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[WA1GFZ]

Perseus is an interesting box....

[WA1GFZ]

Alberto's latest sync detector is very cool. A couple seconds to lock then a second or so to hold phase. phase meter is very cool to watch as an am signal is pulled in. all automatic

[VE7 Kilohertz]

 Three of Tony's kits are on their way to me next week. Now to find time to build them...

What is Perseus?

cheers

Paul

[WA1GFZ]

Perseus is a preselector directly into a 65 Msample A/D. I think it goes for about $1100. Made in Italy so you know it is good. This is the next step beyond Flex.
No more worry about a DDS with spurs or a PLL with phase noise. Just one  crystal clock frequency that needs to be clean without jitter.
HPSDR has one coming soon with a 130 or 170 msample A/D and 1/2 watt exciter module later. Also a VK is working on a spectrum analyzer front end for it.

Flex 5k will be old soon. Save your cash it is over priced anyway. Get a used one cheap in a year or so.

[WA1GFZ]

I would consider getting Perseus if I wasn't dialed into HPSDR. The good thing is you get a packaged product good to go. too bad there is no TX.

[VE7 Kilohertz]

Frank, I'm just not sure that I see any advantage in producing an output signal from SDR/DSP. I can see that the raw RF output from the DA converter would be very clean but that's a VERY PW level signal. Put that through a standard SS linear setup and all the normal distortion products reappear on the signal. Maybe a big class A tetrode/pentode 'tube with handles' at this low drive level would reproduce the original signal with little distortion added but that's a very pricey option?

I was thinking the same thing Mack, but being able to process your audio in DSP on your mega computer would be as fun and much cheaper than an Optimod 9200 or Omnia box. I have sampled a slew of buffers, drivers and linear HF amps, in the .5-5 watt range from various mfrs to allow me to use the HP 8640B as a low level modulated VFO, step it up to something usable by my various linears, TMC-PAL 1K, or Collins HF-8020. They only need 100mW I think. Actually, maybe I don't even need the buffers come to think of it. I think I already had the PAL working with the 8640 a few years ago. Man, how the brain fades with time.

Gates had a low level modulated TX back in the late 60's that used a 4CX3000 or similar, with low level mod. Looked like a washing machine and worked and sounded about the same. 

Anyway, confusing things here.

I am still looking for an external sound card, the softrocks are on order and I will play with those for a while and get used to the SDR way of thinking. I am looking forward to connecting to the ouput of the 6790 to see if the synch detection can be improved.

keep up the good work fellows.

Paul

[Steve - WB3HUZ]

 

Frank, I'm just not sure that I see any advantage in producing an output signal from SDR/DSP.

I do. With SDR you can transmit nearly ANY mode/emission, even new ones that come along, WITHOUT any physcial/circuit redesign or modification. Just add the code for the new mode and off you go - transmit and receive. True SDR will allow you to download the code on the fly (it could be totally transparent to the operator). Your cell phones already do some of this.

If you aren't interested in any new modes, then the above probably won't be seen as an advantage.

Put that through a standard SS linear setup and all the normal distortion products reappear on the signal.

No need to do that. Low distortion amp designs have been around for decades. Think out of the box bro!

[WA1GFZ]

I & Q with a clean source you can move the world.

[WA1GFZ]

Sometimes I wish I was a software puke.

[KF1Z]

From that fasion description...

Einstein must have been a computer geek.... albeit a bit before his time (pun intended)

[VE7 Kilohertz]

MAck,

On the 6790, check the NiCad battery on the right side of the chassis. It is soldered directly to the board and is most likely leaky or otherwise defective.  I replaced mine and all problems went away (Bite wise).

GL

Paul

[Steve - WB3HUZ]

I wasn't thinking of standard amateur-grade amps. With DSP, predistortion and other low IMD techniques can blow away any amateur stuff. Hams are just too lazy or dumb to do it, and the manufacturers are too cheap.

I do. With SDR you can transmit nearly ANY mode/emission, even new ones that come along, WITHOUT any physcial/circuit redesign or modification. Just add the code for the new mode and off you go - transmit and receive. True SDR will allow you to download the code on the fly (it could be totally transparent to the operator). Your cell phones already do some of this.

Put that through a standard SS linear setup and all the normal distortion products reappear on the signal.

No need to do that. Low distortion amp designs have been around for decades. Think out of the box bro!

Steve, even with the best of the breed of the newer solid state amps, linear amplification of a voice modulated signal always adds distortion products. I've never seen a spectrum display of the output of one of the newer generation SS amps using the standard two tone SSB signal source that impressed me greatly. Big tetrode/pentode ceramic metal tubed class A amps do impress me with their ability to amplify with near zero distortion. But of course the efficiency sucks, nothing like watching 5-10kw of constant plate dissipation making nothing more than heat 90% of the time!

Steve, I'm "thinking out of the box" here but trying to keep things in the vein of receiving only at this time. Adding new modes should be a snap with SDR. Trouble is that I have not seen any of the newer proposed modes that are anything to get excited about, most look like train wrecks about to happen to me.

Mack

[WA1GFZ]

Don't mount the new one on the board. Remote it so if it leaks there will be no damage, put it in something that would contain a leak. Heck even a protable phone battery should work.

[VE7 Kilohertz]

Don't mount the new one on the board. Remote it so if it leaks there will be no damage, put it in something that would contain a leak. Heck even a protable phone battery should work.

Exactly what I did. A little Panasonic NiMh and it has been going for over 3 years.

Gld you found the problem Mack.

Let me know what RX's you have. I too am always looking for new play toys.  I don't have any Harris or WJ yet.

Cheers

Paul

[VE7 Kilohertz]

Interesting Mack,

Sounds a lot like my line up (of days gone by) .

Collins 51J4
R-388
R-390 (non A)
Collins HF-2050
Racal 6790, 6793, 1792
SP-600 
R-390A
Hagenuk R1001

I love receivers, and playing with and tweaking them. I am no where near where Frank is for technical tweaking, but do understand it all...just can't find the time to do it all. Seems paying the bills keeps getting in the way.

Paul

[WA1GFZ]

Hey Paul,
You have 10 and I have 10 so we must be in the same boat. I have less part numbers though.  Maybe more spare parts though. The only other analog RX I would consider is the Harris RF590A. I would love to drop the 590 first IF and second IF into a RA6830. Or the 6830 first mixer and sync detector in the 590.

[WA1GFZ]

Mack,
How about sharing the R8 sync detector schematic with me. I've never seen it or used it but hear it is a good one. What WJ RX had a sync detector?

[WA1GFZ]

I don't know of any analog WJ with a sync detector. Dallas Lankford did a good article on modifing 6790 audio and AGC. I found Racal sets their audio levels kind of high. This causes the audio amp to saturate. I crank audio levels down until they are just high enough to pass bite. They sound a lot better there. The Racal sunc detector is quite simple. Carrier is derived form the FM limiter / demodulator fed into the LO of a 1496. I have found the RF level into the 1496 kind of high so I put a filter module between the IF and detector module in the hot rod. The lock range is very wide on this detector so have considered adding a filter in the 1496 LO input. There is no PLL to lock up so audio comes out as soon as there is a signal present. The filter module has almost 20 dB of loss and it did not change sensitivity of the radio. It is a lot quieter with the filter. Cubic has the same high gain ahead of the detector. there must have been some design reason for all this extra gain since these receivers were both used in TCI DF systems. 
I'm on vacation this week and next and hope to concentrate on transmitters.

[VE7 Kilohertz]

Seems I have missed this thread for a few days and got behind. 

Mack, the 2050 manual has landed on the coffee table but has yet yo be read. I don't know if it has a synch detector in it, although one would assume to.  The RX works great at low level signals and pulls them out of the noise. It does not however sound very hifi, with only 6KHz as the widest IF.

Mack, sounds like you operate like me. I never pay full value or buy perfectly working units. Always something wrong with them at a bargain. Fix, use, sell (not) or keep (yes).  The 2050 was a prime example. Can't remember what I paid but at the time ebay ones were fetching $2K. Think this one was $600?? not working 100%, wouldn't pass the BITE.  Without a manual, I started digging into it and found a bad contact on one of the cct brds in the front end, a couple of shorted tantalums on various boards. About 6 hours work and it was back on its feet and it has been 100% ever since. Although it stil fails bite once in a while on power up but I think it is just dry caps in the supply.

Frank, yes, the 590A is still on my wish list but haven't been able to find one (reasonable). oops, realized i missed the Cubic 3030 in the last post/list. beat ya Frank :-)

Mack, the Hagenuk R-1001 is a very nice mid/late 80's RX. It has very nice sound to it, sensitive and 3 or 4 IF filters. It is all thru hole cct brds mounted to a rear back plane. I managed to get mine with service manuals but again, haven't had to do much to keep it working.

I'll try to find a pic of it.

Synch detectors. I have many parts that I have acquired over the years, including the old Sony Stereo AM chip set which was used for synch det. in an old QEX or article. Also have the ADI AD-607 eval board which will make a nice synch det.  ARG>>>  Explorer is doubleing all my typing now and I can't read a thing.

more on next post.

Paul

[WA1GFZ]

Well Paul I forgot the 6830 at the beach QTH so we are still even. Yes the Racal isn't a true sync detector but more that the typical radio. I once considered driving a pll with the limiter amp output but DSP is so much easier.
V2-CD  6AQ5 mod almost done. Man they stuffed the audio section in a small place. I take surface  mount components under a microscope over point to point any day 

[VE7 Kilohertz]

Yes the Racal isn't a true sync detector but more that the typical radio. I once considered driving a pll with the limiter amp output but DSP is so much easier.

Exactly what I was planning. I found some of my PLL chips this AM. NE564 and a few other more exotic ones. I may still try it although time and workspace are limited these days. Not sure I want to start getting into the 6790 again. It is working 100% now.

Mack, did you get yours fixed?

Paul

[WA1GFZ]

I would use a XOR gate as a phase detector driving a VCXO because the default or no input PLL frequency is in the center of the tuning range. All is interesting but the DSP is so much easier.

[WA1GFZ]

I'll take surface mount under a microscope over working on a V2 audio section any day. But it is fun to drive 807 grids to positive 20 volts and watch the monkey swing. poor screen grids are yanking 50 mills peak so they are begging for mercey. I do let the voltage dive at 50 so they don't glow.
I don't care for Tony's transformer design. Too many turns. I do 3 turns trifilar #30 on a 2 hole type 43 bead.

[WA1GFZ]

Tony is stuck on low perm cores. You could use a dozen turns trifilar on a ui 125 perm 3/8 or 1/2 inch toroid. Type 43 material even less turns. Even type 77 would work on 455 khz. the Best way to test is is drive the 50 ohm side with a signal like the Softrock LO and look at the secondary with a scope. Hang 200 ohms noninductive across the secondary. The transformer is 1:2 step up so you should see just under double voltage. 1 dB of loss is ok.

[VE7 Kilohertz]

Hi Guys, just getting back from Christmas trip.

No, I haven't seen the kits yet Mack. Waiting.......

Well, SMT work is no problem for me, although it is nerve racking at times, especially when you drop something into shag carpet. I was production manager for a large SMT line for a few years and acquired a lot of skills and equipment (soldering, tweezers, solder magnifying lamp etc. ) The magnifier is the most important tool for me.  ;-)

Frank, yes, I remember now that the holes on the 6790 were just the right size. More likely to hold the parts while going thru the wave solder machine. You have a V2 preamp? Cool. Wanna trade for something?

More later. It's breakfast time for the boys.

Cheers

Paul