Greetings!
So I’ve been playing around with my new Galaxy DX-94HP I bought from Bells CB and hooked up my average-reading power meter to look at the output. It swings backwards.
Ok, turn down the power - then does is still swing backwards?
This is a 6 of 1 1/2 dozen of the other - with 13th one for Free on Tuesdays...
So, todays your day...
I've taken radios like the 94 onto several different meters in the shop to show someone - and waste a lot of time getting them to understand - the differences between RMS, AVG and Peak.
Some people understand that CARRIER power - when it's set to Proper Mid-Point for a circuit (thinking steady state) then Modulate it, some of the 50 - 50 is higher while others is lower and carrier is lost into the bandwidth somewhere...they feel they are getting gypped from NEGATIVE swing until you bring them to the Peak power meter...
It's the shift from Carrier to Audio that seems to throw a wrench into the works - because it's not the radio - it's the METER that is trying to sort this all out...
You really need to understand the SAMPLING circuits many SWR/Power meters have and then compare them to AVG, RMS and Peak - power meters sampling circuits - and you'll see several differences in the basic circuit.
What does SWR have to do with this?
Good question in a radio with a built in SWR meter - the FWD power setting is also the S/RF meter power too. So it samples, rectifies, measures and "weighs" the signal one way, while an external meter may use a different circuit method to accomplish pretty much the same thing.
All of them take power from the radio thru a sensor, but what that sensor does with it afterwards makes this a difficult method to talk about because not many people "Get it" when it comes to signal processing and how sampled power is weighted and measured or "bridged" and the complex vectors audio envelope adds to this...
Some use heavy capacitance to "tame" wildly swinging envelopes full of audio and others simply rectify and let the meters own coil d'arsonval movement construction design and inertial "effect" take over and show what is going on in there...some are digitals re-worked to show analog - with that, there's Linear versus Logarithmic response...within the digital realm - and even that's open for interpretation...
Do I just need to back the AM carrier settings down to 5-35W and maybe back off the AMC a little?
Thanks!
In a word, yes.
Do what is comfortable for you. It's not the fault of your radio - nor that of the operator - the meter is not faulty either - they are all working - but just not on the same circuit ... which adds to the interpretation problem...
IF you want a quick demonstration - locate the mod limiter "pot" in there and tweak that - one direction you have your negative swing - the other direction you start to or lessen it's swing - you'll SEE the "negative swing" is less - but you HEAR the audio is processed and "flat" - the limiter effect - you re-open the modulation limiter control to the original setting - you see negative swing again...again...nothing wrong with your equipment none of it - just how it displays it makes you think you have something wrong with it...
Again, if you don't feel comfortable with current settings, it doesn't hurt to turn it down a little and may extend the life of the radio and your enjoyment of it - longer, if you keep the power down and back off the throttle a little bit.
Be conservative first until you are more comfortable - then run it any way you wish...
Regards!
:+> Andy <+: