Second that. I had a Drake C line and have been kicking myself for some 25 years since for selling it.

    I have been very tempted to pull the trigger every time I've seen a pristine complete C line, but day-um, people are (rightly) proud of 'em. I just couldn't talk myself into spending that much money when I have modern radios that are better by objective measures and, if I didn't, I could buy one with money left over.

    Every time I see a really nice C line for sell I get a little closer to giving in to the temptation to buy it.
     
  6. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    [deleted - have my opinions but don't we all?]
     
  7. W9BRD

    W9BRD Ham Member QRZ Page

    I've owned the R-4A, -B, and -C; for me, the roulette wheel stops with the -A (13-tube version). I also prefer the 13-tube -A over 11-tube -As and the -B and -C, because I think its 6GX6 product detector sounds smoother that the solid-state product detectors used in later versions. (I don't use the set's pitiful inboard AF power amplifier, BTW; the wiper of my R-4A's AF GAIN control goes to an added RCA jack on the back panel so I can do the set justice by listening to it through my AF filter/amplifier box ( http://dpnwritings.nfshost.com/ej/pictures/pictures0.htm ).

    Oh, I bought my R-4A on Ebay as nonworking--for $125. Although its cause was not helped by a brainiac having replaced its 6EH5 with a 6AS5, it was outright inoperative because its "crystal/VFO" switch was set to "crystal."

    In my opinion, the -Cs IF-filtering improvements were offset by Drake's destructive fiddling with the set's AGC distribution across stages. The R-4C has too many AGCed stages ahead of of its crystal filters, with the result that there's noticeable strong-signal-onset popping when narrow CW filters are switched in. (This occurs as a result of time delay in the filters. Signals take longer to pass through narrower filters than wider ones. The result is that the large AGC-voltage change necessary to control the leading edge of strong-signal onsets arrives at the ahead-of-filtering AGCed stages a fraction of a second too late to help.) No amount of Sherwood Engineering magic can remedy that, IMO, and I'm done with grossly redesigning gear to fix engineering mistakes.

    BTW, as I describe in my page at http://dpnwritings.nfshost.com/ej/drake/, there is nothing magic about 6HS6s regardless of how lore may have informed you about the 6HS6 being "hotter" at low plate voltages than the 6AH6. The 6HS6 was a cheaper, heater-warmup-time-controlled 6AH6; that's all. In my R-4A, the RF mixer is now a 6DK6 (with 150 mA more heater draw added with shunt R to bring the total heater draw up to 0.45 A like the 6HS6 it replaces) after swapping the grid 3 and cathode connections to the socket. The set works fine.
     
    Last edited: Oct 12, 2020
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  8. WA1GXC

    WA1GXC Ham Member QRZ Page



    I was cheered to see your essay some time ago about 6AH6 operation versus 6HS6. I went to 6AH6 long time prior on the basis of me being cheap.
    I could not discern any operational difference in the receiver performance. 6AH6 still dirt-cheap at Surplus Sales of Nebraska. I have 40 N.O.S.
    in inventory in case Offut AFB in Omaha gets irradiated.
    The audiophile wizard-fools have bid-up 6HS6s to bizarre heights.

    73
     

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