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Reviews Categories | Receivers: Vintage amateur | Collins 75A-4 Help


Reviews Summary for Collins 75A-4
Collins 75A-4 Reviews: 23 Average rating: 4.2/5 MSRP: $695
Description: 10-160 meter AM/SSB/CW Receiver
Product is not in production.
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G8AQN Rating: 5/5 Jul 20, 2005 08:19 Send this review to a friend
Great quality & performance  Time owned: 3 to 6 months
I have read a number of reviews regarding the 75A-4 some good to excellent & some bad, however I would like to add my bit regarding this great receiver.
I bought mine on the German Ebay site, with caution I might add, due to the fact that it had been modified somewhat,the seller stated that he had modified it with SSB as his main interest, he had replaced the mixer stages with 7360 balanced mixer/modulator valves which were popular back in the 60/70's, as per W2QWS's suggestions in QST dated July 1964, plus he had changed the AGC for fast attack & slow decay times, he also relaced L27 IF tuned cicuit with a 3.1KHz. Collins mechanical filter for use as a noise roofing filter, the same type as is used in the receiver selectivity stages.
When it arrived the 75A-4 was in very good clean condition, with no signs of black staining under the chassis as is evident with a lot of use, I was very surprised at the quality of the workmanship done during the modifcations & replacement of parts obviously done by a professional wireman, after the usual visual & safty checks I switched the radio on, & "WOW" what a performer, there were no cross mod. & blocking problems as some of the reviews suggest even on 80Mtrs in the evening when the band is crowded, & good sensitivity with low noise level, the stability of the oscillator is superb, I measured 200c/s drift from switch on in the first quarter of an hour, with minimal drift of 150c/s during the day.
I promptly ordered a 6 & 9KHz. filter from Electric Radio for AM use, these arrived a few days latter & were fitted, the 9Khz. filter replaced the 3.1 KHz filter that was fitted in place of L27, the 6Khz. filter was installed in it's usual holder.
I must admit that the audio on the 75A-4 did sound a bit strange, it had very "edgy" sort of sound, I tried a number of metal cased speakers of all sizes with no difference in sound, I was beginning to get a bit frusterated so I decided to tackle the audio stages, this turned out to be a red herring & a waste of time, in desperation I tried a 1930's extension speaker which was fitted in a wooden cabinet, & beleive it or not, the 75A now sounds great, so try it!!
As regards to SSB performance, it is not fair to compare it to the modern receivers, after all the 75A-4 was produced in the early days of SSB , so come on, I don't know of any other receiver as good as this from this era.
I know that the purist & collector ( I am one of them) believe in the original design, but my 75A-4 is superb & I have no intentions at this stage to reverse the modifications, I use mine regulaly on the 40 & 80Mtrs AM nets.it's a great receiver as it is. If one comes along at the right price in original condition then I may buy it if only to compare it with my modified one.
I would not part with my 75A-4 for anything.
73's
Tony G8AQN

 
K1YPB Rating: 5/5 Dec 2, 2004 13:25 Send this review to a friend
Excellent Receiver - Keeping in mind what it is and its vintage  Time owned: more than 12 months
I am a proud owner of a 74A4 manufactured in March 1955. It is in excellent shape with all the filters, and works pretty good.

In reading all the reports I can agree with a lot of the opinions offered. I think that considering what this receiver is, and when it was designed and the technology at the time, this receiver is pretty much (or was) "state of the art" Ever since I was a kid (got my ticket in 1962) I desired to own one of these extraordinary receivers. I was finally able to obtain an excellent condition unit a few years back.

It really is not fair to compare this to say... a TS2000 (which I also have). The new digital DSP rigs run circles around these old boat anchors. But... out of respect of what these receivers represent, they still do a very respectable job receiving signals through the QRM. Good filters in combination of a properly operating PBT, along with knowing how to set the other controls in conjunction to what you are receiving renders some still pretty respectable performance. And it is still kind of nice (nostalgic) to see the tubes glow, and enjoy the sights, sounds and smells of a tube powered radio. In our modern adjustment free radio environment of today we are pretty used to pushing a function button and having the DSP or whatever so to speak automatically take care of the function. These older rigs took a little "balancing of the controls" to make the difference between exceptional performance and marginal performance. Quite often that performance was resultant of the operator's skills in that regard, rather than the rig not working properly (ie complaining about crowded band performance while the RF gain control is set at full gain, or maybe the wrong agc time constant selected.

In fairness, I give the 75A4 a "5" from a 1950's 60's evaluation vantage point. From todays vantage point... maybe a "4". I think it all needs to be kept in perspective.

Dan
K1YPB
 
K7NG Rating: 4/5 Dec 1, 2004 17:01 Send this review to a friend
Good, not great  Time owned: more than 12 months
I owned a (used) 75A-4 for about 20 years. During that period I had occasion to use it in several different setups. I must say that the audio quality is second to none. Compared to receivers of similar vintage I can't think of any (except for maybe the R-390A)that perform any better in terms of selectivity or sensitivity. But if you were to compare the 'A-4 to a modern receiver, I think you'd find that the newer rig actually outperforms the old 75A-4 in almost every specification. Though the 455-kHz mechanical filters were (and are) the best in existence, the filter blowby, reciprocal mixing due to oscillator noise, high noise figure of the front end and mixers, etc. make the 75A4 second rate today. But if you like the look and feel of the A-4, and enjoy the sounds that come out of it, and aren't trying to win a big-time contest, you can't beat it.
 
W2XS Rating: 3/5 Dec 1, 2004 12:44 Send this review to a friend
The Drakes are better  Time owned: more than 12 months
I once did a side-by-side comparison of the 75A4 and the Drake 2B. I was interested in CW QSK performance - receiver overloading, AVC action, and clean sound with good QSK with an external T/R switch. (QSK is the ability to hear in-between the dots and dashes even at high speeds). To make a long story short, I sold the 75A4 and kept the Drake 2B.

These days, I prefer the general-coverage boat anchors for SWL and AM BCB listening, and any Drake R4x receiver for boat anchor ham operating.

Then again, the 75A4 is very impressive looking, has a great dial, and was the first receiver with the incredible feature of passband tuning.
 
K5FZ Rating: 5/5 Dec 1, 2004 12:41 Send this review to a friend
GREAT RECEIVER  Time owned: more than 12 months
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.
 
KQ6IG Rating: 1/5 Nov 30, 2004 21:48 Send this review to a friend
Rather Poor  Time owned: more than 12 months
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
 
W9CW Rating: 5/5 Dec 31, 2003 02:02 Send this review to a friend
Excellent Receiver for Its Time  Time owned: more than 12 months
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
 
WA3VJB Rating: 1/5 Aug 22, 2003 16:38 Send this review to a friend
Awful on AM  Time owned: 0 to 3 months
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.

 
K6ZL Rating: 3/5 Aug 21, 2003 02:40 Send this review to a friend
A big name, Ok receiver  Time owned: 6 to 12 months
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.
 
KD2E Rating: 3/5 Nov 3, 2002 17:27 Send this review to a friend
Fairly nice  Time owned: more than 12 months
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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