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Author Topic: regen vs direct conversion receiver  (Read 8656 times)
NOTBOB
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« on: August 06, 2010, 08:59:47 PM »

I'm still studying for my exam and learning morse code, but would like to start listening.  Ten Tec and Qrpkits make affordable (< $50) receiver kits that are within my building abilities.  The question is, which is best for listening to cw and phone?  A regen or a dc receiver?  I've read the pros and cons on both, but am still not sure which would suit my needs.  Basically, I just want something to catch the arrl code practice broadcasts and maybe see how far away I could pull in a signal with my first attempt at an antenna.  I just might get both to experience the difference for myself. 

nb   
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N4CR
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« Reply #1 on: August 06, 2010, 10:16:41 PM »

Some of the top receivers on the planet are direct conversion. None of the top receivers are regenerative.

That should pretty much sum up your choices.
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73 de N4CR, Phil

Never believe an atom. They make up everything.
G3RZP
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« Reply #2 on: August 06, 2010, 11:22:08 PM »

Direct conversion is very good if done correctly. If not, it can have problems, usually a tendency to detect AM signals which are off the frequency to which it is tuned. Regens are poor at signal handling, can have problems with AM overload, and have inherently poorer selectivity. Of the two, I'd go for direct conversion - regens are a fun thing to play with, but not high on  performance by today's standards.

A 'proper' direct conversion rx uses two channels - I and Q - which have the signals at 90 degrees in phase. This allows better signal processing, and with some complications, can even receive analogue FM. Simple ones just have one channel, and will do CW and SSB reasonably well.
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N2EY
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« Reply #3 on: August 07, 2010, 05:12:23 AM »

If you're talking about modern, currently-available kits for listening to the amateur bands, your best bet is a direct conversion design.

The big advantage of regenerative receivers is absolute best performance from the absolute fewest parts.  When parts and tubes were expensive and hard to come by, that was an important consideration, but nowadays the more-complex direct conversion designs cost only a tiny bit more.

73 de Jim, N2EY
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W8JI
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« Reply #4 on: August 07, 2010, 05:30:28 AM »


I would say most answers so far are misleading........

There are various levels of direct conversion.

Some are not much better than a regenerative receiver, only the much more expensive and complicated quadrature phase types of direct conversion are exceptionally good. If the direct conversion system is complex and has a quadrature phase splitter for the local oscillator and two good mixers, and a computer system with very low noise wide dynamic range A/D conversion and enough computing power to process the two quadrature signals, it can be pretty good.

That is, of course, nothing at all like a regenerative receiver or a simple direct conversion receiver followed by an audio amp.

My bet he was asking about a simple direct conversion receiver with a local oscillator and a single mixer compared to a simple regenerative receiver. In this case the answer would be the direct conversion receiver is more complex, and works somewhat better. The direct conversion would mainly have stability improvements with less oscillator pulling and better dynamic range, but would be more complicated.

Somehow everyone got off on the track of a SDR system, where a quadrature mixer with low-noise high level mixers and oscillator is fed into a powerful computing system. Of course a $3000 SDR system will outdo a $30 system, but MOST direct conversion receivers are single phase single mixer designs that are not so much better than a regen receiver except perhaps for stability and dynamic range.

73 Tom
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WB6BYU
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« Reply #5 on: August 07, 2010, 09:29:44 AM »

Quote from: W8JI
My bet he was asking about a simple direct conversion receiver with a local oscillator and a single mixer compared to a simple regenerative receiver. In this case the answer would be the direct conversion receiver is more complex, and works somewhat better. The direct conversion would mainly have stability improvements with less oscillator pulling and better dynamic range, but would be more complicated.


The big advantage of the direct conversion receiver, especially for SSB, is stability and the ability to calibrate the dial.  Some
really cheap DC kits may not even be very good in that respect if the VFO isn't designed well.

Regenerative receivers can get more gain out of the detector stage, which sometimes means you can hear more signals
without an audio amplifier stage if you have high-impedance headphones (which most people don't.)  Otherwise you still have
an amplifier in either set.  And the good regenerative receivers separate the detector from the Q-multiplier, and so aren't
that different in parts count from a direct conversion receiver.


If you like the excitement of making something work, there is something to be said for the two-handed tuning of a
regenerative set for the thrill of being able to pull in a signal out of the noise and peak it for good reception, even if
you don't know exactly what frequency it is on.   For just tuning across the bands and listening to CW and SSB
signals, the direct conversion receiver is easier to use without having to work hard to pull in each signal.

So it all depends on the experience you want to have with the receiver.
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NOTBOB
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« Reply #6 on: August 08, 2010, 10:32:26 AM »

Thank you all for replying.  I appreciate your taking the time and providing some great information.

nb
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W9OY
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« Reply #7 on: August 08, 2010, 12:13:26 PM »

My guess is you won't be very happy with either.  Having something that sorta "works" is not the same as having something that works well.  There is something to be said for the learning experience of building your own, but a cheap simple receiver is not how to start your radio career.   

If you want a simple CW radio look at an Elecraft K-1.  If you can find one a softrock receiver by KB9YIG is a very good place to start.

73  W9OY

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WB2WIK
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« Reply #8 on: August 08, 2010, 05:48:39 PM »

Unless you're intent on homebrewing the receiver (building it yourself, from scratch) I'd go for a cheap superhet receiver.

Radio Shack has the Grundig G5 on sale for $49 right now, and the damned thing actually works pretty well (tried it).  It's stable, works on SSB-CW, and has a tuning rate that's acceptable for those modes.

It's also sensitive enough to receive W1AW on HF from here in Los Angeles, nearly 3000 miles away, using its telescoping whip antenna...20m earlier in the day, 40m later in the day.

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VE3LYX
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« Reply #9 on: October 30, 2017, 05:53:52 AM »

I would take issure with rating a dc above a regen. A regen hears more. Had a built in bfo. If it isnt stable it is your fault as the same principles apply. Whether you are building a lo for a fc rx or a regenerative detector. And BTW s good regen does NOT require two handed tuning. In factoften once set the regen rarely neefs retouching when operating in ham bands. Have hete both hollow state and solid state regens. Also have two dc rxs. They are not even in the ball game.
VVE3LYX don
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OZ8AGB
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Posts: 334




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« Reply #10 on: October 30, 2017, 07:30:17 AM »

While you build a radio these radios are absolutely free:
http://websdr.org/
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KC4ZGP
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Posts: 1637




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« Reply #11 on: October 30, 2017, 10:25:24 AM »

Hmmm.

The top of the line transceiver Alinco SR-8T will do.

K0UA would suggest the Yaesu FT-891 but he always says silly things. Just humor him.

Kraus

« Last Edit: October 30, 2017, 10:30:17 AM by KC4ZGP » Logged
N4UE
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Posts: 705




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« Reply #12 on: October 30, 2017, 01:47:33 PM »

NB, there are a lot of great suggestions here.

I'm unclear if you desire to build your own or have a limited budget.
In any case, what about an older SW receiver?
I have more than 100 receivers here, way more, from the very latest to some pretty poor ones.
I find they all have their own 'charm'.

One older radio that surprised me enough, that I ended up with more than a few, is the Realistic (Radio Shack) DX-150/160 series of receivers. Yes, you need to get one that works correctly, but I keep one in my shop, just to listen to the ham bands, and what there is left of SW broadcasting. ha ha

Although I've aligned all of mine, they were pretty good as purchased.

Before I get flamed for suggesting these radios, you can acquire one very cheaply and there's a lot of support out there.

Radios like the R-390A are vastly superior, however, they are very expensive and complex. No tubes to worry about in the RS radios. Since you are here on eHam, go to the 'Reviews' section and spend some fun hours reading the 'Receivers' section, general coverage and/or amateur type.

While I love my Collins radios, etc, it's all about ....

"bang for the buck"

Welcome to the hobby, friend.

ron
N4UE
hamming for 56 years
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K1ZJH
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Posts: 3308




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« Reply #13 on: October 30, 2017, 03:02:57 PM »

After the war, many hams used old WWII  RAL and RAK receivers for CW, with excellent results.  They were the ultimate HF regen.



http://www.virhistory.com/navy/rcvrs/rak-ral.htm
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K4SAV
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Posts: 2388




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« Reply #14 on: October 31, 2017, 06:51:09 AM »

Answering the original question is probably not necessary since the question is 7 years old. 

But if you have something that present readers would be interested in, have at it.

Jerry, K4SAV
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