The AM Forum

I have a unique situation in that I am a migraint workerand live in a RV. I have a limit to power outel amps like 15a max. I also have a limited space to set up an AM station. I also do not have the workbench space to build. So knowing this what class D or E transmitter would be best for 200-300w output? What comments about said transmitter?

Well, if you can't build your own transmitter due to lack of bench space, or for some other reason, you can have one built for your.

Contact Bruce, KF1Z at bruce@greenmountainradio.com .  Bruce has built class E transmitters for other folks, and he could probably build one for you.

You will end up with a very high quality transmitter that will be well built, and is actually capable of running the power it clamis to be able to run - with high modulation capability.  It will also be reliable.

The whole transmitter will fit nicely in a table rack or stackable road cases (portable racks) and will not occupy a lot of horizontal space  8)

Regards,

Steve

K7DYY, 300 watt single banders still being made?  I know he discontinued his 'Jr.' but I think he's still making the 300 watt model.

yes, here it is;
http://www.k7dyy.com/ (http://www.k7dyy.com/)

Actually the power limit you have is proportional to the size of the batteries that you haul around and the size of the power inverter(s) that you install...

But beyond that, the K7DYY is likely the smallest, lightest one out there.

One built around Steve's designs is larger, but has some technical advantages.

You'll want one of those "tennis ball launchers" I am sure... they were discussed in a thread on here, do a search - but what did they call them?

But the 300w carrier range should play nicely no matter what... you just need to be able to string up an Ant, maybe you want a deployable pneumatic mast on the RV? 5 sections will get you 50 ft up in the air... not too shabby. Even a crank up tubular done in PVC schedule 80 for the bottom, and maybe aluminum for the last two on top would be light enough and work ok... ur just hanging a wire off it...

            _-_-bear

Ant. is not a problem, I hang up a inverted diapole in the trees. It works well. I have a b5tv on mount from back of the ladder for 20-10m. Tuner a must..

Hi Jerry,

My two cents ...  Have most of the parts here for WA1QIX Steve's transmitter.  I did llook carefully at the K7DYY  rig.   It is my observation that the DYY design pushes the parts too hard.  That is,  the parts do not seem to be up to the stress placed on them.

Several friends who have the DYY design have had to have them repaired several times.

Bruce,   K7DYY will get things just right in time.   His stuff is very clever, compact,   and usually comes assembled.   And a number of folks  have had very good luck with the DYY transmitter,  but  in a transient environment,  where  antennas may be imperfect and variable,   you might be better off with a rugged QIX design.

Here,  have cdonsidered building my QIX desktop AM rig into a recycled  PC case ... little disktop area required etc.   Steve';s design seems to have ruggedness as a design hallmark --  just my opinion.   And  I'm not trying to take pop-shots at DYY Bruce ... he is a very clever engineer.

73  Good Luck and have fun on AM.     Vic

I understand on the k7dyy box there were some good and not so good reports. I understand Fred had to use an isolation transformer and an audio coupling transformer for his audio chain. I'm not sure the set-up, but would be interested in the set-up and the function results.

The minimual margin on the FET's was a concern of mine when reading up on the class D dyy. My issue is I am a contract worker and do not have the space in my trailer to set up and build anything. So avaliability of a built e-class is an issue. Unless I fine one thet has been built and is for sale I don't think the Class E QIX design will make it onto my samll space in the trailer. Thanks for the 2 cents, I wonder if I qualify for a Baiout.

How much space can you spare for a Modulator/power suplly, and a transmitter?



My personal transmitter is 19" wide, 14" deep and 8 1/2" tall,   and the modulator/powersupply is 19" wide 12" deep and 5" tall.


Just built a 2 band (160/75) into 2 seperate 16" x 16" by 6" table-top boxes.
(That's 450watts DC INPUT at carrier)

The modulator (PWM) can't really get much smaller, except by taking the power supply to another box. Still all the same space, but could be arranged differently.

The Transmitter can get smaller by going with a single-band  and using a vac-variable cap for the series tuning C .... ( instead of the HUGE bread-slicers I use.... those are 5" x 5 1/2" x 9")



The only other note on the DYY rig, is it's "channelized"  you get 6 channels, so you can't slide a few kc to get away from noise/qrm etc.
But, it IS tiny!

What is so wrong with a good SSB radio that has AM capability and a solid state linear amp? If you want it hollow-state, you can do a Yaesu early-80's rig and a Heathkit HA-14 linear amp. You could mount them under a cabinet.

Why make the generation a requirement - any way to make AM works.

I have a FT-902dm and Al-811 but the necessary head room is not there. 100w carrier is all it will do without over driving the amp. For the price a clas d or e will out do the transciver and amp.

The below would fit fine... I just do not have time or space to build them.

My personal transmitter is 19" wide, 14" deep and 8 1/2" tall,   and the modulator/powersupply is 19" wide 12" deep and 5" tall.


Just built a 2 band (160/75) into 2 seperate 16" x 16" by 6" table-top boxes.
(That's 450watts DC INPUT at carrier)

at best you will get 3 bands out of a class e final. you can operate one mode.
A good transceiver with a solid state linear will cover 160 through 10 or even 6 meters. It will operate all modes. So it depends on what you want to do.
High efficiency and a couple bands or less efficiency but able to work all bands all modes.
I like both options myself and working on both.

Jerry,

I built up a PDM class E rig with 20 pills a few years back.  Used RS PC boards with point to point wiring. The pre-fab boards available today are MUCH better.

The rig ran FB for about 6 months. Nice sounding too.  After a while it got boring with no glow to view and nothing to fix... :-)   One day I ran the voltage up too high and it caught on fire.

I was probably looking for an excuse for some action. Tore it down and recycled the parts into a tube transmitter. Since then I've built all tube rigs and get plenty of action.  Might build up a SS rig again some day.

Recommendation?  Highly recommended, but keep a big tube rig in the shack too - to mix it up.

I wouldn't hesitate to have Bruce build one up for you.

T

Every now and then I look at my box of 813s and get a similar feeling but also would like to build a QRO solid state linear now that I have all the stuff.
You can't beat class e in the summer and the warmth of a tube in the winter.

...k7dyy transmitter, without a doubt....mine has 325 watts carrier output, this isolation transformer bunk, is you if plan on dinking around in the rig with a soldering iron, with the the thing still plugged into the wall...
...i have NEVER  had a problem with mine. the damn thing is small, and i cant understand why these class E  guys keep wanting to trash it...

..tim..

..sk..

HA!

That's exactly what my first build was!

Cut out a big hole in the back and bolted on a heat-sink...
Attached a rack-mount front panel, and there it was!

The PWM modulator/power supply was built into a stripped out NCX-5 cabinet, and the toroid transformer and filter caps were in the NCX-5 power-supply/speaker box.


Lot's of homebrew projects are showing up in the old computer cases...
The best built, strongest cases are the old (read.. ANCIENT)  XT and AT boxes.
Very easy to strip-out and recycle into something usefull.
(until they become valuable antiques)
 ;D

Tim, I thought as much.  I don't see how 325 watts fully modulated can be put in something much smaller.  Your matchbox is way bigger than the rig if your freq's are spread out all over 75 and 80.

But it's fun to build stuff too.  The boys are pretty proud of their rigs and experimentation.  Did you get an 80 meter one? What six freq's did you decide on? 

I think I'd go for 3705, 3725, 3733 (what's for dinner net) 3875, 3880 and 3885.
 

It has nothing to do with class E, or anyone trashing anyone.  It's a simple matter of design and performance.  I have designed and built class D transmitters (in fact, I have a major class D project underway now).

This is not a class E/D issue, it is a design and implementation philosophy difference.  The published class E designs have lots of headroom, will produce broadcast quality audio and will modulate to 200% positive - and do it all day.

Remember the old Caltech class E amplifier for 40 meters?  This was not a good design; there was virtually no headroom and the output device was pushed beyond its safe operating parameters.  As a result, there was a high failure rate.

There are also other design issues such as DC isolation (isolation from the AC mains), etc. that have come under discussion.

Its just like buying a car.  The models vary from the Lincoln Town Car to the Yugo  ;)

More than a few of the Class E rigs have crapped out. I can think of several right off the top of my head.  ;D

Many more than a few tube rigs have crapped out too !! ;D ;D ;D   Fortunately, the class E designs and technology has evolved from the very early designs (where such things happened, even to me), to the current designs, which are highly robust and reliable.

The folks who adopted class E early on were pioneers, working in an area with almost no history or past work from which to draw.  The collective work of these forward thinkers has given life to the current designs which are reliable, stable and reproducable.

The early solid state broadcast transmitters were also very failure prone.  Remember the MW1? Today, solid state broadcast transmitters are the standard, with a failure rate lower than their tube counterparts of the past.  It is the same with the solid state amateur transmitters.  They have reached a design maturity level where a properly designed and implemented solid state transmitter should outlast the generation of people using them  ;) 

As with all things, anything designed or built wrong will not work very well or for very long, regardless of what it is!

Some of them crapped out in the last year. I've only heard of one K7DYY rig crapping out. My point is that your contention about the K7DYY rig is incorrect. I have neither a D or E rig, so I don't have a horse in the race. Just an outside observer, stirring the pot. ;)


And I have heard some people trashing the K7DYY rig. One even called it junk.

Stirring the pot - definitely  ;)  You excel at it  ;D  (but that's ok with me!).

I am not aware of any *new* class E designs crapping out, and I think I would know  8)    There are a number of older designs still out in the field that need to be upgraded to cure their reliability problems.  Just like an old Valient, Ranger or other rig, the issues are well known and the owners are not choosing to correct the problems.

On the other matter, I'm not going to comment too much about the DYY rigs.  Suffice to say, I know of a number of problematic experiences.  These transmitters need a design and implementation upgrade.  The basic technology is good, but the implementation is weak.  With a few hundred dollars of components, the reliability would improve significantly, along with the quality of the modulation.

If I went into production with a class E rig of my design, the price would exceed $1500.00 for a 400 watt output transmitter.  The DYY rigs are quite a bit less expensive.  Not perfect, but at least they're making a good effort at doing something which is very, very difficult (introducing a hardware product and making a profit).  I don't know if the market would bear the cost of the more expensive transmitter.... might try it out sometime - maybe a limited run just to see....  8)

Regards,

Steve

Heck, ALL rigs crap out once in a while. Nothing to be ashamed of. In fact, it's a badge of courage...   ;)  There's hundreds of parts in each and countless designs.  The responsibility can lie more on the parts manufacturers than the design. Also, human building errors or operating errors dominate more than original design problems when it comes to crap-outs.  When humans are involved with radio, all rigs are vulnerable to error, (including SS rigs) especially with all the loose variables involved with antennas, changing bands, changing rigs, levels, pushing things too hard etc..

Much depends on how close to the edge you wanna live with your gear.

If we kept a real time listing of rigs that have crapped out on this BB, it would look as random as any other unrelated data sample.

As far as CURRENT E rigs crapping out...  Brentina was on the other night with his new E rig - and it sounded great. He came back PW and said one of his modules had crapped out and he had to QRT to figure out what blew.  Maybe serious, maybe minor, but, what's the big deal?   They ALL crap out once in a while given enuff time... ;D  No rig is immune. Most homebrew rigs are a work in progress, anyway.

T   (CrapOuts-R-Us... and proud of it!)

Bob is using 50% less shunt capacitance than the design calls for.  He and I are well aware of the problem and the fix.  We're just waiting for the parts to arrive.  I am using the *IDENTICAL* transmitter to Bob's, except that I have the correct capacitor values in my rig.  Bob's RF peaks are reaching over 650 volts (on a 900 volt device - not enough headroom), where they should be under 400 volts (as they are in my rig).  When Bob's rig was at my house for final testing, I observed the issue as well.  Once we get the right parts in there, all should be well  ;)

For myself, I hate equipment crap outs  :-\  If something craps out, it means the design or implementation is faulty.  When I build something, I never want to look inside of it again  8)  (well, except to show it to someone!).

Probably being a bit anal here about the reliability thing, but what the heck  ::)  I'd rather be designing something new than fixing something old (and it's old once it's completed and in service - even if only the day before!).   :D :D

Regards,

Steve

..my k7dyy is on 160...never had a problem...very reliable...325 watts carrier, runs all day...the only change i would like to see, is provision for a vfo...it draws 5 amps on tx, barely gets warm....my point was, whenever i talk with a class E  guy, they start slagging the rig, without any delay...i've had the tx for 2 years, and it has never let me down...i think, that says alot...

..sk..

Well,  Tim,  I did try to be very gentle in making my remarks ...

Know of three DYY rigs.  Three of them HAVE had problems.  The most recent one had been back for repair several times that I know of.  Finally,  the buyer of that rig bailed out of it.  (dunno know the exact details)

Rigs can and do fail.  For the DYY rigs,  Bruce has more responsibility in the reliability of the SRs that he builds,  as he BUILDS them.

EDIT:  Hi Tim,  UR post arrived as I was doing this one ... Thanks for the clarifiation -- thought that U were referring to my previous DYY comments as "trashing" --

Regarding the QIX design,  it is just that,  a design.  Others,  usually the user,  builds it.  We can make make a number of errors in our implementation of the design,  but it does appear to be robust.

I do not think that what I have said is trashing K7DYY,  his design,  or its implementation.  I am delighted that you and a number of others have had such success with the DYY rigs.  I do think that a VFO could be used with the DYY rig,  but one would need to gate it off,  as it seems to be a primary control element,  as I recall.

Have Fun !!     73,  C U on AM     Vic

Hi Tim, I've talked with you on 160 with the rig, and as I recall, your DYY rig sounded fine  :)

Any technical talk here or on the air with respect to quality, reliability, etc. is not meant to trash any particular transmitter or design.  These are just technical facts, measurements, etc.  We do this sort of thing all the time; I do it with my own designs if they are found to be wanting !   Anyway, I don't think anyone meant any offense - certainly none from this end over here!!!!!!!!!!!!!!!!!!!!

We might get a bit punchy about the tube vs solid state thing, but no harm there... just boys being boys  ;)   All of this technical bantering will indeed improve the state of the "art", so to speak - and that's a good thing.  Heck, if we couldn't build and design new transmitters, what would we do  ;) :D ;D 8)

The DYY rigs are out there as a real product just like the Rangers, Valients, B & W 5100s, rice boxes, etc... and there is generally talk at some time or another about the various problems in all of these rigs.  They all have something and we seem to like to banty it about!  Even the flex 5000, which I think is a pretty perfect radio, has its issues.

Heck, my company built the AMM-HF1 modulation monitor, and we immediately got requests for new features (which may be incorporated into a future version of the product!).  One thing about that, we never got any returns on the mod monitors which is pretty good in my book, and every customer we talked with loves the product.  But, the monitor went through a 3 year testing cycle before it was released - a bit overkill I admit, but as I said, I'm a bit anal about equipment failures  ::)

Everyone on 160 before the static comes in !  :-)

Regards,

Steve

All kidding aside, my hat off to anyone trying to sell a product in the amateur radio market. Finding the right quality/reliability versus cost/profit point has to be tough. Anyone can make a very high quality, very high reliability product, as high long as cost isn't much of a factor. That's why I never got all the slobbering over Collins engineering. Sure their stuff was good, but it cost way most than most other amateur radio gear. I find the Hallicrafters engineering more amazing. They made some good stuff without the price being ridiculous.

You're right Steve..HUZ..

Any product out there that is manufactured for such a small market, is expensive.
(NOT including stuff from big manufacturers that is)

One of the biggest problems facing anyone who wants to market equipment, is having the financial backing or resources to purchase large enough quantities of parts to keep the price of the product ""within reason".

And then, if you want to make a complete transmitter and market it, you need an FCC tag to put on it.
(just need to leave out a couple minor items to get around that)   ;)

Bruce,

Ain't that the truth.

It's difficult making a go of it in most any manufacturing environment, never mind catering to frugal hams in a very limited specialty market.

One of the true success stories is MFJ.  The founder of that company has been doing it since at least 1978 and continues to come out with new accessories on a regular basis.  Their MFJ-259B antenna analyzer was pure genius. Even I bought one... :-)  Despite the quality issue with MFJ, ya gotta hand it to him for his pricing and marketing skills.... and recent acquistions.

Good luck to you, Steve/QIX, DYY and anyone else trying to make a difference in the AM ham market. 


Tom, K1JJ

Don't know about DYY, but safe to say Steve QIX is not in this for the dollars ;D.  His motivation is the (AM) hobby and that is 'nuf said.  Probably true for DYY too.

The E rigs are challenging to build, never mind design. They are difficult to get "right" and the technology is akin to nuclear versus hydro in the sense that the theories are completly different.  But the results are the same.  I have let the smoke out on a number of occasions...but we won't dwell on that  ::)...the point is these radios are fixable and easy to troubleshoot.  Same can be said of the hollow state homebrews.  I like the homebrew solid state versions...lower B+  8)

Next we need to think about an E rig for the car.  A pleasant thought to think I can light up the dashboard of the car next to me on Rt 128, especially a Prius.  But that's another subject. 

~ps

Layout is very critical in a good solid state rig. A poor layout brings early crap outs.
I just stripped out my first class D final and laughed at myself as I snipped it apart. What a crap layout. TO3 FETs IRF250s on 75 meters. big buck FETs in 1983.