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W1ZZZ's new K7DYY Super Senior transmitter!




 
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Author Topic: W1ZZZ's new K7DYY Super Senior transmitter!  (Read 15596 times)
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« on: March 03, 2013, 11:41:23 PM »

Hi Folks!

Peter W1ZZZ purchased a new K7DYY Super Senior Class D AM transmitter to augment his Collins 32V2 and Viking Valiant.

After the order was placed it took a few weeks for his unit to be built. One nice change is that Bruce K7DYY designed a new synthesized VFO that has 1kc steps instead of the previous 5kc steps. Peter received the first of a few of the transmitters with the updated VFO's. The lightweight 2 rack-unit solid state rig arrived last Tuesday and we installed it that evening. All tests were successful, so Peter got on the air immediately with it. There have been no failures or anomalies. Without an accurate wattmeter, we are guessing the rig is making a 200 to 250 watt carrier that can be modulated 100% positive and negative. The modulation is clean and linear, with no audio restrictions.

I set Peter up with my Marshall V63 condenser mic running into a Symetrix 421M mic amp/leveler/limiter that has a 6kc second order low pass filter, then into an old BSR EQ3000 graphic equalizer that has small average weighed multi-band "spectrum" metering. The EQ is set to attenuate bass and accentuate midrange and highs. The output of the EQ feeds an Aphex Dominator 2 model 720 three band limiter. The whole chain cost about $200.

We had some hum due to either a lack of grounding or proximity of the EQ to the power transformer of the mic amp or limiter. There was also a very slight amount of RF in the unit. I relocated the EQ to below the transmitter, and added 16 gauge grounding wire from the transmitter chassis to the rack frame, nearby service entrance and the EQ. There was already a ground line to the cold water pipe connecting to the rack.

To limit internal relay contact wear, I added a 12v relay and power supply from the transmitter transmit relay normally open contacts for isolation to feed the R390A receiver break-in contacts for receiver muting. For some reason, the R390A stopped muting from this 6V line the next day even though the R390A's internal relay still activated. For higher fidelity audio I moved Peter's external amp from the line out of the R390A to the diode detector output, but used a 0.1uf cap in series with a 470k resistor to isolate the high impedance diode output from the external amplifier. I then used the second set of contacts of my external relay to short the external audio amplifier's input when in transmit mode to correct for the R390A muting failure.

With the help of folks such as W1VTP, WA1QIX, W1LLY, WA1HLR and others, we spent a few hours tuning the audio processing and EQ for a decently crisp sound. Recordings show a clear and clean signal, but as our processing is not the latest digital Omnia or Optimod, Peter is not the loudest and is a little wide-not from transmitter distortion, but rather the aggressive presence boost of the chain. The Super Senior can take all we feed it until we try to increase the carrier to somewhere around 300 watts (??) where the positive RF peaks run out of headroom as seen on a scope from an external output RF sample. We are now running the transmitter at around 200 watts and the modulation is unrestricted. Peter purchased the optional D104 mic preamp/compressor board and we should be able to test it on a D104 that Roger K1MBX donated within a week or so. Then we will determine if the D104 works better than the outboard processing for his voice.

Attached is a photo and sound clip as recorded from a Yaesu FRG 7700 at my QTH in Natick, MA about a mile away. The receiver was set to 12kc IF passband. This recording was made before the improved grounding and relocation of the EQ.

We will tweak the audio more as needed. Peter has been having good fun running the new transmitter. This Super Senior is bare-bones simple, but has been reliable for the short time Peter has had it. Two key items we have learned is that the modulation amplitude as well as SWR must be controlled so that the transmitter protection circuit does not trip. There are three fans on the front that move some air and are a bit noisy.

Here is a link to Bruce's web site for further information on the Super Senior transmitter.

http://k7dyy.com

73,
Dan
W1DAN



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« Reply #1 on: March 04, 2013, 12:19:53 AM »

I have one of those ADC EQs and love it! Lost the mike somewhere.. no more Acousta-Voicing for me..

I'd heard that the Super Senior had been improved /new design but had not seen one, just heard it talked up on the air by a happy customer.
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« Reply #2 on: March 04, 2013, 04:27:30 AM »

You know you're almost 'there' when the only thing he could criticize was his own voice !
 
Very good recording and you've gotten it dialed in well.

Can't wait to work ZZZ Radio.
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« Reply #3 on: March 04, 2013, 06:28:10 AM »

I do not know how Pete's voice sounds in person, but the recording was easy to listen type audio. Might need a little less 5kc audio.....mid-hi's..Make the smile a little crooked with a little more low end.....If Pete's voice is being reproduced accurately with the present settings; then the TX is ready to go. Just seems a little thin sounding now. Sounds like very nice D-104 audio.
Fred
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« Reply #4 on: March 04, 2013, 09:51:47 AM »

Dan,
The K7DYY sounded very good and it was good working you and Pete yesterday with it. 

The EQ sounded very good when you were on the mic. 

With a lot of the transmitters today having such wide frequency response curves, its important based on ones voice to get the tone balance correct.  I find lots  of stations have way to much low end response and it makes copy less than pleasant especially when conditions are less than perfect.   Those with "softer voices" really get tough to copy with such a heavy low end.

I have noticed also that the K7DYY transmitter don't take up a large portion of the band.  Did you run a frequency response test on the transmitter Dan? 

Joe, GMS
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« Reply #5 on: March 04, 2013, 10:26:24 AM »

Joe -- I sent you an email, it's responsive.

Was corresponding with Bruce a while ago.
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« Reply #6 on: March 04, 2013, 10:52:13 AM »

Hi Dan,

     I heard you and Peter on yesterday. Great to hear a strong quality signal from the ZZZ place.

Thanks for your work. Same to Steve and anyone else who put time in over there.

Dave
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« Reply #7 on: March 04, 2013, 12:53:59 PM »

First congratulations on the new rig.

Now a few ideas:

I'd run it off an isolation transformer.  As I understand it, the power supply directly rectifies line v. to get a high positive v. for the FETs.  I'd be more comfortable with the box running off a 1:1 transformer secondary.

Get an audio sig. gen. and put all the processing gear on bypass and sweep the rig.  You need a good DL; not a "cantenna" but buy or borrow a 1 or 2 KW dry load--four 200 w. carborundum resistors with a fan on them or a Bird dummy load.  Find out what it passes to RF from 0 to at least 10,000 cycles.  Sweep it up to the point you no longer see any audio on the carrier.  Note when the modulation drops below 100% on low and high ends to get an idea of the frequency response.

Repeat with the audio rack engaged.  

That rig should be able to run 300 w. @ 100% up and down.

My guess is the audio driving it is asymmetrical.   Try to work up a trapezoid on the scope.   Center dead carrier and note at full voice modulation the extent to the left and right your pos. and neg. peaks travel.  Pos. is the open end of the trap.; neg. is the pointy end.  You'll probably see the positive extending out more divisions than the neg.   If you drive the rig with a sine wave from a signal gen. and the audio processing gear in proof mode you should be able to get the carrier up to 300 w. and still tx a nice sinusoidal envelope.

Why is the eq. boost maxed out on 8 and 16 K?    I'd have  those channels at maximum attenuation  and 4 K about half down from where 2 K is.  Lose the boost on the low frequencies.  

Unlike many older unmodified ham tube rigs, a solid state rig like that can be driven with compressed peak limited audio to achieve a higher average and level of density in the mid-range that will stand out and survive one or two skywave hops.   I advise the owner invest in an oscillocope if he doesn't have one already, an audio signal generator and seek out a used CRL PMC 300, 400 or 450, set it up for near symmetrical audio, drive it to 6 dB or more gain reduction with a multi-band compressor to take advantage of that rig's ability to stand out and be LOUD.   Roll off the low stuff at 100 cps unless you only want to work guys 100 miles away.    Never run it with a condenser mic.  A rig like that will nicely tx every little saliva drip, breath blast, wheezing nostril noise, spittle, and denture suck a sensitive mic will pick up.   Not to mention any motors or big fans in the shack.  Get a good dynamic with a pop sock. 
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« Reply #8 on: March 04, 2013, 04:05:36 PM »

Dan I dug up some correspondence with Bruce that I had a couple years ago. 

I presume that the performance figures he cited for the "Senior" have carried through and perhaps been improved upon in the "Super Senior."

Here's hoping your positive experience setting Peter up and the results you observed that he now is obtaining will make their way back to Bruce.  I found him easy going, receptive, and quite keen to learn what his customers think of the product.

I recommend a version of your posting (if not the URL) be emailed to him with any additional preamble you might have in mind.

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« Reply #9 on: March 04, 2013, 04:19:59 PM »

Very crisp and transparent sounding audio.   I can hear the subtle smacks of the lips - a good test of the highs and quiet room.  Slight 60 Hz hum - I didn't hear 60 Hz on the second station...

Once the hum is fixed, slide the 65 Hz and 125 HZ up a little.

Good job.

T
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« Reply #10 on: March 04, 2013, 08:25:26 PM »

Good eye Rob
WOW...why didn't I see the EQ. Splains everythng.
I'll still stick to my first post of making that smiley face slightly lopsided and bring the low end up to almost flat and drop the last slider on the EQ all the way and the one next to it down to the flat setting.

If you are at the extremes of EQ to get good audio with Bruce's TX. then you need a better audio match. I ran across the same thing with my Class D  Jr. 80M band. His TX audio input is sensitive to the proper impedance. A Bogen WMT-1 saved the day for me. Looking at it now tells me that my Class D was high impedance. I was feeding mine from my station audio chain using 600 ohms balanced.
I had lopsided extreme EQ settings for reasonable audio. Once I got the proper impedance match, there was almost no need for EQ. I'm using a Marshall condenser mic and the Symetrix 528E. EQ cliked off. Compressor only. Plenty of modulation and nice audio. 130W outpoot.

Check with Bruce on the isolation transformer for your TX. My Class D needs one. Already blew out something by connecting something to the PTT. $80 repair.
The super senior would be a dream TX for me.
Fred
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« Reply #11 on: March 04, 2013, 11:06:30 PM »

Hi all!

Thanks for your replies and ideas. Here is further information.

I spent another few hours at Peter's today, and we improved his audio. To get a clear picture of what was happening. I brought over my ďreferenceĒ Yaesu FRG-7700 receiver and Sony MDR-V6 headphones. This RX has 12kc IF with a clean detector and I can clearly hear how a transmitter is sounding. As a bonus, when listening on FM, I hear when a signal is being over-modulated by the popping of the discriminator. I had not mentioned yesterday that Peter has a bench oscilloscope, and that I loaned him my coaxial RF scope tap, which is connected at the transmitter output. This is where we are seeing the effects of flat-topping the audio and the over-modulation of limited peaks.

As things did not sound as good as it could, I used his scope and found we were sending too much audio from the Symetrix mic amp/leveler and we were clipping the EQ input. Also with Peterís voice, the mic was out of phase. To provide for some positive peaks and to make a firmer limit point for the negative peaks, I added a rare CRL PMC 300 clipper (this is not the PMC 300a limiter, but a very early unit that does clipping only). We now have good positive peaks and the negative peaks just touch the baseline. I got a mod monitor report from Steve WA1QIX to confirm this.

I have not swept the transmitter or air-chain, as I do not hear any anomalies audio-wise. I have the gear, but will not bother. The transmitter has no frequency shaping circuitry, nor any audio transformers. The input is 600 ohms resistive and unbalanced. This is confirmed by looking at the schematics and my passing square waves during extreme clipping tests. I run +4dbu unbalanced to the transmitter input connector where I have a variable resistive attenuator to set final modulation level. Today, we did bring up the 31, 63, 125 and 200hz LF EQ to -5db, but am VERY sensitive to not having too much bass that reduces intelligibility. The extreme HF boost is to correct for an average receiverís roll-off as well as to compensate for Peterís lower than usual sibilance and fricatives. I tuned the EQ by ear and listening off-air and feel that any HF attenuation from what I have will make Peterís voice muddy and less intelligible. If this were my setup, I would need less HF boost, because my voice is brighter. This EQ setting sounds good with Peterís voice using the condenser mic, as confirmed by four stations today as well as my listening to him off-air.

As stated in my initial post, remember that we have a second-order 6kc LPF at the mic processor. This helps control bandwidth, but not as much as I would like. Also remember that the Dominator 2 is a three-band limiter. It also has a single-band final limiter and diode clipper. This is where we are gaining density. Yeah, we need a wind filter, but the audio is clean, has power and is balanced at the receiver. With the condenser mic 6 inches directly in front of the fans, the fan noise is not objectionable (Tom-the hum is solved-had to re-locate the EQ and ground it as stated in my first post-still a very slight amount of RF in it, but you cannot hear it in the audio. Filtering will be done later). No need for further processing, unless Peter decides to work DX at night. We tried an Electro-voice RE-50 and it was too thin.

As you look at the K7DYY documentation, you will see that Bruce is a minimalist. The power supply is a direct line switcher that is modulated. It works very well and has power. My thought is that if something dies in the power supply or RF amp, we could see fireworks, but everything is well grounded so the external gear should be safe. An added isolation transformer would need to be pretty beefy to handle the power, and I feel is not needed here. Yes I did read about past class-D transmitter failures, but feel this design is more mature. It has worked flawlessly with no trip-outs or failures.

Finally, we need to measure power with a Bird wattmeter or other known accurate meter. Right now we only have a Radio Shack SWR bridge, and Peter really wants to know how much power he is indeed making (me I do not care +/- an S-unit). Rich KA1ETP offered to bring his Bird over sometime. At this time, I am guessing (yes only guessing) we may be making around 200 watts fully modulated, but I do not really know. When we bring the RF power up, the modulation runs out of steam and flat-tops, so I set it so we are not restricted peak amplitude wise. Bruce stated he tests his transmitters with 100% sine wave modulation at full power. Either way, the transmitter sounds great and is clean and efficient.

Others helped me with on-air tests and recordings of the new setup, which are very valuable. In general I have received positive and valuable assistance from many hams. I want to get my PMC300 back sometime, so may try to snag a PMC300A or make a simple negative diode clipper for Peter.

Peter is very happy and having fun. To me this is success in itself.

Thanks for your support and ideas.

73!
Dan
W1DAN
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« Reply #12 on: March 05, 2013, 07:06:59 AM »



Dan,

   Thanks for sharing this experience with us. I found this thread and the results most interesting..especially when it would take a rack of decks similar to a Globe King 500 to make high level AM at this power level, but no disrespect to WRL or Leo Myerson; the stock GK 500 never sounded this good.  Smiley

   One thing you said made an impression upon me, "As you look at the K7DYY documentation, you will see that Bruce is a minimalist. The power supply is a direct line switcher that is modulated. It works very well and has power."

   So in that spirit, I wonder how a "Super Senior" would sound, and perform with Bruce's own audio processor mated with a D-104 microphone?

Jim
WD5JKO

 


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« Reply #13 on: March 05, 2013, 08:19:44 AM »

Audio sounded very nice and assume the hum is pretty much gone now but if you have to dial it back to 200 watts, why your back to the DYY Junior!
..and at what was a lot fewer sheckles. Huh
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« Reply #14 on: March 05, 2013, 08:28:51 AM »

Hi Jim:

Good question!

Peter purchased the D104 mic amp/compressor board when he bought the transmitter. I installed it in a D104 that Roger K1MBX donated, but it did not work. I have to check my wiring as I bet I missed something.

I told Peter there is a 50/50 chance that a D104 may sound better than the air chain. I often hear folks who have a good voice for a D104 and have the mic mated well with their transmitter, and listening to them through audio processing results in their not sounding as loud.

As for power level, we will find out where we really are when we can make an accurate RMS power measurement.

Thanks,
Dan
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« Reply #15 on: March 05, 2013, 08:33:36 AM »

Hi all!
Thanks for your replies and ideas. Here is further information.
I spent another few hours at Peter's today, and we improved his audio. To get a clear picture of what was happening. I brought over my ďreferenceĒ Yaesu FRG-7700 receiver and Sony MDR-V6 headphones. This RX has 12kc IF with a clean detector and I can clearly hear how a transmitter is sounding. As a bonus, when listening on FM, I hear when a signal is being over-modulated by the popping of the discriminator. I had not mentioned yesterday that Peter has a bench oscilloscope, and that I loaned him my coaxial RF scope tap, which is connected at the transmitter output. This is where we are seeing the effects of flat-topping the audio and the over-modulation of limited peaks.
As things did not sound as good as it could, I used his scope and found we were sending too much audio from the Symetrix mic amp/leveler and we were clipping the EQ input. Also with Peterís voice, the mic was out of phase. To provide for some positive peaks and to make a firmer limit point for the negative peaks, I added a rare CRL PMC 300 clipper (this is not the PMC 300a limiter, but a very early unit that does clipping only). We now have good positive peaks and the negative peaks just touch the baseline. I got a mod monitor report from Steve WA1QIX to confirm this.
I have not swept the transmitter or air-chain, as I do not hear any anomalies audio-wise. I have the gear, but will not bother. The transmitter has no frequency shaping circuitry, nor any audio transformers. The input is 600 ohms resistive and unbalanced. This is confirmed by looking at the schematics and my passing square waves during extreme clipping tests. I run +4dbu unbalanced to the transmitter input connector where I have a variable resistive attenuator to set final modulation level. Today, we did bring up the 31, 63, 125 and 200hz LF EQ to -5db, but am VERY sensitive to not having too much bass that reduces intelligibility. The extreme HF boost is to correct for an average receiverís roll-off as well as to compensate for Peterís lower than usual sibilance and fricatives. I tuned the EQ by ear and listening off-air and feel that any HF attenuation from what I have will make Peterís voice muddy and less intelligible. If this were my setup, I would need less HF boost, because my voice is brighter. This EQ setting sounds good with Peterís voice using the condenser mic, as confirmed by four stations today as well as my listening to him off-air.
As stated in my initial post, remember that we have a second-order 6kc LPF at the mic processor. This helps control bandwidth, but not as much as I would like. Also remember that the Dominator 2 is a three-band limiter. It also has a single-band final limiter and diode clipper. This is where we are gaining density. Yeah, we need a wind filter, but the audio is clean, has power and is balanced at the receiver. With the condenser mic 6 inches directly in front of the fans, the fan noise is not objectionable (Tom-the hum is solved-had to re-locate the EQ and ground it as stated in my first post-still a very slight amount of RF in it, but you cannot hear it in the audio. Filtering will be done later). No need for further processing, unless Peter decides to work DX at night. We tried an Electro-voice RE-50 and it was too thin.
As you look at the K7DYY documentation, you will see that Bruce is a minimalist. The power supply is a direct line switcher that is modulated. It works very well and has power. My thought is that if something dies in the power supply or RF amp, we could see fireworks, but everything is well grounded so the external gear should be safe. An added isolation transformer would need to be pretty beefy to handle the power, and I feel is not needed here. Yes I did read about past class-D transmitter failures, but feel this design is more mature. It has worked flawlessly with no trip-outs or failures.
Finally, we need to measure power with a Bird wattmeter or other known accurate meter. Right now we only have a Radio Shack SWR bridge, and Peter really wants to know how much power he is indeed making (me I do not care +/- an S-unit). Rich KA1ETP offered to bring his Bird over sometime. At this time, I am guessing (yes only guessing) we may be making around 200 watts fully modulated, but I do not really know. When we bring the RF power up, the modulation runs out of steam and flat-tops, so I set it so we are not restricted peak amplitude wise. Bruce stated he tests his transmitters with 100% sine wave modulation at full power. Either way, the transmitter sounds great and is clean and efficient.
Others helped me with on-air tests and recordings of the new setup, which are very valuable. In general I have received positive and valuable assistance from many hams. I want to get my PMC300 back sometime, so may try to snag a PMC300A or make a simple negative diode clipper for Peter.
Peter is very happy and having fun. To me this is success in itself.
Thanks for your support and ideas.
73!
Dan
W1DAN

Dan,

Fantastic description of the thought process and actual testing.  I always agree about equalizing it for the typical 6KHz receiver which most people use.   On my own station, I set it up in a very similar way.  After all, isn't the goal to sound good on most peoples receivers?  Some do have capabilities to go wider bandwidths on the receive end but most op's do hang around the 6KHz when it comes to receiver selectivity. Its for that same reason that I choose not to run extended positive peak modulation since most people are just running the standard diode  detector.  I have never felt this method was a deterrent when running my station.  

Peter is lucky to have a knowledgeable audio mentor like yourself to help him out.

73,
Joe, GMS  


So in that spirit, I wonder how a "Super Senior" would sound, and perform with Bruce's own audio processor mated with a D-104 microphone?
Jim
WD5JKO


Jim,

Ed, KA3PTX uses that exact set-up with his Super Senior and I just worked him the other day with it.  It sounded very good for the simplicity of the set-up.  The quality was very good and sounded nicely balanced.  

I do think with external audio chain it could be raised up a notch but again it did sound very good with just that simple set-up.

Joe, GMS  
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« Reply #16 on: March 05, 2013, 08:47:38 AM »

There's no such thing as RMS power.  If you have a 3 A thermocouple RF current meter and a 50 ohm load, put the meter in series with the center of the coax feed to the load with the shield bypassed around it.  at 300 w. you should see about 2.4 A on the meter.  Only run dead carrier--don't modulate it or you'll blow the meter.

<<There was already a ground line to the cold water pipe connecting to the rack.>>

I forgot to mention this before:  Don't rely on a cold water pipe ground.  That is an old practice that is no longer prudent.  The reason is that you can have out of sight delectric junctions in the plumbing or the exterior service below grade may have been replaced with non-conductive pipe, or some other fault.   He should have a few copper clad rods driven in right outside of the shack with a copper strap about 3 inches wide brought in.  If possible make it near the electric service entrance and tie it all together there.
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« Reply #17 on: March 05, 2013, 09:54:21 AM »

<<There was already a ground line to the cold water pipe connecting to the rack.>>

I forgot to mention this before:  Don't rely on a cold water pipe ground.  That is an old practice that is no longer prudent.  The reason is that you can have out of sight delectric junctions in the plumbing or the exterior service below grade may have been replaced with non-conductive pipe, or some other fault.   He should have a few copper clad rods driven in right outside of the shack with a copper strap about 3 inches wide brought in.  If possible make it near the electric service entrance and tie it all together there.

That's probably not what's causing it, read the grounding information again:

We had some hum due to either a lack of grounding or proximity of the EQ to the power transformer of the mic amp or limiter. There was also a very slight amount of RF in the unit. I relocated the EQ to below the transmitter, and added 16 gauge grounding wire from the transmitter chassis to the rack frame, nearby service entrance and the EQ. There was already a ground line to the cold water pipe connecting to the rack.

It might not be that the cold water pipe ground isn't really grounded, but that having that on there is now causing a ground loop between the service entrance ground and the water pipe ground.
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« Reply #18 on: March 05, 2013, 10:15:35 AM »

The bandwidth for a receiver going beyond 6kc is a catch for interference and nearby SSB.. We are trying to fill the space with nice audio.
And there shouldn't be too much concern for the loudness. Just nice to fill the spectrum with nice audio.
I don't want to be real critical, but the EQ is a consumer device and will hiccup in the presence of RF. Unbalanced hi impedance in/outs. Grounding aint' gonna help.
I have had zero problems here with QRO on any band with the Symetrix and the DBX EQ. All balanced audio.
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« Reply #19 on: March 05, 2013, 10:22:36 AM »

I am a bit puzzled by the spec of 1500 watts PEP on a 300 watt carrier, but no more than 100% positive modulation. Obviously I am missing something.

Looking at Peter's modulation on the scope that is hooked to the IF of the R-388 I saw not much positive modulation, and some dives to the baseline.

I downloaded the schematics on the site, and did not have a chance to look closely at them... it might be possible to make a mod to the PWM circuit along the lines of what QIX does in his class E PWM circuit so that one can go positive and not clip the baseline. That would be sweet.

Of course I am sleep deprived at the moment and may be babbling (again, still) incoherently...

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« Reply #20 on: March 05, 2013, 11:39:32 AM »

I have been using a Super Senior transmitter for just over a year and am delighted with it. It is a great design and implementation with only a few minor quirks.

Up until recently I used it with Bruce's processor board in the base of a D-104 and received many reports of outstanding audio.  Recently, I am experimenting with an external audio chain similar to the one under discussion here.

Today, I set up a Yahoo Group called "IndexLabsAMXmtrs" so that we could share information and experiences with our Super Senior transmtitters.  Everyone that is interested is encouraged to particpate.

I did contact Bruce, K7DYY, and he encouraged me to set up this group and will participate as his time allows. However, it is primarily meant to be a user-to-user discussion group.

Craig
W6DRZ
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W1DAN
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« Reply #21 on: March 05, 2013, 01:41:31 PM »

Hi Rob:

In performing an accurate power measurement, we expect to use a Bird 43 wattmeter into a load of known resistance. In our case it will probably be a Cantenna. I can also make a resistive pad and scope the p-p carrier voltage as a secondary measurement into the known resistance. To clarify, when I meant RMS power, I was thinking of average power running an un-modulated carrier into the load and see where the Bird measures after it stabilizes. I do not believe in peak power while screaming into the mic as the peaks can be short and of little average area and thus power. There is such a thing as RMS power (think audio amplifiers), but I will not enter into an argument about it as this is not important to me. If you wish to loan us a thermocouple with calibrated meter, or calorimiter and load, we would be thankful and share our test methods and results.

Finally, as it is winter here and the ground is frozen, we will not be adding any ground rods soon. Peter's house is old, and we feel pretty confident that the piping leaving the house is not plastic. This single water-pipe ground was questionable for me, so I added a line to the electrical service entrance ground and bonded things together. Yeah, I know it is not optimum and could be a ground loop (especially at ten or 15 meters as my wire is short, and even through the rack screws and power cord grounds), but it will do and we now have better grounding with firm connections to the gear of interest, all tied together. It reduced the level of RFI into the system, and all other gear is stable. Also, in my 30+ years as a radio amateur, I have never seen that just adding a ground rod fully clears up all RFI. For me, RF is eliminated by moving the antenna away from the shack, having low SWR, and tying all gear together to a grond. Then I attack with capacitors and chokes as needed inside the affected piece of equipment. The EQ needs it, and we will get to it.

As the MOP-man stated here, the EQ is a consumer item. Unbalanced and -10dbu, and this unit obviously has no RF filtering (I did not expect it to), and I do experience RF from the audio input. Before I ran a ground line to the case of the EQ, we had too much RFI making the chain unusable. I agree that a pro EQ with balanced lines would be better, but this EQ cost $10.00 at a yard sale and Peter likes the spectrum display. There is a nice singe channel dbx 131S graphic EQ that sells for about $150.00 that looks pretty good that was considered. Peter did not want to buy it yet as he has already shelled out lotsa money to get here. If he had money, I'd have him just buy a digital Optimod or Omnia and call it a day. To me the fun is making the motley crew of hand-me down gfear sound good. FWIW, at my home station I run all pro-gear. I have star-quad mic cable and made one for Peter. I even had to extensively filter my 'pro" ATI mic amp. I have no RFI.

Mop-Man: I do not want Peter to be "the loudest", just comfortably listenable and clean. The Dominator has limits to how dense it can be, but it is a very clean limiter. Heck, Peter sounds better and louder than my station! My FroG 7700's 12kc filter allows me to hear what a station is doing, and I do not normally listen this wide. Most people will be listening with narrower receivers, and so the audio must remain balanced for these folks. I believe we have achieved this. I only wish our transmit audio LPF was steeper at 6kc to be a good neighbor.

Bear: Since that recording was posted, we obtained better modulation swing due to solving the issues stated earlier. The K7DYY input feeds the PDM chip with no processing, and so all control and filtering (especially aliasing) must be done external to the transmitter. You'll hear Peter again soon on the air, so give a fresh listen. Bruce told me he measures his PEP power with a sinewave (not sure how or with what). As this is done with tone, it will be symmetrical.

Craig: Thanks for creating the Yahoo group. I will tell Peter about it. I bet it will be a fun area. Glad you are enjoying your transmitter!

Next will be to get the D104 working.....

Have a great day y'all!

73,
Dan
 

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flintstone mop
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« Reply #22 on: March 05, 2013, 07:04:58 PM »

I am a bit puzzled by the spec of 1500 watts PEP on a 300 watt carrier, but no more than 100% positive modulation. Obviously I am missing something.

Looking at Peter's modulation on the scope that is hooked to the IF of the R-388 I saw not much positive modulation, and some dives to the baseline.

I downloaded the schematics on the site, and did not have a chance to look closely at them... it might be possible to make a mod to the PWM circuit along the lines of what QIX does in his class E PWM circuit so that one can go positive and not clip the baseline. That would be sweet.

Of course I am sleep deprived at the moment and may be babbling (again, still) incoherently...

                    _-_-

multiply the carrier times 4. That is PEP.
So the 300 watt carrier is actually 1200 Watts PEP..We are allowed 1500W PEP for all modes.
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Fred KC4MOP
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Brrrr- it's cold in the shack! Fire up the BIG RIG


WWW
« Reply #23 on: March 05, 2013, 09:50:29 PM »

the K7DYY site claims 1500watts on a carrier of 300 watts with 100% max modulation.

Could be a typo.

Cheesy

                 _-_-bear
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_-_- bear WB2GCR                   http://www.bearlabs.com
ke7trp
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« Reply #24 on: March 05, 2013, 10:53:07 PM »

The Bird43P reads at 2.828 times.  Its in the bird literature.  Calibrate your scope to 2 lines, adjust audio to 100% and read carrier and bird pep meter.  It will be just under 3 times. So trying to get 4 times the carrier will be over mod on that meter. They will show an imediate increase in PEP when the mic phase is flipped while speaking so maybe this guy has the mic backwards to his voice.

The Super Senior transmitter is really neat.  They sound fantastic with the D104 board installed.  Actualy, Some of the best audio I have heard.  Very CLEAR, CLEAN and LOUD.  Not over boosted bass and cranked highs.  Tons of clear talk power.  There are a half dozen or more running around this side of the coast.   Its really neat when one of them comes on 40 db over so clear and loud you are blown of of the chair and then a guy with a 900lb BC transmitter keys up next with the lows boosted and no talk power.. Smiley

I understand that they run great at 250 to 300 carrier.  325 if the SWR is dead flat, 375 and you might get some trips of the protection sytem. Most end up setting around 300 and leave it be.   

If the transmitter had 40 meters in it, I would get one in a second.  Its really incredible. 2 rack units, a single 110 volt line cord, full legal limit AM and super audio. He did a hell of a job on it. 
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