The AM Forum

Looks like k7dyy has a new transmitter for sale soon....
300 watt carrier.
$680.


http://k7dyy.com/index.htm

Wow, impressive small size for 1/3 kW carrier. Now we're talkin'. Oops, thats an ARRL saying.

I had a whole lot of fun building and using Bruce's smaller creation which he now calls the DYY jr.   The Junior is a great little transmitter 200 watts, two pounds (Bruce says 150, but I turn mine up to 11).   The external T/R  of the junior is inconvenient and 150  watts isn't enough for my tastes.  Three hundred is more like it.

This design is a descendant of the earlier design which proved to be quite robust.   After correcting my stupid construction mistakes, nothing blew.   However, if you plan to build this baby, plan on using an isolation transformer for bring-up.   Don't go poking a scope probe in there without isolation.   There is no HV transformer.   

I think I'll buy the boards since all my horsing around building the Junior as he was designing it and fooling around with Class E has left me with most of the parts.   Besides, I'll have to make mine look more boat anchor like -- black wrinkle, and some meters for something.

Jon

You must super sharp eyesight!! When I bought the kit I had to "upgrade" and send it back for Bruce to build. I couldn't see half of the components. Soooo he's up to 300 watts now??? You are pushing 200 watts out? Modulation ok and no overheating??

The audio response is ok for a D104 input. I'm inputting the audio from my station and you have to watch the high end or it will splatter all over the place. The "junior" has a strange response curve. Definitely not flat. I have my mic processor set at very peculiar settings for "normal" voice response. I think by typing this that I have discovered the reason for the peculiar setting for the EQ. I'll recheck the setup of the Transmitter and make sure it is 600 ohms and not 5 billion ohms for the D104.
Fred

That is pretty cool.
I've heard Fred's "junior" model and it sounded good.

http://wa3vjb.amham.com/sound/KC4MOP.mp3 (http://wa3vjb.amham.com/sound/KC4MOP.mp3)

I had done very little surface mount work before the various DYY transmitters.   I got comfortable with it after awhile -- lots of light, magnifiers, and tweezers.  I did it the hard way, though.   Bruce started with a class E kit which I built.  It worked great.   Then he hacked on that to make the class D.   I hacked in tandem and built my own RF board from his design.   Then I got boards from Bruce and threw away the mess that this thing had become (but it worked) and rebuilt it all over again on his .9 version boards.  All of them worked. 

Yeah.  200 watts.   He called the thing a 200 watt transmitter when he first designed it.   It does fine at 200 watts, 100% modulation.   At 150 watts you can push 125% or so, I'm told.   I don't do that. 

You can hear one almost daily, Larry, W8ER, has been field testing one and not babying it either, 300-310 watt carrier, Modulating about 1200 watts, and the thing sounds amazing! 5 Amps/110 volts! I am contemplating one for a back-up in case my main AM rig goes down...

I havn't heard a guy yet that hasn't gone out of his way to compliment Larry's audio, the thing is fantastic.

I have been monitoring Bruce using the "300 watt" rig....He is testing it at 350 watt carrier output and it sounds very good and very strong...  I would really like to have one  but I don't think I would be able to build it with my size 16 hands... those dead bug parts are just too small...those with average size hands and eyesight should have no problems...one of the best sounding rigs around!

I've been debating about getting the Junior (more in my price range) for some time, for some 160m capability.  Also, as you know, I'm hesitant to run much more power than the Junior puts out, where I live.  Of course considering my funds - it would be when I get the money.   OK, now a dumb question - like the Class E rigs, I assume that it has no oscillator/exciter section or a modulator (in other words it's not a really transmitter per se, but a final amplifier section)?  So, in other words, I'd have to come up with a modulator (or as I've been told, a cheap audio amplifier would probably do the trick), and an exciter?

73,
Ellen - AF9J

You don't have to worry about building it......

They are NOT kits..... only bare boards with NO parts, or a assemlbed/tested unit..

And noo more K7JYY  "JR".... he;s not making them anymore.....

Ellen,
         IIRC, Randy N3LRX brought one of those by here one night, and I believe the one he had was a complete unit with switching poewr supply, modulator and all in one little box.
Just add crapstal, mike and antenner. It was a really small compact unit IIRC, just not my cup of tea.
                                                                              The Slab Bacon

Ellen,
Looks like the new SR model has 6 selectable xtal sockets....

So, yes, it is "self contained" transmitter.......

(Don't know why he wouldn't need FCC type acceptance...... but that's not my concern.)

Cool!! Thanks for the info guys!  I've always been intrigued by the Class D & E stuff.  I know K7JYY sells them built complete (and in some cases, sells the boards).  Still, a kit would be fun to put together (I always enjoyed building my QRP kit rigs).  No more Junior!!?   :'(

<Sigh!>
Ellen - AF9J

Randy bought the "kit" version. IIRC most of the low level stuff was all surface mount, well squished together. (This was before my eye overhaul) I dont think at that time I could have seen well enough to build it. I remember that Randy had a pretty tough time with it, and I couldnt see well enough to troubleshoot it at that time.

I do remember that it had just about no tuning adjustments in the RF section, and none at all on the final amplifier board. It was a very small package for the rated 300w carrier outpoot.

But it will never take the place of the glow of some big firebottles behind a peek-a-boo window for me!!

                                                                              the Slab Bacon

I have that particular unit now.......

Randy sent it to me to finish, and test...
He ended up trading it to me for parts to build a QIX class-e....
Haven't heard from him for quite a while....


The "JRs" at first were rated a lot higher.... but then after a bit Bruce k7dyy, lowered the advertised/recommended carrier level.

I like 'em both (hollow state & Class D & E).  The electronics I was taught in college was all solid state.  Tubes - well, that comes from using tube guitar amps, and the fact that all of my rigs until 1993, were either tube or hybrid.  Like I said, both are cool to me.  Tubes look cool when they're doing their thing.  Chronically having a lack of space, also makes compact stuff (like Class D & E) attractive to me.

73,
Ellen - AF9J
Using a notebook computer to type this

its an attractive tx for me, because I cant handle the big stuff anymore.

Hi Guys...I don't often post here but thought I would today..My K7DYY 300 watt
will be here today. Bruce shipped it yesterday...Hope to have it on the air tonight..
Am going to use a K7DYY D104 to start with... Bruce said that it worked great over the weekend... Will let ya all know what happens


Bob W1PE
Mesquite, TX

Why not?

Please let us know how the K7DYY rig works for you. I think many are interested.

Please do.  When I have the cash, I'm think about going the K7DYY Class D, or the Class E route, to get on 160m AM.

73,
Ellen - AF9J

Well folks the K7DYY Sr is on the air. On the MFJ Peak Meter it is running about 320watts Cxr and peaking to 1200 plus watts. I am using the K7DYY D-104 pre amped
mike with it...According to Brian WA5AM I was running neck and neck with an RCA at 350 watts out and the audio sounded better then a lot of guys with full audio chains...
This puppy weighs about 9 Lbs...Good for us Old Guys that can not lift stuff... It has 6 Frqs in it.. Love that Big Red light when you key up... So far worth every penny paid...
Ohh By the way Brian said that it was about 3.5 Kc either side of center and dropped off well.. That is good as well...

That is the first report...

Bob W1PE

I heard Bob this afternoon on the new class D and it sounded really good, however at that time of day, about 4:00 PM, propagation was not that good between us.  Best I could tell, it had a nice roll-off right at 3600 or 3700 cycles each side of center, and audio seemed to be smoooooooth as it gets...

Yeah Bob, why don't you visit here more often man???!!!

I'll try to catch you tonight, just give me a one ringer, or send an email.

Nice! A Nine Pound Hammer. I love it.

...how is this thing programmed for it's freqs?....it wud appear it cant qsy down,or up 5kc, unless it is programmed?...channelized operation seems weird....tim...sk...

It is crystal oscillator (dip) controlled.......
You order the frequencies you want put in it.
Anywhere in the band you want.......

Greetings and salutations...

I have purchased a 75m version of the K7DYY SR transmitter. I must say that I absolutely
love it! When I get on with that transmitter, I am heard, and make lots of contacts. It
plays exactly as advertised with a conservative 300w of carrier. I am told that it will do
considerably more. I got all six channels programmed in 5 khz increments, starting at 3870.

I also purchased one of Bruce's audio processor boards, which is a must with the 'DYY. I
installed it in the base of my D-104. I have received glowing audio reports and nothing but good so far. It is definitely a winner and I highly recommend it. While running 300w of carrier on a typical long keydown AM contact, the DYY SR cabinet is barely warm to the touch.  I have paired my 75m DYY SR with a Drake R4 receiver. The size of the transmitter is less than 1/2 of the size of the R4. This makes for an excellent station that can fit into a very small space.

I like the 75m model so much that I plan to purchase the 160m model in the near future, when
my financial situation permits.

I look forward to chatting with you on 75m AM with my new powerhouse.

Best regards,

Gary E. Kohtala - K7EK

Gary if there's any way someone you're in QSO with can roll a sound file of how they are receiving you, I would really enjoy hearing the new transmitter.

I also wonder if you've collected any thoughts about the characteristics of the audio processing board you mentioned. 

I am very curious whether the attack/release constants are sort of like the kind on your basic communications transceiver, or whether they allow some adjustments for peak limiting and a variable amount of slower acting amplitude compression.

I have two of the K7DYY Mic Pre amps one on the D104 and one on a 10DA. Only adjustment I have found is the gain control. There is no documentation on it at all. That is the one thing I as well would like to see.

I sure do wish that my Sr had worked out. When it was on the air it was great but it would not stay stable so I am back to the old Globe King  LOL

Bob W1PE

...i shud have mine, next week. i chose 160.
  what is this i've heard about using an isolation transformer?...is there some problem i shud be aware of, before i put it on the air?...tim..sk..

Hello All,
I own the K7DYY JR. which was Class D and capable of operating the entire 80M band without tuning. It's being repaired because of the shortcut of not using a transformer for isolation.........my bad and I think Bruce's bad, but he wants $80 to fix. It will have to sit until next month.

My question to the Forum about the K7DYY transmitters is about audio inpoot. I'm feeding mine with 600 ohms unbalanced audio and my EQ settings have to tweeked waaay out from their "normal" settings for the Kenwood/Titan station. How are your Class D or E transmitters performing using a typical Ham Radio station setup/audio chain??? OR no audio chain and or EQ. I'm wondering if my audio impedance is way off making me have to boost-tweek-EQ so much??? Anyone notice the high end restriction?? Too much sibilance and the transmitter goes to pieces!!!
Thanks
Fred

A comment on the audio processor for the D-104.
There are no adjustments for attack/release and the design seems to be for very aggressive processing. In between words I hear my background room noise popping up in the TX audio. I set the mic aside for bad conditions.
I increased power of my "JR" to 200 watts and the modulation went to pot. I reset the power adjust to the 180 Watts approx. and modulation was beautiful. Maybe a weird thing with the Class D design.
When mine returns from repair, it will be nice to be anywhere on 80M and not have to worry about crapstals or tuning. I had good success with the VFO before I zapped the dam thing soldering wires to the PTT plug on the TX, while it was OFF BUT still plugged into the AC mains.

Fred

...maybe i missed it fred, but what vfo were you using,  and how did you wire it in?..tim..sk..

Guys
Check with Bruce about using a VFO. I don't think his new generation of K7DYY Tx's will give you that luxury.
And I think he was modifying the PTT circuit to be self contained and no further dangers of zapping the TX because of the lack of isolation transformer.
Bruce recommended a 500VA transformer for the old JR Class D 180Watt.
For you folks buying the 300Watters you will obviously need a bigger transformer.
"BAD THINGS WILL HAPPEN IF YOU DON'T!!!" Quote directly from Bruce

fred

Howdy,

 Well other than some of these short comings that have little solutions to over come..How does everyone that owns one of these things Like'em...I'd like to know...i'm sure others would too, pleased with service.performance..etc..?...

73.

k7dyy's ccts use either the SSM 2166/2167.  Both chips have a noise gate facility to drop gain below a certain threshold. I was using a different SSM2166 cct here until I went over to using the PC for processing. Changing comp ratio, noise gate point and limiting point  is just a matter of changing resistor values. Check out the data sheets on the Analog devices web site.

http://www.analog.com/en/prod/0,,765_1075_SSM2166,00.html
http://www.analog.com/en/prod/0,,765_1075_SSM2167,00.html

                                             Ian VK3KRI

I found the problem with the quirky weird EQ settings for my "JR".........Bad mismatch from the station audio which is 600 ohms balanced and the inpoot to the "JR". I have many of those BOGEN WMT-1 matching transformers and when I installed it to feed the "JR", it sang it's little heart out with fantastic audio and the EQ is almost flat with a little rise around 4-5khz for listeners using narrow BW receivers.
Now I'm looking for a 500va isolation transformer

Fred

Those of us in the northwest have been listening to Bruce's beta-tested radios for some time.  They sound great.  I'd direct you to W7JHS' website. 
     [url]http://www.w7jhs.com/[url]
where you'll find fotos of Cormack's vast assortment of rigs.  Scroll down to see the DYY junior and senior.  The Senior can be heard afternoons on 3870.

The Senior sounds as good (or better) as any of the other rigs.  Seemed to take just a little on-air adjusting to get the pre-amp set right, but the Senior is a FB AM rig.  Plan to purchase one myself...
 

...got my tx about 10 days ago...just working on getting the audio nice...325 watts carrier on 160. so far, i've received gud reports, on the audio, as well as signal strength received...so far, i'm impressed...tim...sk..

I have purchased one of K7DYY's SR transmitters for 75m, in addition to
his audio processor for a D-104 microphone. I have paired it up with a
Drake R4A receiver.  I must say that I have been extremely pleased with
the quality and performance of the transmitter. It is simply beyond comparison....
When I call, I get answers most of the time. After setting the audio with my
Heath monitor scope, I've been given nothing but superb audio reports. The nice
thing is that this transmitter puts out a very big carrier in a comparatively small
package, and does not even get warm in the process. A typical yay-emm ragchew
session might often entail continuous key down times of 10-15 minutes. With the
'DYY SR,  it just keeps on going and going, never getting warm. I like the 75m
'DYY SR so much that I will soon purchase the 160m model.  I highly recommend
these transmitters. You cannot go wrong. They are worth every penny.
See you on 3870  :).

Best regards,

Gary, K7EK

Ordered K7DYY Sr. PCBs today.  ;-)

Rich