TUNING AMPS/DUMMY LOAD

[Stellasstillarat]

when an amps tuned up on antenna A then switched to antenna B should your amplifier be returned to antenna B?
I've read so many postings suggesting that one should tune their amplifier using a dummy load.
Then remove the dummy load and hook your stations antenna up.
Wouldn't this most likely put the amp out of resonance as the antenas readings (swr/ref power) will differ from the readings you original tuned the amp to while using a dummy load?
Or is it just the transmitted power input to the amp that puts an amplifier in resonance?
And changing from dummy load to antenna or antenna A to B will not or should not change the amps resonance?

Another nutty question from Stella. Thanks.

 

[Atlasta]

I use DL's for tuning up for two reasons:

1) It provides a known constant load, and

2) It doesn't tie up the frequency.

People who tune up on center frequency have always been a pet peeve of mine. I mean c'mon: If you truly lack the funds to buy or the wherewithal to build your own DL, at least move a few KC off center freq when you tune up. That's just good radio practice.

Assuming the two antennas have the same load characteristics the amp shouldn't need retuning just because you switched antennas. The amp is looking for a 50-ohm load. It doesn't know whether that load is a DL or a live radiator.

 

[wavrider]

YES you need to tune again.

Most tube type amplifiers with variable caps will work into a 2:1 vswr.

No need for a 50 ohm perfect impedance ( would be nice though)

Tuning into a dummy load will get you in the ball park of where you need to be.
Then connected to the antenna a little adjusting of the antenna tune cap should get you where you need to be for output.

Captain Kilowatt has a sticky thread somewhere around here ( maybe in the sticky section)

Of how to tune an amplifier

 

[DainBramage]

I use DL's for tuning ...
People who tune up on center frequency have always been a pet peeve of mine...at least move a few KC off center freq when you tune up. That's just good radio practice.....

... and what about the people that are operating a few Kc away from "center freq" (whatever that is)?

when people tune up on a freq that I am USING, and then I immediately see the same signal a few Kc up the band on my panadapter, I make a point of returning the favor.

thats about the same as the people that work split,... and NEVER listen where they are transmitting first, they just dial in a split and QRM whoever may be "up 5".

 

[Atlasta]

Was not referring to tuning up on amateur frequencies, just on CB.

On CB I try to stay on the in-between frequencies (such as 27.195 or .145) or at least on the 'zeros' instead of the 'fives'

Always good practice to tune around the desired frequency to make sure that no one else is there.

Or, just use a DL.

 

[wavrider]

[QUOTE="DainBramage,

when people tune up on a freq that I am USING, and then I immediately see the same signal a few Kc up the band on my panadapter, I make a point of returning the favor.

thats about the same as the people that work split,... and NEVER listen where they are transmitting first, they just dial in a split and QRM whoever may be "up 5".[/QUOTE]

You intentionally QRM a QSO?

 

[Stellasstillarat]

I live in an area with one channel that used by all locals. And it's not 20.
I tune on channel 20 where the stations I occasionally hear barely have a readable signal.
Even if there on the air I go ahead and tune up.
If I knew I was going to interfere with anyone on that channel I would just break in and ask if anyone would mind if I used the channel to tune (which takes me about 40 seconds). Their so far off in the distance I know I cause no probles interfering with their rag cchewing. They most likely don't even know I'm there.
If the case were reversed I'd have no problem with any of them tuning up as they in no way could cause ininterferance with my local qso.
Im talking 70-80 miles away.
If the only reason to tune an amp using a dummy load is not to interrupt others qso's I'll just go ahead an continue to tune on channel 20 while hooked up to the antenna.
I actually have learned not to continually re turned my amp.
If everything stays the same meter reading wise I dont touch the amps except to hit the on and off switch.
if there's an advantage to tuning up using a dummy load please do tell.
I don't know where you operators live but it sound like you have many locals on many channels. Reminds mr of the cb craze. 25 people on every channel. Not here. About 7 locals all on one channel. If your lucky three might be on the air at the same time.

 

[543_Dallas]

Was not referring to tuning up on amateur frequencies, just on CB.

On CB I try to stay on the in-between frequencies (such as 27.195 or .145) or at least on the 'zeros' instead of the 'fives'

Always good practice to tune around the desired frequency to make sure that no one else is there.

Or, just use a DL.

Tune it up one time and leave it alone. It doesn't take long and you can do it a few channels away from where you talk. The guys that get on people's nerves are the ones that think they need to retune weekly. You need to tune the amp into the load it will be ran into...the antenna. If you've just built or bought the amp test it out on a DL and then do the final tuning on the antenna.