AM QRP Net?

[W1RKW]

It's November.  Any interest in resurrecting the AM QRP (PW) Net?

[KD5HHH]

I am willing to give it a try.

[k7mdo]

I, too, wonder what is the definition of QRP AM.

I have just ressurected an old Heathkit AT-1 with a modulator built into the cabinet that uses a technique of what I believe is grid modulation from about 1955.  I see about 4 watts of 50-60 % modulated AM coming out of it but so far have only made contacts in the 20 mile range on 80 meters.

Wouldn't that qualify as QRP?

Tom

[Pete, WA2CWA]

Most QRP enthusiasts would probably agree that for CW and AM the output power should be 5 watts or less. However, if you're an amateur that typically runs close to maximum legal power most of the time, maybe to them, QRP power is 50 or 100 watts. You can also use the crude measuring approach of putting a #47 type lamp on the output of your transmitter. Key down and modulate the rig. If you don't burn out the lamp within 10 to 20 seconds, you could be considered running "QRP power".

[W2VW]

Most QRP enthusiasts would probably agree that for CW and AM the output power should be 5 watts or less. However, if you're an amateur that typically runs close to maximum legal power most of the time, maybe to them, QRP power is 50 or 100 watts. You can also use the crude measuring approach of putting a #47 type lamp on the output of your transmitter. Key down and modulate the rig. If you don't burn out the lamp within 10 to 20 seconds, you could be considered running "QRP power".

What if the lamp is already burned out?

[W3RSW]

Then you burn up your 2N112 'cause of no load.  

I have a neat little qrp electron coupled osc., one stage cw transmitter using a 6AK5; when I want to go "QRO", I plug a 6AQ5 into the tube socket.  ...the same tube base pin-outs, believe it or not.   The onboard supply is from a Heath VTVM bridge rectified pwr. transformer, plate key up 157 volts, key down 145 volts when using the 6AQ5.  I_P is 18ma. yielding about 3 watts input, hopefully 2 watts output.

 When using a stiffer outboard supply for the 6AQ5, plate key up is 187 volts, key down 165 volts at 42ma, yielding about 7 watts input, 5 watts output. My wattmeter is not very readable at these lower powers and not very accurate at any power.

Here's a pix of the little 6AK5/6AQ5 rig being "super modulated" by a pair of 6146's. Someone serioulsy wrote that I shouldn't do that.      ...as if I even hooked it up (not counting the fake red and black leads, heh, heh. )

"Life's too short for QRP," but if you must, especially AM, then operate on a freq., say 2705, that has a little space from the QRO's and lids.

[KB2WIG]

"say 2705, that has a little space from the QRO's and lids. "

Yep, I've never heard a problem on 2705. And its usally a clear frequency.


klc

[W3RSW]

yep, very clear. 

[W2VW]

Then you burn up your 2N112 'cause of no load.  

Ok. I'll install a 10 dB attenuator in series with the load.

[KF1Z]

yep, very clear. 

"say 2705, that has a little space from the QRO's and lids. "

Yep, I've never heard a problem on 2705. And its usally a clear frequency.


klc

Yess..

Except for the occaisional navigation beacons etc...

[Ralph W3GL]

I think (what, me think!) RSW meant 3705 but believe me,
there's QRO and Lids there too...    

Sometimes not even from the USA, as well...  

[Pete, WA2CWA]

I think (what, me think!) RSW meant 3705 but believe me,
there's QRO and Lids there too...    

Sometimes not even from the USA, as well...  

High power makes it go away.



It's tiresome to keep yelling out "can you hear me now?"

[Steve - K4HX]

The power level you can get away with depends on the band and frequency, time of day, your antenna and those of the guys on the other end, and of course the distance(s) involved. For 80/75 meters in the late afternoon and stations within a few hundred miles, 5-10 watts should work FB more often than not.

[Opcom]

I think (what, me think!) RSW meant 3705 but believe me,
there's QRO and Lids there too...    

Sometimes not even from the USA, as well...  

High power makes it go away.



It's tiresome to keep yelling out "can you hear me now?"

Geez Pete, what is that beast? a werewolf-cat-head-mullet-guy? Scary monsters, super freaks!

[AJ1G]

I'll have to torture everyone with the AN/GRC-9 PW mobile, I've had a few QSOs with TimTron and others with it a few Saturday mornings of late on 3885 and 7290

[W3GMS]

I'll have to torture everyone with the AN/GRC-9 PW mobile, I've had a few QSOs with TimTron and others with it a few Saturday mornings of late on 3885 and 7290

Great Mobile setup Chris!  Love that military gear well mounted in your truck!

Joe, GMS

[W3GMS]

It's November.  Any interest in resurrecting the AM QRP (PW) Net?

Bob,
I just bought a Retro 75 along with the Retro Helper VFO.  Small Wonder Labs has discontinued both items but I found a Retro on QTH.com still in the shipping box ready to be built.  It will be a fun kit project!
73,
Joe, W3GMS 

[AJ1G]

Thanks  Joe...don't tell my wife but I have been thinking about how I can add a 24V battery and alternator and put the AN/GRC-19 back in there so I can strap with Nicky Badwires in the Hummer.

It was a very easy install to run the radio power and antenna wiring into the Tacoma cab.  There are some big holes with rubber plugs in the floor pan just behind the seats that seem like they were made for radio installs, or more likely high power stereo systems.  I have the DY-88 for the GRC-9 sitting behind the driver's seat.  The ignition noose with the engine running is very low, even without a noise blanker.  The photo shows the hamstick clone antenna mounted on one of the Tacoma tie down cleats, I just bolted it into one of the existing 1/4 inch holes in the cleat that I drilled out to 3/8 inch.  I since have installed two small Hustler ball mounts on L brackets that I scored at NEARFEST.  The holes in their brackets were spaced perfectly for the pairs of bolts on the top of the stanchions just forward of the tailgate.

[W1RKW]

It's November.  Any interest in resurrecting the AM QRP (PW) Net?

Bob,
I just bought a Retro 75 along with the Retro Helper VFO.  Small Wonder Labs has discontinued both items but I found a Retro on QTH.com still in the shipping box ready to be built.  It will be a fun kit project!
73,
Joe, W3GMS  

Hey Joe,
Yes, I heard SWL dropped the Retro.  Just before Dave discontinued it I was fortune enough to get a Retro 40. I have both the 40 and 75 now.  Both are modified with improved audio too.  I have yet to put the Retro40 on the air.  I stopped working on it last winter.  But will pick up soon to finish it off.

WD5JKO has some audio mods he posted last year or the year before here on AMFone.  I did some of his and did my own. Also swapped out the mod transformers with something beefier.

Also made a receiver mod to increase sensitivity. Got a few other receiver mods in the works too.

So this begs my original question who is interested in resuming the AM PW net on Sunday afternoons?

[W3GMS]

Hey Joe,
Yes, I heard SWL dropped the Retro.  Just before Dave discontinued it I was fortune enough to get a Retro 40. I have both the 40 and 75 now.  Both are modified with improved audio too.  I have yet to put the Retro40 on the air.  I stopped working on it last winter.  But will pick up soon to finish it off.

WD5JKO has some audio mods he posted last year or the year before here on AMFone.  I did some of his and did my own. Also swapped out the mod transformers with something beefier.

Also made a receiver mod to increase sensitivity. Got a few other receiver mods in the works too.

So this begs my original question who is interested in resuming the AM PW net on Sunday afternoons?
[/quote]

Bob,
I would be interested in any mod's you come across on the Retro.  Feel free to send them to my email address if you care to.  I do remember here on AMfone  folks were discussing the rig in great detail.  I did not realize the Dave had one that would cover 40 meters.  I will build mine stock first and then go from there concerning any possible mods.   

Joe, GMS

[W1RKW]

Joe,
This is the thread that discusses Jim's (JKO's) mods: http://amfone.net/Amforum/index.php?topic=24493.0   If you go into page 2, I think that's where the nitty gritty details are.

 I did not do all of Jim's mods but simply added capacitors in various stages which improved audio immensely.  The rig has a peak limiter. I disconnected that simply by disconnecting the peak limiter LED. The peak limiter limits modulation to about 75%, maybe a little less.  With the peak limiter disconnected, I watch the modulation on a scope especially when I run the 25watt SS amplifier. It's not that critical at 2 watts but I do it at that level too.  Jim also has some mods to the peak limiter that improves modulation.  He's done some work with different type of transformers too.  I didn't go down this road but did install one of these:  http://www.hammondmfg.com/102.htm   Cat No. 106R.   It's response is a bit better as well as power handling.  I've smoked the stock transformer. I forget how I did that but it doesn't like a gob of DC running through it. It's form factor is not the same so I mounted it off the PCB with jumpers. I modified the receive side to include an RF preamp to improve listening sensitivity. Last year I started working on a IF AGC scheme with S meter but haven't had the time to finish it. My Retro 75 I mounted on a 9x12 chassis. The Retro 40 is in the SWL cabinet with the same audio mods. The receive mods might be a bit trickier due to switch relays and extra wiring but I think it's do able.