[amsat-bb] Re: QRP re deux

Michael Heim kd0ar at sbcglobal.net
Sat Dec 20 04:51:15 PST 2008

I'd like to weigh in on this topic with my 2 cents worth, being a long time QRP operator on various bands and modes...

I think QRP means soething different depending on what kind of operating you do.  On HF, its generally 5 watts into a simple antenna, such as a dipole or vertical.

HF digital, there isnt much of a distinction (psk31) as many run 5 watts into a dipole vs maybe 20-30 watts into a similar antenna for QRO?

I operate VHF and microwave.  to me, on 2m SSB tropo, I consider QRP to be 5-10 watts into whatever and however large an array you can muster, as most QRO stations run 50 watts or more into a similar antenna.

EME ops typically defines QRP as anything under about 500 watts or so into a single yagi. (no matter how large that single yagi is)

Meteor Scatter I've been called QRP running 50 watts into 10 elements.

However, on 10 GHz, I run 2 watts into a 18 inch offset fed dish, and I do NOT consider myself QRP.  I'm an "average powered station" with that setup.  When I ran 200 mW into the same dish, it was questionable even then if I could consider myself QRP.  2 watts = about 2-4KW ERP, 200 mw -= 200-400W ERP.  (I havent actually MEASURED the gain, this is calculated ERP)

QRP is a relative term.  Depending on what kind of operating you do, ERP certainly does take into account whether you're QRP or not.

I think in the satellite realm, I would understand QRP to be 5 watts or less into a low gain antenna.  Maybe I'm wrong about this, as I'm still a relative newcomer, however  This puts everyone on an even keel as far as someone stepping over another to make it fair for everyone.  I know there are operators on the main channel that might tweak up the power to get thru on a busy channel.  I know, because I have when I started out.  I have realised it wasnt right, and now my power stays at 5 watts on the 857.  Do i consider myself QRP on AO-51?  well, with my homebrew 3 ele/6 ele V/u antenna on a fixed elevation mount, yea, at times I do, when running 5 watts.  I actually have LESS antenna gain than someone would have with a handheld yagi because the antenna is hardly ever pointing right at the bird.

The QRP channel does provide some interesting experimentation like what Tim, N3TL and others have done, exploring "how low can you go" and still make contact.  To me, THAT is the kind of experimentation that seems like a logical purpose for the "QRP" channel.

As a side note, hasnt the rule always been to run just enough signal to achieve a downlink of reasonable quality?  I remember this from my AO-10 days.  Too much power on an SSB bird robs power from everyone.  Too much power on an FM bird robs others from getting in.
 Michael Heim
Chief Engineer, Forever Broadcasting
New Castle PA

----- Original Message ----
From: Sebastian <w4as at bellsouth.net>
To: AMSAT BB <AMSAT-BB at amsat.org>
Sent: Friday, December 19, 2008 11:10:45 PM
Subject: [amsat-bb] Re: QRP re deux

I agree 100% with you Jim.

If you look at it another way.  Standing on relatively flat terrain  
with 5 watts from an HT on a simplex channel will give you a mile or  
so on FM.

That same 5 watts from the same HT at the Empire State Building  
observation deck will give you coverage to several miles, if not  
several states.

Either of those two scenarios, I consider to be QRP.

73 de W4AS

On Dec 19, 2008, at 6:49 PM, Jim Danehy wrote:

> the premise that I follow is that QRP in the ham fraternity for  
> decades prior to AMSAT was 5 watts output from the final stage of  
> the transmitter . . .  any other attempt which hopes to replicate  
> that simplistic approach is speculation based upon a dynamic that is  
> flawed from lack of accurate measurements . . . and constantly  
> changing parameters . .
> Jim W9VNE
Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
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