[Hammarlund] HQ-180 sounding right?

[Roger D Johnson]

Not quite. The AGC and audio bandwidth are completely separate circuits. The 
audio has a
negative feedback circuit that decreases the audio bandwidth as the volume 
control is advanced.
The theory being that weak signals will have the volume turned up more and will 
benefit from a
narrower bandwidth. Many sets have this feature defeated as most think the audio 
sounds better
without it.

73, Roger


On 9/25/2014 1:05 PM, Glen Zook via Hammarlund wrote:
> According to the HQ-180 manual, there is a 4-position AVC/AGC switch.  The positions are off - slow - medium - fast.  However, again according to the manual, there is an auto response circuitry that widens and narrows the audio bandwidth depending of the strength of the signal.  That is, with a strong signal the audio frequency response is wide but, as the signal strength decreases, the audio frequency bandwidth gets sharper and sharper.
>
> There may be a problem in this circuit.
>
> Glen, K9STH
>
> Website:  http://k9sth.net
>
>
> On Thursday, September 25, 2014 11:28 AM, Kenneth G. Gordon<kgordon2006 at frontier.com>  wrote:
>
>
>
> On 24 Sep 2014 at 19:55, Robert Sauvan wrote:
>
>> Wow,
>> Thanks for all of the replies. I will sort through everything to see if
>> I may find the problem. I will try the replacement of the v8/v16 since I
>> think I have extras. SSB seems to be OK. CW signals just seem to be way
>> to "sharp" for lack of a better term.
> Well, as several of us have mentioned, your AGC circuit seems to be the
> center of the problem. Two others suggested that the AGC circuit may not be
> working at all, at least in CW. After thinking about this a bit more, I agree.
>
>> I do not have access to Electric
>> Radio magazine but I will see if I can find one as Ken W7EKB suggested.
>> It would be a good article to read.
> You might give Ray at ERMAG.COM a call and see if you can buy the single
> issue. I am sure he would be happy to oblige.
>
>> Will let everyone know if I come up
>> with something to cure the issue. Sounds like I might not be crazy
>> thinking something may be wrong with the radio..
> No. You're not. There IS a problem.
>
> Ken W7EKB
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