Sherwood Sync

[KC9GMF]

I've had a SE-3 since '99

Used it with many receivers, my favorite combo is SE3 looped through a SX28A driving a R42 spkr, bypassing that crappy detector in the 28A. the sound was AM bliss.

Tom

[w1vtp]

It's not so hot for receiving Timtron's SBE, either.

YUP!

[kg8lb]

It's not so hot for receiving Timtron's SBE, either.

  Never really needed to. 

[aa5wg]

Hi to all:
Can the current model of the SE-3 be used with SSB?  I would be using the SE-3 with the Drake R4C (and maybe someday with a Hammarlund HQ170A-VHF or HQ-180A).

I will be using the SM0VPO 4 watt audio amp (with some W9AC changes) as a replacement modification inside my R-4C receiver.  (I have not made this mofication yet.) I have heard good things about this audio modification for the Drakes.  It is a low noise audio amp that is suppose to sound great and get rid of the Hiss.

Does the SE-3 have an audio amp inside it?  
Chuck

[k4kyv]

Hi to all:
Can the current model of the SE-3 be used with SSB?

Yes. The "SSB" mode toggles the BFO to manual control instead of using the PLL to lock it onto the AM carrier.  You use it just like you would a regular BFO in a traditional receiver.  The product detector in the SE-3 works much better than the crappy stock one in the 75A-4. I never knew how good a SSB signal could sound until I started using the SE-3.  Of course, the typical tin-can hammy hambone SSB audio still sounds crappy, but many of the newer slopbucket rigs are capable of sounding pretty decent if a high quality microphone is used and everything is adjusted properly.  Some of the ESSB boys (the ones who do it right) sound almost, but not quite, as good as AM.

Does the SE-3 have an audio amp inside it?  

Yes.  It is rated at 5 watts IIRC.  I don't use it in mine.  Instead, I still use the same 10-watt p-p 6V6 audio amp that I have used with the HRO and later the 75A-4, for many years.  I drive it from the headphone jack on the SE-3.  I have another speaker hooked up to the built-in audio, but I still like the sound of my separate amplifier/speaker system better.

[aa5wg]

Hi Don:
"Sounds" like you have great audio.  I do not want to put my new cleaner audio, from the modified Drake R-4C, into a possible slightly noiser audio amp.  I am trying not to reduce audio quality that I worked hard to improve.  I don't want the HISS to return.

I read from Sherwood's web site "an auxiliary ouput is provided for an external amplifier".  This is an audio amp application.

Do you know if this "external" audio amp, that I would provide, is taking its input from the SE-3 built in audio amp or is it taking it from the radio audio amp, i.e. Drake R-4C?

Is there a sepparate audio output jack on the back besides the front audo Jack?

Thank you.
Chuck

[iw5ci]

if you tolerate a pc in your hamshack with 10 $ you can have a if spectrum analyzer a am/fm/ssb/eccss/drm reception with notch noise blanker , knife filters all at your fingerprint.

I use my collins 390 with a 455 to 12 khz converter and the audio is just wonderful, i have a silent PC so i cannot even ear the pc running and there is no interference to the radio at all.

you can also record in digital mode all the receiver bandwidth and so have a perfect record of the qso's.

http://www.youtube.com/watch?v=dISFHDISzPw

[kg8lb]

 All of that stuff is likely  available as a cell phone app as well.  They use a lot less energy, great audio and they can go anywhere with you .   


 

[Steve - K4HX]

You take your R-390A with you?

[k4kyv]

Hi Don:
"Sounds" like you have great audio.  I do not want to put my new cleaner audio, from the modified Drake R-4C, into a possible slightly noiser audio amp.  I am trying not to reduce audio quality that I worked hard to improve.  I don't want the HISS to return.

I read from Sherwood's web site "an auxiliary ouput is provided for an external amplifier".  This is an audio amp application.

Do you know if this "external" audio amp, that I would provide, is taking its input from the SE-3 built in audio amp or is it taking it from the radio audio amp, i.e. Drake R-4C?

Is there a sepparate audio output jack on the back besides the front audo Jack?

There is an auxiliary output at the back of the unit, but the audio level is set to a specific level, requiring a separate AF gain control in the outboard amp.  My amp does not have a gain control, and besides, it is in a separate rack and a volume control on the amp would not be convenient to  get at.  So instead, I use the headphone output whose level is adjustable using the built-in AF gain control on the front of the unit. IIRC, they both come from the same audio source, bypassing the 5W built-in power amp.

[aa5wg]

Don:
Thank you for your input on the Sherwood unit.  This helps.

Has anyone seen or tried this Synchronous AM Detector?

http://cgi.ebay.com/SYNCHRONOUS-AM-DETECTOR-ALL-SHORTWAVE-RECEIVERS-/190528951877?pt=Shortwave_Radios&hash=item2c5c691645

Chuck

[kg8lb]

You take your R-390A with you?

  No, I dumped them when I bought the four R-725s . Don't have a cell phone nor computer in the shack .

[Steve - K4HX]

So you take four R-725s instead. Awesome! How do you clip those onto your belt?

[flintstone mop]

It seems like it would be ok to mention some things I have noticed about sync detectors and selecting USB or LSB.
When listening to music the selective fading distortion is reduced but not eliminated when using a sync detector.............true or false??
With my Power SDR software I can move the "I.F." and only listen to Upper or Lower sideband and the distortion is still there. The Phasing sound and the crunch sound.
Looking very closely to the Panoramic display I can see the modulation with a 'wave' floating through. When the audio is clean, the display is steady. Bass notes are close to the main carrier and the higher frequencies are out towards the ends of the display, depending how much you allow to show in the 'bandwidth' settings of the software.
So the Sherwood eliminates ALL selective fading and distortion?? The audio samples I heard online 'with' and 'without' the sync detector seemed to reduce the distortion. Regular voice is hard to hear this, but music really stands out cuz of the wider bandwidth.
BTW listening to music on WBCQ 5.110, which is a reduced carrier USB transmission, the selective fading distortion is reduced more than the full carrier transmission. But because of the reduced carrier a sync detector becomes mandatory.
Yes, interesting thread........tnx
FRED

[kg8lb]

So you take four R-725s instead. Awesome! How do you clip those onto your belt?

  Asking a question  ?   Wrong answer anyhow .
Here is the scoop for you. With a cell phone you don't need the old school receiver on your belt buckle  
  I wasn't actually suggesting a cell phone. I was using the cell phone analogy proposing a replacement for both a cornpooter and ham radio .        

  The flawed logic that ensued was not of my making .

  73 there, Old Man

[k4kyv]

When listening to music the selective fading distortion is reduced but not eliminated when using a sync detector.............true or false??

True. The  distortion that occurs when the carrier nulls out in a fade is eliminated, but when the null passes through the sidebands, it is kind of like tuning a notch filter through an AM signal.  You can still hear some phase distortion effect, but it is not as devastating as what occurs with the stock diode detector.

The envelope detector in the Sherwood has very low distortion compared to the stock diode detector in the receiver. When receiving a good solid signal with no selective fading, I cannot tell the  difference between envelope and product (sync) detection. But when there is substantial selective fading distortion present the sync mode sounds much better. Also, in the  presence of noise and interference, the sync mode is superior.  When the signal is marginal near the noise floor, the sync mode sometimes pulls an unreadable signal out of the noise and makes it near 100% copy.

The reason for this is that with envelope detection, everything within the passband intermodulates with everything else. That means a noise signal beats with the AM carrier, USB and LSB, and with every other noise signal within the passband. In sync mode, the the only output from the detector is whatever the BFO beats with. The BFO beats with USB and LSB, and with each noise signal, but you don't have multiple noise signals beating with each other, and the noise signals don't beat with USB and LSB or the AM  carrier. So you still hear the noise and QRM, but not all the products of every element of the noise and QRM signals beating with each other and with everything else inside the passband.

With my Power SDR software I can move the "I.F." and only listen to Upper or Lower sideband and the distortion is still there. The Phasing sound and the crunch sound.
Looking very closely to the Panoramic display I can see the modulation with a 'wave' floating through. When the audio is clean, the display is steady. Bass notes are close to the main carrier and the higher frequencies are out towards the ends of the display, depending how much you allow to show in the 'bandwidth' settings of the software.
So the Sherwood eliminates ALL selective fading and distortion?? The audio samples I heard online 'with' and 'without' the sync detector seemed to reduce the distortion. Regular voice is hard to hear this, but music really stands out cuz of the wider bandwidth.
BTW listening to music on WBCQ 5.110, which is a reduced carrier USB transmission, the selective fading distortion is reduced more than the full carrier transmission. But because of the reduced carrier a sync detector becomes mandatory.
Yes, interesting thread........tnx
FRED

[w3jn]

The envelope detector in the Sherwood has very low distortion compared to the stock diode detector in the receiver. When receiving a good solid signal with no selective fading, I cannot tell the  difference between envelope and product (sync) detection. But when there is substantial selective fading distortion present the sync mode sounds much better. Also, in the  presence of noise and interference, the sync mode is superior.  When the signal is marginal near the noise floor, the sync mode sometimes pulls an unreadable signal out of the noise and makes it near 100% copy.

Either way, the sync detector even in envelope mode has much less distortion than the stock AM detector in any radio I have, with the possible exception of my WJ 8716 and WJ 9040.

[AB2EZ]

JN's post brought something up (in my mind... perhaps well known to others) that I had never considered before in the context of AM radio reception:

Suppose one is receiving an AM signal with a moderately strong carrier + noise + interference.

A diode based envelope detector (standard AM demondulator) will respond to the modulation + the noise in both quadratures + the interference in both quadratures.

A combination of a phase locked loop and a product detector (i.e. a sync detector) will respond to the modulation + the noise in the in-phase quadrature + the interference in the in-phase quadrature..

Therefore, a sync detector (working properly) should always produce better signal / (noise + interference) performance.

I agree with JN that my SDR-1000 always sounds better (for the same total bandwidth) in synchronous AM mode than it does in envelope detection mode.

Stu

[flintstone mop]

Thanks Don,
I understand better, from your explanation. There's a lot more going on during the fading process. And maybe with WBCQ being closer North, is more affected by any Aurora activity.

[k4kyv]

A diode based envelope detector (standard AM demodulator) will respond to the modulation + the noise in both quadratures + the interference in both quadratures.

A combination of a phase locked loop and a product detector (i.e. a sync detector) will respond to the modulation + the noise in the in-phase quadrature + the interference in the in-phase quadrature..

Therefore, a sync detector (working properly) should always produce better signal / (noise + interference) performance.

I think you are correct.  With the diode detector, there are an infinite number of "quadratures", since there is no BFO and the detector simply responds to the intermodulation amongst all the random signal and noise elements distributed throughout the entire passband of the receiver.

I have found the same thing as John.  The Sherwood envelope detector is far less distortion-prone than the stock diode detector.

At first, I was a little disappointed, since with good, steady AM signals that quieted the background noise, I didn't hear that much improvement when toggling from the envelope (+) mode to the product (X) mode.

Sometimes I surf the foreign broadcasters in and around 40m during the evening.  Even the strong ones sound better in sync mode than in envelope mode.  I often use envelope mode while tuning through the bands or just giving a quick casual listen, since it is less hassle than having to let the BFO  lock onto each carrier as I tune by.

[K5UJ]

Previously I had concluded I could probably get by without the SE-3 but I did not know about sync. detection reducing the effect of RFI.  I may reconsider now as anything that helps tame RFI in the passband is desirable with the exception of DSP.  I have yet to find DSP that does not introduce distortion.   I have heard that the latest yaesu rig the FT5000 has much improved DSP but my days of buying new rigs are over. 

[k4kyv]

It can make an improvement when the RFI is at the nuisance level; makes the noise seem more "transparent". But it won't help much if the noise is devastating and wiping out the signal.

[KM1H]

Is there an AM detector circuit that is better with a BFO as a quasi sync detector? It seems like if perfection isnt required a simpler (cheaper) circuit will suffice. Ive modified several radios to do the BFO injection into the final IF and the results are quite decent with or without AGC.

[k4kyv]

As long as you can somehow lock the BFO to the original AM carrier.  To get the proper vector addition of USB and LSB, the BFO MUST be on frequency and in phase (or exactly 180° out of phase) with the original carrier. I'm not exactly sure what you mean by a "quasi sync detector".

My very first experience was with a pre WWII HRO.  I changed the BFO coupling cap from about 15 pf to 100 pf to get more BFO injection to the detector, and accidentally discovered that the BFO would brute-force lock onto the AM carrier when I carefully zero-beated. I was astounded at the improvement in reception the moment the BFO  locked on.  The only problem with that set-up was that it was extremely critical. If the HF oscillator in the receiver or the AM station's carrier drifted even a few cycles, the BFO would lose lock. I literally had to listen with one hand on the tuning knob.

A simple PLL circuit might be easy to build and would be a lot cheaper than the SE-3, which has a lot of extra features that are nice, but not essential to the basic function.

[w3jn]

An easy way to phase lock your receiver's BFO to the carrier is just inject a bit IF signal into the grid of the BFO tube.  The oscillator will want to lock on the carrier.  Sometimes just increasing the coupling from the BFO to the IF will do the trick.  Unfortunately this will render the BFO useless for SSB or CW.