Sync AM detector board offered for sale

[w1vtp]

http://www.valveradio.net/index.php/en/home/radio/synchronous-detector-module.html

I had to "X" out a popup but interesting read at least

Here is a YouTube demo

http://www.youtube.com/watch?v=tKECG8nkzu4

I did not see a price

Al

[Opcom]

A product of the Voice of Revolutionary Vinco! I swear it is the same announcer.
http://www.bunkerofdoom.com/vorv/index.html

[flintstone mop]

We will have to do some digging...He mentions he sells on eBay. The detector is impressive in its performance. The AM stations in Europe sound pretty clean and smooth.
Fred

[N0WEK]

We will have to do some digging...He mentions he sells on eBay. The detector is impressive in its performance. The AM stations in Europe sound pretty clean and smooth.
Fred

It says right on their website that you have to email to arrange to buy it and get a price; a strange way to market it. It limits their market and make a whole lot of extra work for them to respond to shopping around requests.

I looked on Ebay and found nothing as did a web search.

[W3RSW]

Perhaps just a directed scam for your  compandered wallets' yearning for high fidelity AM.

Beware  

[KD6VXI]

The popup shows its on a free hosting site.   The contact page doesn't work.

Website shows copyrights since 2012.

Something isn't adding up.

--Shane
KD6VXI

[K4RT]

The video would have been more helpful for me if the audio were of better quality, and pauses during narration were longer to better evaluate the audio in each mode.  It would be interesting to see some real-time comparisons, on a scope for example.

[w1vtp]

Shane

The "Contact us" page loaded and acknowledged my request.  I used a bogus email because I'm not personally interested since I already have a SE3.

Maybe your browser settings or AV settings are  getting in the way.  The popup never loaded since I have an effective popup setting turned on.

[flintstone mop]

The video would have been more helpful for me if the audio were of better quality, and pauses during narration were longer to better evaluate the audio in each mode.  It would be interesting to see some real-time comparisons, on a scope for example.

None of these demos for Synchronous detectors picks the worst situations. Someone flabbering away on a shortwave station, voices only, no music, is about the worst possible demonstration. Tune into a station playing music with severe selective fading distortion, and then let's hear what Synchronous detection can do.
Most demos are receiving strong signals and not being put to the ultimate test. The Europeans still enjoy many high power short wave stations.
My ultimate test would be receiving WBCQ playing music. There are times that the signal will hang in the maximum distortion of music during the fade. I will guess, and say, the sky wave, and possible ground wave are colliding at the RX antenna. I have never been able to figure why it is so bad on their frequency. I'm too close to the station? Their antenna is too low  to the ground?
I'm sure there was some engineering needed to prove to the FCC that they were intending to hit Central America as their target area. 10dB gain directional antenna is part of the equation. Height above ground is the mystery to me.
Sorry if the last few sentences were a slight hi-jack. But it seemed that the detector in the video was as effective as an SE3 or the SAM mode in my Flex SDR software.
The SE3, supposedly, was the Cadillac of detectors. The designer never revealed what he was using in his process. He would send schematics to those that requested them; but they had to promise not to publish.
Fred

[w1vtp]

The video would have been more helpful for me if the audio were of better quality, and pauses during narration were longer to better evaluate the audio in each mode.  It would be interesting to see some real-time comparisons, on a scope for example.

<snip>

Sorry if the last few sentences were a slight hi-jack. But it seemed that the detector in the video was as effective as an SE3 or the SAM mode in my Flex SDR software.
The SE3, supposedly, was the Cadillac of detectors. The designer never revealed what he was using in his process. He would send schematics to those that requested them; but they had to promise not to publish.
Fred

(quote emphasis, mine)

That's Rob Sherwood, NC0B (  http://qrz.com/db/NC0B  )  He was very helpful to me while I was setting for my SE3.  I don't fault a guy for protecting his business by not sharing information that is not needed for sale or support of a product he sells.  I think part of Rob's business model was not only manufacturing the SE3 but repairing it.  Perhaps now that he is no longer manufacturing the product he might be willing to share what he does in that black (err, grey) box.  But then, maybe he's still supporting it by repairing ones that fail. I hope so.  

Central Electronics did more or less the same thing by encapsulating their broadband finals in their 100V / 200v tube finals.

This whole idea of an enhanced carrier into an appropriate mixer as a detector for an improved AM detection circuit is not a new one.  It's up to the potential benefactor as to whether or not he wants to go to the bother to implement the concept albeit spending the bux or building the detector.

Al

PS:  I see from his DOB he's 67.  That certainly qualifies him for slowing down from a self-employment situation  

[N8ETQ]

  Back in the mid '80s I guess, some Ham Rag
published an article on Synch Detection that
included a schematic for these. They worked
really well. I made one for both a 455kc IF
and one for 500kc IF.

   They were pretty simple with a VCO running
at the IF freq of your choice and a couple
of TTL chips 7474 and 7404 to square up the
VCO signal. A couple of MC1496 Mixers and a
bunch of OP Amps. The adjustments were a little
touchy but nothing you couldn't overcome.

   I guess I lost the data on them, I hooked one
up to my R390 IF a few months ago and could hear
the detected signal however it wouldn't Lock
up on it.

   Would like to get them going again if anyone
has the article or can recall where it was published.
The "Strapping" local Carrier and product detector
really made for sweet sounding AM. Guess it takes
less carrier for the VCO to lock than would be
required for proper demodulation of the side bands.

Thanks

/Dan

[KA0HCP]

JUL 1993 - QST (PG. 28)
Synchronous Detector for AM Transmissions, A
Author: Vermasvuori, Jukka, OH2GF
Article: QST Archive [PDF]
Keywords: SYNCHRONOUS DETECTOR AM TRANSMITTER CONSTRUCTION HOMEBREW

[Steve - K4HX]

The W9GR article came out in the 80's IIRC. It was not simple though. Still one of the best designs I've seen.

[KA0HCP]

W9GR published a DSP filter design in QST in Sept 92, but I do not find any designs by him for synchronous AM detection.

[Steve - K4HX]

It wasn't in QST. I think it was Popular Electronics. /foggy memory

[N8ETQ]

     I don't think it was QST as I never got that,
one of those Wayne Green Rags, Maybe 73?

/Dan

[WQ9E]

Popular Electronics April 1982, I attached a PDF to this post.

[N8ETQ]

   Hey Rodger,

      Yes that is very similar to what I have but
mine uses the MC-1496 as the phase det. and another
one for the Product det. But I do recall reading that
article!

   I attached a close up of the other unit I made and
it's easier to see that it uses 5  741 op amps, the
2 TTL chips and the old style round can MC1496's.

   The only adjustments are the 5 pots to the left
of the shield between the VCO and the rest of it.
The 2 pots close to the shield are for the VR devices
and the three 20 turn jobs I put in the loop filter to
"Pre-Adjust" the VCO for USB/LSB and AM.

    I'll have to play with these things if I can get
caught up on some other projects. Your article should
get me on track to start to reverse engineer the thing.

    Your article is from the right "era" for sure, and
I think the authors concept was the MC1496's being
"Clean" phase and product detectors.

    These things worked VERY well and I must have stopped
using them when I got my CV-157 but it too had some issues
(like the motor tuning) and the 100hz carrier passband
that made it tough to use in a round table. It was always
lost.  I still have the 157.

Thanks again Rodger and everyone else who spent time
searching.

73

/Dan

[WQ9E]

There was an update to the PE circuit. 

[Steve - K4HX]

The W9GR has two things I haven't seen in other designs.

1. Two loop bandwidths - one wider for when the loop was unlocked providing quicker loop lock and less critical tuning of the associated receiver; the second narrow for when the loop was locked providing noise rejection and resistance to loss of lock during fading.

2. A square-law or diode detector that was automatically switched in when the sync detector was unlocked and switched out then the sync achieved lock (all seemlessly). This trick removed the characteristic whooping heterodyne as the sync detector achieved lock or as one tuned across the band.

[wd8das]

Back in the 1990s I offered an add-on AM Sync Detector kit for 400 - 500 kHz IFs based on the sync detector design in the Sony ICF-2010 receiver.  It included "switch-to-envelope-detection-when-unlocked" so tuning was smooth and heterodyne free.  It also provided separate demodulated sideband outputs, so you could listen to whichever sideband sounded better.  They worked great and for a further decade I was addicted to listening to AM on my sync detector and sold a fair number of the kits.  It is highly effective on selective fading and by offsetting the tuning to one side or the other you could obtain more interference resistance and higher fidelity.

Unfortunately the Sony AM stereo IC and precision phase shift network became very expensive and finally unobtainable - maybe they were resisting my attempts to deplete their 2010 receiver spare parts inventory.  -grin-  Those parts were never offered for use in non-Sony products. 

I recall building a sync detector with the Motorola AM stereo decoder chip as well - it worked but didn't have the same features as the Sony.

Steve WD8DAS

[WZ5Q]

Howdy Steve,
I had one of your kits and it worked great. Thanks for taking the time to make it available to us.

I had experimented with allot of different AM Detectors and detector diodes in the past looking for the best fidelity. The reason I decided to try your synchronous design back then was the selectable sideband option. I had your kit grafted into my receiver along with other detectors for comparison testing.

After many months of listening & comparing the different AM detectors, I discovered that for my tastes, the Germanium Diode Envelope Detector had the most Fidelity and Depth of Emotion with the Infinite Impedance Detector next in line. I preferred to listen to the Germanium Diode detector on strong signals, while for weak signals or signals with interference problems, the Synchronous Detector shined.

I did notice the Synchronous Detector had a low frequency roll off compared to the envelope detectors. I could never find the reason why and surmised it was just an inherent design of the Sony chip itself. Has anyone else noticed this low frequency attenuation on any other Synchronous Detector design?

Take care,

[flintstone mop]

There has been mentioned a couple of times about product detectors. Reading deeper from responses here in AMFONE and Google; it seems that the product detector is a lot better demodulating the AM envelop compared to a Diode. But where to find a Hi-Fi product detector? I bought a product detector, claimed to be hi-fi for my R390A, and it was really nice for SSB. But it was not hi-fi audio. Telephone quality audio to be more exact.
Fred

[N8ETQ]

  Hey Fred,

  Probably have to roll your own, In theory the
PD should respond to inputs only limited by the
pass band of the IF filters in the rig and of
course any restrictions in the AF pass band.

  I had success getting one of my HB Synch det.
going last week and although my shack audio system
has fallen into disrepair it sounds real good using
a pair of Audio Technica Headphones. I have decent
audio amp in the garage I want to get in here and
get my audio system going again.

   If I can accomplish that in a timely manner and
find a couple of cables I can make some better A/B
recordings of the sounds coming out of the product
Det. Vs. the diode load on my 390A.

   Here is a schematic of PD that uses a MC-1496
with a single rail supply. The one in my unit uses
a +/- supply.

/Dan

[Opcom]

Popular Electronics April 1982, I attached a PDF to this post.

I love the LDR AGC system, beautiful and smoooooth. I also love Sherwood's modern design, which is very analog. I'd like to study the schematics for the ones in the pictures as well as the 1980's kit mentioned.