Does QRP AM make any sense?

[VE3GZB]

Now that my Kenwood seems to have gotten sick, I was thinking of cobbling together quickly something for use until I can get the Kenwood figured out.

I do have projects on the go, but projects take me a lot lot longer these days to do than in the past.

I know that I can work nearly cross country on 20 and 17m with less than 30W, even as little as 5W seems to work wonders depending on the band and conditions.

But that's with SSB. What about AM? A quickly cobbled together breadboard rig would probably be only AM. To work 20 and 17m bands how much AM power would realistically be required to work cross country?

Thanks and 73s,
geo VE3GZB

[KD6VXI]

George,

On 10 and 12, I've used a Cobra 29 LTD Classic.  It does about 4.5 watts of carrier, and PEP close to 20.  Negative peak limiter included   2SC1969 as the final amplifier.

I use an MFJ259B as the 'VFO'.  Feed a 14-16 mhz sig into the tripler input (it takes 10.240 mhz / two,  then  triples thats to a 15 mhz feed for 11 meters).

So, to answer your question, a 5 dollar radio on craigslist got me on 10 and 12, and I had a BALL with a real antenna on it.

And no, the MFJ is NOT a replacement for a real VFO, it's got a modulated output.  The PLL in the radios I used doesn't care, it's only used as a reference sig.


--Shane
KD6VXI

[W1RKW]

Why not? The Retro 75 and REtro 40 can do the job at a couple of watts each depending on conditions.  All one needs is a good antenna.  Under high static levels why waste your time with QRP AM.

[Ed/KB1HYS]

Well, I can't speak directly to the higher bands, but the QRP AM net that was running last winter had good coverage here, with stations from all over New England & New York checking in with anywhere from 15 watts and down.  I could copy almost everyone when ever I listened in.

[VE3GZB]

....I use an MFJ259B as the 'VFO'.  Feed a 14-16 mhz sig into the tripler input (it takes 10.240 mhz / two,  then  triples thats to a 15 mhz feed for 11 meters).....

ROTFLAMO! That's the first time I ever heard of such a use for that, very clever!!

73s geo

[W2PFY]

ROTFLAMO

I know exactly what you mean

[WU2D]

We will re-energize the AM QRP activity as the noise mitigates this Fall. The timing of the QRP Net was perfect for short hop work and stations were easy to copy, some running only 500 mW. My QRP rigs were a 50C5 modulated by a 50C5 and a 6AG7 suppressor grid modulated with a transformer and carbon mic. There were all kinds of crazy rigs on from Software defined to cakepans. Lots of fun.

Mike WU2D

[KM1H]

I run AM at times with an early and late Meissner Signal Shifter but on 40 and up; havent even attempted 160/80. Modulated by 6005's. Worked WAC on 10 and 15.

Carl

[KD6VXI]

....I use an MFJ259B as the 'VFO'.  Feed a 14-16 mhz sig into the tripler input (it takes 10.240 mhz / two,  then  triples thats to a 15 mhz feed for 11 meters).....

ROTFLAMO! That's the first time I ever heard of such a use for that, very clever!!

73s geo

It gave me the idea to get a DDS.  The MFJ drifts SO bad it isn't funny.

BUT, it DID give me the 'proof of concept'.  Most of the AM only radios will retune JUST fine to 12 meters. 

I'm going to try 15 next time I'm playin with it.

[k4kyv]

Life's too short for QRP.

[xe1yzy]

We will re-energize the AM QRP activity as the noise mitigates this Fall. The timing of the QRP Net was perfect for short hop work and stations were easy to copy, some running only 500 mW. My QRP rigs were a 50C5 modulated by a 50C5 and a 6AG7 suppressor grid modulated with a transformer and carbon mic. There were all kinds of crazy rigs on from Software defined to cakepans. Lots of fun.

Mike WU2D

Very nice rig Mike, congratulations!

[VE3GZB]

Actually QRP can be fun!

So far on 20 watts I worked Missouri and Kansas, on 10 watts I've worked Montana and Florida, On just 5 watts I've been able to communicate to Idaho, Mississippi, Florida, Massachusetts. On just 2 watts I was able to communicate to Massachusetts, Arkansas & Iowa.

And I was just barely audible in Florida that same evening on just 2 watts though my antenna is fixed-aimed East-West.

I do have a linear now, I got it from a ham in Quebec. I don't use it often because the presence of CATV lines so close to the south side of the house - where my antenna mast is - makes TVI a bit of a risk. And working constantly in high power is also illegal (hams should always use the minimum amount of power to conduct communications).

But working an RA or a ZL needs more hamsters on the treadmill.

73s geo

[kb3ouk]

i never did like that minimum amount of power necessary rule, just how do you judge the minimum amount of power? the more power you run, usually the better you are heard. so do you run enough power to be just barely heard or do you run enough for it to be comfortable to listen to? there are some situations such as when trying to run AM in high static when the minimum amount of power needed to communicate is the maximum you can put out.

[Todd, KA1KAQ]

I seem to recall a very similar question posed and lengthy discussion here when you built that QRP breadboard rig for 40m(?) a couple years ago, Geo. The same principals still apply.

[Opcom]

Some of the folks on the Texarkana Traders Net run only 15-25 watts of carrier and are heard well. These are usually old military rigs which have plenty of 'talk power' and I presume their antennas are high and well-made.

I can't get away with 20W from the ricebox and have to use 100W carrier. It may be the time of day, frequency, and antenna, which seem to have more to do with it than the power level itself.

[The Slab Bacon]

Life's too short for QRP.

Agreed, fully, 100%

QRP AM, especially on a noisy night makes about as much sense as a fart in a space suit! ! !  And if you are running a compromise antenna, you are really fighting a losing battle. You might get away with QRP AM on the higher bands like 10m, but on 75 and 160 it's.......................

"BANG, lookie here, squashed just like a bug"   

[kg8lb]

 QRP can work quite well, even on 75 AM. Of course the conditions need to be tasken in to consideration. It is not for everyone but there are quite a few having fine results . Had quite a few rag chew QSOs at distances of up to 600 miles, using the Retro 75 , 2 watts prime time on 75. Even with the wide barges (They think of themselves as "tall ships" operating in the area !
   Go for it !

[The Slab Bacon]

QRP can work quite well, even on 75 AM. Of course the conditions need to be tasken in to consideration. It is not for everyone but there are quite a few having fine results . Had quite a few rag chew QSOs at distances of up to 600 miles, using the Retro 75 , 2 watts prime time on 75. Even with the wide barges (They think of themselves as "tall ships" operating in the area !
   Go for it !

Y'all QRPers need the "wide barges" to keep it clear for y'all and blast a hole so the slopbuckets dont squash ya like a bug.................   

[WD8BIL]

Sure it'll work real well. I've use the Drake T4X barefoot (20 watts) every weekend on 80&40 with good reports. It's a lot of fun.

But chose your op times and freqs carefully. You don't wanna run a motorized skateboard on the interstate at rush hour.

[wa2dtw]

If 10 meters opens again, then QRP AM might work on that band.

[W1FVB]

It's a lot of fun.
My homebrew creation does 2 W on 80M and I'm frequently surprised on how well it does.
Make sure to modulate it well. I've heard a few QRP'ers on the NE QRP net this winter that could use a little bit more audio. The next TX on the bench will hopefully be doing about 40 W.. which is still QRP for a lot of you guys  

Frits

[kg8lb]

QRP can work quite well, even on 75 AM. Of course the conditions need to be tasken in to consideration. It is not for everyone but there are quite a few having fine results . Had quite a few rag chew QSOs at distances of up to 600 miles, using the Retro 75 , 2 watts prime time on 75. Even with the wide barges (They think of themselves as "tall ships" operating in the area !
   Go for it !

Y'all QRPers need the "wide barges" to keep it clear for y'all and blast a hole so the slopbuckets dont squash ya like a bug.................    

Nope, never needed "wide barges" that I can recall. Positively never wanted one.
 When conditions are good , QRP works FB. The wide barges are no more trouble than the sidebanders. We worked Steve , WA1QIX on Rattlesnake Island last Sunday with the Elmac @ 37 watts with 20 over 9 sig reports. I am certain the Retro would have worked pretty well .

  Mike, N8SDD lives a few miles away.  We often zero beat the  wide barges with our Retro 75s and talk right thru them .   So , even when the band is sufferring from an east infection we are able to operate 75 AM quite easily. 20 meters should be just as viable.

Of course QRP isn't for everyone . Many others however have had fine results with a decent QRP station.

 Sure, QRP will work on 10 . It also works well on 75  

[iw5ci]

Yes! just today i have done a very nice qso with the setup you can see.... my recently restored HW TBC-50C i received very good reports!

20W carrier.

[KB2WIG]

Its all in the antenner..... the better the antenna, the better you'll get out.


Is the 'wide barge' like the 'wide stance'  ? ??

klc

[K5UJ]

Miscellaneous thoughts on QRP:

A rich man once said, "I've had low power and I've had high power and believe me, high power is better."   

In my first salad days as a ham, I recall seeing messages in QST advocating low power repeatedly.  Editorials, articles, occasional opinions by columnists all saying no one needs to run more than 100 watts blah blah sprinkled through issues of QST once or twice a year for years on end.  At the same time, I'd see ARRL staff members' shack photos in contest results and there'd be a SB220 in nearly all of them.  Hmmmm.  It took a few years to start feeling like a sucker. 

I wonder why all the sw and mw broadcast stations aren't running 20 watts.

I like armchair copy and am glad the station I'm working is running a T368.  I can also hear my 20 watts Q5 no problems.  What else matters.