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write your own review of the Collins 75A-4.
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K5FZ
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Rating: 5/5
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Dec 1, 2004 12:41
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GREAT RECEIVER
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Time owned: more than 12 months
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This was THE best receiver on the market at the time it was built...IF there were any design flaws they certainly weren't obvious at the time.
I was able to scrape my pennies together and buy one of these great receivers used in 1971 and it was THE best receiver I had ever used at the time.
I am sure when used side by side with modern rigs is comes up short, but we have only had 50 years of technology pass under the bridge since these fine old rigs were built.
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KQ6IG
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Rating: 1/5
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Nov 30, 2004 21:48
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Rather Poor
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Time owned: more than 12 months
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Although an attractive receiver, the Collins 75A-4 is a rather poor performer. I purchased mine with high expectations, but was disappointed on most counts.
If you get past the design flaws like the mixer overload problem, the poor sensitivity, and bad AGC action, you still have to contend with the mechanical filter issue. The rig only came with one 3kc filter. This works well for SSB, but is too narrow for good AM, and not suited to competitive CW. Original filters are expensive, and hard to find.
On the bright side, the rig is historically significant, attractive, and fun to use under the right conditions.
I ended up selling mine. I woulden't pay more than 150.00 for another.
Omar
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W9CW
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Rating: 5/5
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Dec 31, 2003 02:02
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Excellent Receiver for Its Time
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Time owned: more than 12 months
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One has to view the 75A-4 in the timeframe of its design and intended use. For 1955, the 75A-4 was the "Cadillac" receiver. And, contrary to some of the previous reviews, the final version of the A-series Collins receivers was designed and marketed primarily for use on SSB, CW a strong second, and AM a distant third. For proper use on AM, the 6.0kHz mechanical filter must be in place. Otherwise, the fidelity through the standard 3.1kHz filter is greatly diminished. If everyone using a modern day "Ricebox" would only listen to a properly maintained and aligned 75A-4 today, they would be amazed at the quality of the recovered SSB or CW audio. Connected to a good quality, and large 4 ohm speaker, the audio is abundant and extremely articulate. One can fill an entire room with audio from the 6AQ5-based audio strip in the 75A-4. Although Collins rated the output at only 0.75 Watts RMS, 100 Hz to 5kHz +/- 3dB at less than 10% THD, their ratings must be "extremely" conservative as compared to today's audio output ratings in transceivers. The A-4's audio output will literally blow most new rigs out of the water.
Collins tube audio is hard to describe until you've listened to it for a while. The articulation is so good you may never wish to listen to a solid-state audio amp again. And, this comes from one who uses primarily Drake, ICOM, Kenwood, and Ten-Tec gear!
Yes, the receiver does have some deficiencies in gain distribution and noisy 6BA7 mixers. But, at the time of the design, dynamic range was not the primary design focus. Sensitivity, selectivity, and stability were however. For its time, the 75A-4 was the ultimate receiver. And, it has stood the test of time quite well. How many current day "Riceboxes" will still be in use after 48 years?
73,
Don W9CW
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WA3VJB
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Rating: 1/5
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Aug 22, 2003 16:38
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Awful on AM
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Time owned: 0 to 3 months
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My first-hand experience with the 75A4 is limited to "trying" to use the receivers owned by others during brief visits to the AM gathering points on 75 and 40 meters.
I was very disappointed in the quality of receive audio.
Puzzled, since this receiver has been held in high regard, with market prices reflecting this, I did some research and some asking-around among owners and users.
Turns out the 75A4, as designed, includes an unacceptable amount distortion in the audio stages and a lack of adequate bandwidth on AM receive.
There are many modifications to re-work the audio stages to minimize this distortion, and there are aftermarket filters to give a decent slice of bandwidth for reception with this improved audio.
Stock? Most people using them for AM on the shortwave ham bands will tell you they don't sound very good. Many are left "on the shelf" as conversation pieces, tubes unlit, radios unused.
Moreover, the receiver is an orphan, with no matching Collins AM transmitter. It is smaller than the 32V series transmitters, and was not meant to pair with senior Collins models like the KW-1, 30K, or any of the Collins AM broadcast or military transmitters enjoying widespread use on the ham bands.
It does fit the the KWS-1, which provides incomplete AM at similar levels of distortion.
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K6ZL
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Rating: 3/5
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Aug 21, 2003 02:40
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A big name, Ok receiver
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Time owned: 6 to 12 months
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I've owned 3 of these. One was Like new, one in poor shape, and one in the middle. Collectors have driven then "out the roof", price wise. The were designed primarily for AM & CW, and do well there. But on SSB
all of mine displayed slow rolling drift. If you gotta have one, get it. They look great on the shelf.
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KD2E
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Rating: 3/5
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Nov 3, 2002 17:27
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Fairly nice
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Time owned: more than 12 months
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I love to use my A4. Tuning around with it is a joy! It has great frequency readout, and stability. But, that is all it does very well.
The little Drake 2B is actually a better receiver in many respects...just doesn't have the same 'feel'
I used to have the matching KWS1, but didn't use it much and sold it off.
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N8FVJ
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Rating: 4/5
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Nov 3, 2002 12:54
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Great, audio needs 'a little'
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Time owned: 3 to 6 months
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Great receiver, however the audio is not great. A few modifications did clear it up just fine. What makes the radio desirable is the stability, real passband tuning, selectivity and the analog dial that allows anyone to find a frequency! And, 'its a Collins'.
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WB6MYL
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Rating: 5/5
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Aug 14, 2002 19:38
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argueably, one of the best ever
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Time owned: more than 12 months
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I, as with the previous reviewer, have a large collection of receivers/rigs (probably 50 at last count). I love my R-9000, TR-7, FT-1000D and the 51J-4; these are great rigs and special in their own right; however, when it comes to fidelity it is hard to beat an A4 for listening pleasure; that wide open audio that Art and his boys put in that St James box is hard to describe except for "very analog" and "tooooobey"; this is deemed even more impressive considering you are talking about fifty year old technology. You can find these things sitting in garages and attics with years of neglect, plug them in, and many hear very well (yes you typically have to recap and/or retube but it is worth it). Argueably one of the top two or three amateur band receivers ever made; Best analogy: listen to the top of the line stereo receiver from a hi-fi jobber and compare it with a set of 60s vintage McIntosh tube monoblocks; great pass-band (although I beleive the Drake passband is better) and best sounding rig in my shack with the exception of my 390A/TMC 591 SSB adapter; I wish I could get these black beauties in my 401K.
Thanx for reading. Phillip W. Harris, PhD.P.C.
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N4UE
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Rating: 5/5
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Aug 12, 2002 17:44
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Still incredable performance
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Time owned: more than 12 months
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Hi, let me preface this by stating I collect receivers. I have a lot. My pride and joy, is a perfect example of the state of the art in 1955. I own serial # 029. I purchased this radio sight unseen upon the recommendation of K8DR, from W4XO. I was told that my radio was "nice, but needed the usual recapping, etc" , a 'working radio'. The radio arrived in the most elaborate packing I have ever experienced! Even the Xtal calibrator was removed and wrapped in styrofoam, as were the filters. The condition of the paint was near perfect. This radio had the 4:1 knob and gears installed, which I feel is mandatory. I immediatly thought that this radio needed a companion speaker. After having sticker shock at the 270 series Collins speakers, I ordered one (reproduction) from Mort Jones. I defy anyone to tell it is not origional. What is really amazing is that the paint is a perfect (and I speak as a car builder) and I mean perfect, match to old # 029. Several ham buddies simply cannot believe how good it looks. They swear it is a matched pair. Mort, I don't know how you do it.....unbelievable......
Back to the radio......It played perfect, out of the box. part of 10 M was dead, but that was just a matter of tweaking the osc. coils.
I left the radio alone for about a year, because it worked so well, I just couldn't imagine it being any "better". And this is from a ham of 45 years, (and a retired EE), who can't leave ANYTHING alone! During this time I acquired many new HF radios including an Icom 756Pro, a 706G (both bought by me, in Tokyo and carried on the plane back). The A4 could hold it's own. One day I decided to re-cap the thing. I gathered all the information on the WWW and gathered the necessary parts. I bought the 75A-4 video from the CCA and followed Chuck Rippel's advise about the 'deadly caps'. Sure enough, all (!) the bypass caps were NFG as were several of the micas. I did the mod to remove the B+ from the: 500Hz. 1.5KHz. 2.1KHz and 3.1 KHz filters I had acquired. I did a complete alignment. Some specs were right on, othere were WAYYYYYY out. The result? Probably the best radio I have in my museum/collection. I have a mint '67 EAC R390A with a CV-571A SSB converter (yet to be 'refreshed') so I can't rule this combo out..... However, the only other tube radio I have that can play with the A4, is my Collins 51J3. Recently, I purchased a PD-1 (Product Detector) for the J3, and I have not used it yet.
To 'spruce up' the A4, I polished the tube shields, painting the inside of them black. The chassis is absolutly 100% mint and sparkles like the day it was made. I put the dial drum in my lathe, turned off the old decal and put on a reproduction.
Digital pictures of this radio cannot possibly do it justice! It has earned it's own dedicated table in my museum.
When my new shop/shack/museum is completed this year, I hope to be able to replicate these efforts for any Collins fan at my cost. These are unbelieavable radios and you should acquire one at any cost! They are worth every penny. Trust me!
ron
N4UE
Moving to Lake City Florida
EM80
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