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When do you use fast AGC?

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Jeff-229

When do you use fast AGC?

Hi gang,

The K2 is the first rig I've had that has adjustable AGC. Under what conditions would one benefit from using fast AGC? It seems that slow AGC is easier on the ears on CW.

Thanks & 73,
Jeff
WB5GWB
Long Island, NY
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Geoffrey Mackenzie-Kennedy-2

Re: When do you use fast AGC?

Hi Jeff,

Putting aside not using AGC at all, whether you use fast or slow AGC for
either CW or SSB depends on how quickly you want the receiver to recover its
full sensitivity after being smacked by a strong signal. The 'fast' and
'slow' refer to recovery time. In a DX pile-up situation when using AGC I
prefer to use 'Fast' so as not to miss any short transmission from the
victim such as 'agn', especially when the signal is weak in or close to the
noise and he sends immediately after a bunch of stations with strong signals
have finished calling. 'Slow' AGC is easier on the ears when ragchewing or
if the DX station is reasonably strong, or when there are strong bursts of
storm QRN, but my personal preference is to use 'Fast' all the time when
using AGC.

73,
Geoff
GM4ESD

----- Original Message -----
From: "Jeff" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, October 15, 2006 2:00 AM
Subject: [Elecraft] When do you use fast AGC?

> Hi gang,
>
> The K2 is the first rig I've had that has adjustable AGC. Under what
> conditions would one benefit from using fast AGC? It seems that slow AGC
> is easier on the ears on CW.
>
> Thanks & 73,
> Jeff
> WB5GWB
> Long Island, NY

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Tom Hammond-3

Re: When do you use fast AGC?

In reply to this post by Jeff-229

Hi Jeff:

>The K2 is the first rig I've had that has adjustable AGC. Under
>what conditions would one benefit from using fast AGC? It seems
>that slow AGC is easier on the ears on CW.

FAST (or OFF) AGC is the only setting is EVER use on CW!

If you only work the 'strong ones', then using SLOW AGC will work
well for you. However, if you work weak stations with SLOW AGC
enabled, you'll find that a strong nearby station can (and often
will) 'pump up' the AGC, thus REDUCING IF GAIN, to the point that the
weak station will either drop significantly in signal level, or
possibly completely disappear until the strong in-band signal is gone.

Additionally, using FAST or OFF AGC will give you a 'sharper
sounding' CW note, which can be more easily copied, especially at
higher speeds.

You'll have to ask a phone operator about using FAST/SLOW AGC on
SSB... I have little experience there... <G>

73,

Tom Hammond N0SS

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Ron D'Eau Claire-2

RE: When do you use fast AGC?

I do use "fast AGC" at times but I'm basically a "non-AGC" CW operator
unless I'm just casually tuning around and chewing the rag with stations
with good strength. I don't appreciate listening to band noise that is
greatly amplified above its real level. If a signal is 20 dB above the
background noise, I want to hear it standing out 20 dB above the background
noise. But AGC works hard to make the background noise as loud as the
signal.

I guess that's a valuable feature in marginal conditions where you're trying
to hear a weaker signal that may send only an element or two after a much
stronger signal finished sending, provided there isn't another signal in the
passband killing the gain as Tom observed. It saves having to "ride" the
gain control manually, but I find AGC extremely irritating under those
conditions - like trying to operate with a loud vacuum cleaner (a "Hoover"
to our friends in England) roaring next to me in the shack as the background
QRM is pulled up to full volume whenever the signal is not present.

So I use either AGC slow for casual operating or no AGC at all and ride the
gain manually, especially if I'm digging for weak signals.

So when do I use "fast" AGC? When I'm listening to a strong AM signal on the
K2 that has significant QSB. The fast-acting AGC follows quick changes in
the carrier level more closely. That's true of PSK or other digital modes in
which there's a steady carrier present as well.

Ron AC7AC

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Karl Larsen

Re: When do you use fast AGC?

In reply to this post by Jeff-229

Jeff wrote:
> Hi gang,
>
> The K2 is the first rig I've had that has adjustable AGC. Under what conditions would one benefit from using fast AGC? It seems that slow AGC is easier on the ears on CW.
>
>
Most new radios have this feature Jeff. Back when there was just
Fast AGC or No AGC we used AGC on AM phone and No AGC on CW. This was
back in the 1950's when you had a transmitter in one box, and a receiver
bought seperate, or once in my life built for myself.

Today because I'm very old I do CW either with Slow or No AGC. When
you use No AGC you turn the RF gain to zero, turn the audio gain to full
On, and then slowly increase the RF gain until you hear it as you want
it. This method has a lot of plus features. It makes your bandpass
filter work better, and your wife will insist you use earphones :-)

Fast AGC is for AM phone stations.

72 73 Karl K5DI

> Thanks & 73,
> Jeff
> WB5GWB
> Long Island, NY
>

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Rolf Moberg

Re: When do you use fast AGC?

>> The K2 is the first rig I've had that has adjustable AGC. Under what
>> conditions would one benefit from using fast AGC? It seems that slow
>> AGC is easier on the ears on CW.

When receiving very weak, fading cw signal you could benefit by
switching AGC fast.

Rolf
oh6kxl
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k6dgw

Re: When do you use fast AGC?

In reply to this post by Jeff-229

FWIW: I use fast AGC on CW, and either med or slow on the rare times
I'm on SSB. In a QRM-free situation with either slow or no QSB, med or
slow AGC is probably a bit easier on the ears. However, in rapid QSB,
the AGC doesn't recover fast enough and the signal falls below the
threshold of my very poor hearing. Likewise, in QRM and very close
strong signals, I find the fast setting to be best. YMMV

Fred K6DGW
Auburn CA CM98lw

Jeff wrote:

> Hi gang,
>
> The K2 is the first rig I've had that has adjustable AGC. Under what conditions would one benefit from using fast AGC? It seems that slow AGC is easier on the ears on CW.
>
> Thanks & 73,
> Jeff
> WB5GWB
> Long Island, NY
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
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Bob Nielsen

Re: When do you use fast AGC?

I do likewise. If the QRM is close in frequency and strong enough to
pump the AGC. I typically disable AGC by turning the AF gain to max
and using RF gain as a volume control (just like I did in the old
days of simple detectors and fixed AGC).

Bob, N7XY

On Oct 15, 2006, at 3:49 PM, Fred Jensen wrote:

> FWIW: I use fast AGC on CW, and either med or slow on the rare
> times I'm on SSB. In a QRM-free situation with either slow or no
> QSB, med or slow AGC is probably a bit easier on the ears.
> However, in rapid QSB, the AGC doesn't recover fast enough and the
> signal falls below the threshold of my very poor hearing.
> Likewise, in QRM and very close strong signals, I find the fast
> setting to be best. YMMV
>
> Fred K6DGW
> Auburn CA CM98lw
>
> Jeff wrote:
>> Hi gang,
>> The K2 is the first rig I've had that has adjustable AGC. Under
>> what conditions would one benefit from using fast AGC? It seems
>> that slow AGC is easier on the ears on CW.
>> Thanks & 73,
>> Jeff
>> WB5GWB
>> Long Island, NY
>> _______________________________________________
>> Elecraft mailing list
>> Post to: [hidden email]
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft Help: http://
>> mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
> _______________________________________________
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>