Tube type synchronous detectors

[vincent]

Yes, as you said, it’s a waste to use the 7360 in an unbalanced configuration (one plate and one deflector grounded for RF), why Rycom used it in this way? I don’t know. Of course using the 7360 balanced would make life more complicated, a center tapped IF transformer for the deflection plates, a center tapped Audio transformer for the plates……..and more expensive!  But the R1307/GR was a high class professional test Instrument, so why?  This receiver should be from the early sixties (or late fifties) at that time the 7360 tube was in vogue……. 
An Octal beam deflection tube was the US Navy CKR 1636 from RCA that was used in a radar. In the mid thirties a Danish engineer invented the Renode tube which was a sort of beam deflection tube, both derived from the CRT.

[w1vtp]

I confess!

I have given in to the lure of an appliance.. I ordered the rackmount version of the Sherwood Engineering Incorporated SE-3 MK IV adapter today.

<snip>

Patrick

You will like it.  I actually prefer it over my Flex 5000 SAM performance.  Once one gets over the extreme price, the rest is a pleasurable experience.  I use mine with either my SX-73 or more likely, the SP-600.  The only fault I find is not related to the SE-3 but with the fast AVC of the receivers.  I am spoiled with the adjustable AVC timing on the Flex (and my FT-301). I don't like the extreme noise between transmissions.  Some day, I will play with the AVC timing circuits on these receivers. - yet another post-retirement project.

Al

[Opcom]

Wow - the 1636 is  beautifully made tube and I bet it wasn't cheap! I see none for sale with a quick search.

On the AVC and SE-3, The R-390A has a very slow setting but since it is not a SSB rig, my concern is that the AGC will do nothing. I know that when using the BFO on the R-390, the SSB is frequently distorted and I have to ride the RF gain control to properly listen to SSB on that set. This issue also applies to the SX-28. The AGC in that one comes from its own transformer and it seems very narrowly tuned to the place of the carrier. The SX-28 has also an AVC circuit, but it mostly controls the output volume. I'll have to try it all before judging. The guy at Sherwood said he didn't have any built up, so it is taking a bit for mine to show up here but I can wait a few days. He said he would include the schematic upon request with the new unit. I asked about that should I ever need to service it out of warranty. He also said it is all analog unless one considers a PLL to be digital. That is what I like, an analog path for analog signals.

I have not warmed up to DSP products because I don't know, and am not informed by the manuals, what is really being done in each product (I understand the principles), but I like ASP no matter how many tubes (or ICs) it takes.

[Opcom]

The SE-3 arrived today. Very nice looking. Need to find a socket for the necessary 24V power as it is a kind of smallish 4 blade Jones connector (I would think a socket would have come with it for the price. Might just use clip leads.) and need to make up a cable for the I.F. The Schematic will take some reading.

[w1vtp]

The SE-3 arrived today. Very nice looking. Need to find a socket for the necessary 24V power as it is a kind of smallish 4 blade Jones connector (I would think a socket would have come with it for the price. Might just use clip leads.) and need to make up a cable for the I.F. The Schematic will take some reading.

It didn't come with a wall-wart PS?  Mine did

I just checked the web site - you need to call Rob up.  It comes with a 20 VAC wall wart and a connector.

Al

[Opcom]

Having read that, I searched the box and found the wall wart and with attached connector. I must have missed this before. The packing material is peanuts and the box is quite large because I ordered the rack-mount model so that's why it didn't turn up before. It won't be long before I get to try it out!

[w1vtp]

Having read that, I searched the box and found the wall wart and with attached connector. I must have missed this before. The packing material is peanuts and the box is quite large because I ordered the rack-mount model so that's why it didn't turn up before. It won't be long before I get to try it out!

WHEW!  Glad I was helpful.  You are going to LOVE this unit.  Sure it is pricey but the quality coming out of that detector is so good you are going to forget about using the receiver's inboard AF.  I'm assuming you have a good amp and HIFI speaker to hook it up to.  Do you work the east coast much and if so, what band?

Al

[aa5wg]

I saw this PDF article on my Destop.  I must have found it on another hams web site.  It is titled "The Synchronous Detection Process" by W3DUQ.

Open up the attachment and and the third page down (listed as page 6) is the article.

Chuck

[Opcom]

Having read that, I searched the box and found the wall wart and with attached connector. I must have missed this before. The packing material is peanuts and the box is quite large because I ordered the rack-mount model so that's why it didn't turn up before. It won't be long before I get to try it out!

WHEW!  Glad I was helpful.  You are going to LOVE this unit.  Sure it is pricey but the quality coming out of that detector is so good you are going to forget about using the receiver's inboard AF.  I'm assuming you have a good amp and HIFI speaker to hook it up to.  Do you work the east coast much and if so, what band?

Al

I have a great hi-fi, a Stromberg-Carlson 30 watt integrated hi-fi amp in a large wood console with a 12" "Custom 400" coaxial speaker.

I don't get much contact with the coasts. I am told the ol' 4-legged dipole shoots North and South mostly. I am also told that if I swap the legs around, that it will fire more E-W.

A plan drawing is attached that might explain it.

The legs vertically are at about a 45 degree angle sloping down from the feedpoint at 55FT toward the ground. Each is about 63FT long. Before they get there, there is guy rope and each rope's terminus is about a 10-15FT tall pipe. I am guessing the ends of the wires are some 20+FT above the ground.

The feedpoint where the V's of the legs are joined is at the 55FT level. I can't get to it easily and I am afraid to send a weak link like a relay up the tower.

If it is true that switching the electrical direction of the vee would move the 'beams' 90 degrees, then I was thinking of running another OWL up there so there would be two feedlines. Reversing polarity on one would switch the beam. The relay could be in the shack in the ATU enclosure.

Seems simple but will it work? Anyway that's the dope on why I don't do the Coast. I get good reception with the gulf and north through the Dakotas.

I saw this PDF article on my Destop.  I must have found it on another hams web site.  It is titled "The Synchronous Detection Process" by W3DUQ.

Open up the attachment and and the third page down (listed as page 6) is the article.

Chuck

That's the W3DUQ design, with many tubes!

[Pete, WA2CWA]

I saw this PDF article on my Destop.  I must have found it on another hams web site.  It is titled "The Synchronous Detection Process" by W3DUQ.

Open up the attachment and and the third page down (listed as page 6) is the article.

Chuck

The link was posted April 12th, in this same thread. No mystery

[aa5wg]

Okay.  Yes, there are lots of tubes.
Chuck

[Opcom]

I like it, and if I could make the time I would like to try building something like that. Building receiving equipment that gives professional results is much more challenging than building the same level of transmitting equipment.

I'd thought there were some simpler tube type synchronous detectors out there but after a couple months of reviewing the materials and coming to understand the functions involved in the methods, I can only submit the following theorem:

"There is always a positive correlation between the number of tubes in a circuit and the degree to which perfection is approached".

Unfortunately this is not a linear relationship. It is more like P=nT^2.

[Rob K2CU]

The W3DUQ unit looks really neat!  Functionally, it looks just like the Binaural DC receivers of late but adds an audio phase shifter so that you can get either USB or SSB without the binaural function.

A phasing type SSB receiver works like a phasing type exciter, but in reverse. You down convert to I and Q audio signals with a pair of mixers that are driven by quadrature LO's. The I and Q signals are then sent through phase shifter networks that have the difference between them be 90 degrees. You then either add the outputs or subtract them to produce either USB or LSB audio. In the W3DUQ unit, the I and Q signals are also made available for stereo headphone output. Spatial ear/brain processing is how the signals are separated....like listening to one conversation in a room of people. W3DUQ also provides a means to phase lock the I/Q LO to the incoming carrier if present. Less clearly understood is the SSB mode where the LO frequency tracks an average DC component from the mixers.

For applications at a fixed frequency, i.e. a detector at the end of an IF strip, you could use a crystal to hold the LO on frequency for SSB. In a PLL, a crystal controlled VCO does allow pulling, but has a very tight lock-in range, as expected. The Signetics PLL ICs of the seventies showed such a scheme in an application note. In the tube world, this type of I/Q demodulator with a crystal stabilized oscillator was used in tube type color TV sets for the chroma demodulation.

 

[Opcom]

I remember the TV circuits. The crystal was pulled during burst and was expected to remain close for the rest of the line, so it only had to stay put for 63us. If the oscillator was out of alignment there would be vertical bars of wrong color positioned across the screen.