Audio levels in K2
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Hello All,
I was chasing DX on the low end of 10m yesterday (good paths to VK!) and noted that even with phones on, I had the AF gain all the way up...and could use more. Perhaps this was due to the headphones I was using, but I wonder if others have noted the same thing. I think this is the only rig I've got that does not have enough AF gain to blast me out of the phones. On vy strong sigs, I don't need the gain, but on the very weak ones, I could use more. Thanks for your insight John K5MO --- Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04 _______________________________________________ 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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Hi John
This has been an ongoing observation from the beginning of the K2's life. It seems the audio amp is very sensitive to the headphone impedance and efficiency. Some folks have very low audio and others seem to do just fine. I get my best results with some old large Radio Shack headphones that completely cover my ears and have small speakers in them. I guess the combo of impedance and efficiency must be a good match for the K2 in these old cans. You might haunt your local ham swaps and pick up a few different headsets for cheap and try them. Good luck and 73 Bob N6WG _______________________________________________ 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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In reply to this post by john-477
I use a pair of Sony 32 ohm phones and have
plenty of audio out of the K2. 73, Doug W6JD ----- Original Message ----- From: "john" <[hidden email]> To: <[hidden email]> Sent: Sunday, October 10, 2004 4:01 AM Subject: [Elecraft] Audio levels in K2 > Hello All, > > I was chasing DX on the low end of 10m yesterday (good paths to VK!) > and noted that even with phones on, I had the AF gain all the way up...and > could > use more. > > Perhaps this was due to the headphones I was using, but I wonder if others > have noted the same thing. I think this is the only rig I've got that does > not have enough AF gain to blast me out of the phones. > > On vy strong sigs, I don't need the gain, but on the very weak ones, > I could use more. > > Thanks for your insight > John K5MO > ---------------------------------------------------------------------------- ---- > > --- > > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04 > ---------------------------------------------------------------------------- ---- > _______________________________________________ > 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 _______________________________________________ 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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We've been over this topic many times. If you go thru the reflector
archives you find that most of the low audio problems are caused by improperly setting the AGC during alignment. A quick test is to shut off the AGC by pressing PRE/ATT and AGC together. If the volume comes shooting up the AGC is set wrong and is way too aggressive. Gregg R. Lengling, W9DHI, Retired Administrator http://www.milwaukeehdtv.org K2/100 S#3075 KX1 S# 57 Member: ARRL, RSGB, RCA, WERA and ORC -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Douglas Westover Sent: Sunday, October 10, 2004 12:41 PM To: [hidden email]; john Subject: Re: [Elecraft] Audio levels in K2 I use a pair of Sony 32 ohm phones and have plenty of audio out of the K2. 73, Doug W6JD ----- Original Message ----- From: "john" <[hidden email]> To: <[hidden email]> Sent: Sunday, October 10, 2004 4:01 AM Subject: [Elecraft] Audio levels in K2 > Hello All, > > I was chasing DX on the low end of 10m yesterday (good paths to VK!) > and noted that even with phones on, I had the AF gain all the way up...and > could > use more. > > Perhaps this was due to the headphones I was using, but I wonder if others > have noted the same thing. I think this is the only rig I've got that does > not have enough AF gain to blast me out of the phones. > > On vy strong sigs, I don't need the gain, but on the very weak ones, > I could use more. > > Thanks for your insight > John K5MO > ---------------------------------------------------------------------------- ---- > > --- > > Checked by AVG anti-virus system (http://www.grisoft.com). > Version: 6.0.727 / Virus Database: 482 - Release Date: 7/26/04 > ---------------------------------------------------------------------------- ---- > _______________________________________________ > 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 _______________________________________________ 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 _______________________________________________ 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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AGC setting is probably the most often discovered internal problem with K2
audio. I believe that there is still an internal gremlin yet to be exorcised, based upon reports that Ihave heard over the years. However, one additional problem that helped me was changing to a pair of headphones that better matched the internal impedence of the K2. I believe that this is 32 ohms. Good luck, Fran _______________________________________________ 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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Make sure that L34 is set properly before you set the AGC. There could be a
lot of unwanted (unreceived) noise masking a proper AGC setting difficult or incorrect. I accidentally discovered the following technique while playing with Spectrogram. It is easy and it made a big difference in receive signal and MDS. I had meant to put this hint on the reflector long ago and keep forgetting. -------- How to best adjust L34 - "I.F. Amplifier Alignment" in the section of "Alignment and Test Part II," using Spectrogram. Follow the instructions for "I.F. Amplifier Alignment." When you get to the last step plug the PC sound card into the Speaker Jack (not Headphone as it attenuates some high frequencies). Viewing the display with either Spectrogram (or equivalent) or even DigiPan (or equivalent - Waterfall works best), you will notice some noise spread across the spectrum displayed. Make sure the XFIL is set for FL-1 OP-1. Now continue to adjust L34 for a compromise of the lowest displayed noise and the highest level of the tone. You will find a point where the noise is almost non existent. You may need to turn up the volume as you get close to a null. After making this adjustment, reset (align) the AGC. Even though I had adjusted this to what I thought was the best by "ear," after using this method and then re-adjusting the ARC threshold. I was amazed at the difference in sensitivity and audio level. I believe this is one of the problems/reasons some people complain about "low output volume." Rich, KE0X _______________________________________________ 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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In reply to this post by john-477
In a message dated 10/10/04 1:44:22 PM Eastern Daylight Time,
[hidden email] writes: > We've been over this topic many times. If you go thru the reflector > archives you find that most of the low audio problems are caused by > improperly setting the AGC during alignment. A quick test is to shut off > the AGC by pressing PRE/ATT and AGC together. If the volume comes shooting > up the AGC is set wrong and is way too aggressive. > Agreed! But some of us have experienced apparently low overall gain (not low audio) even with the AGC off. 73 de Jim, N2EY _______________________________________________ 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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In reply to this post by john-477
There is an alternative way to increase the K2 audio output to headphones.
The K2 RF board contains series 82 ohm resistors at R35 and R36 to reduce the volume for more sensitive headphones. If you have low impedance or insensitive headphones, the value of these two resistors can be reduced to give you more audio output. There is an easy way to check if this will help. Plug your headphones into the K2 external speaker jack on the rear panel. If you now have plenty of volume from the headphones, reducing the values of R35 and R36 will fix the problem. -John KI6WX ----- Original Message ----- From: "john" <[hidden email]> > Hello All, > > I was chasing DX on the low end of 10m yesterday (good paths to VK!) > and noted that even with phones on, I had the AF gain all the way up...and > could > use more. > > Perhaps this was due to the headphones I was using, but I wonder if others > have noted the same thing. I think this is the only rig I've got that does > not have enough AF gain to blast me out of the phones. > > On vy strong sigs, I don't need the gain, but on the very weak ones, > I could use more. > > Thanks for your insight > John K5MO _______________________________________________ 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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In reply to this post by n6wg
One option for more volume would be to change the LM380 audio amp to an LM386. There are only 3 pins in common, but 3 others are just offset one hole and could be easily done by hand. Add a 10 uF cap across the remaining two pins, and you've got 12 db more gain than the original. You might even save a couple of mA, since the quiescent drain is lower.
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In reply to this post by N2EY
----- Original Message ----- > > But some of us have experienced apparently low overall gain (not low > audio) > even with the AGC off. > Jim and all, For older K2s, I have seen one report that changing the winding of T7 from the old 11:3 turns to the newer 20:5 turns allows one to pick up an additional 3 dB gain. I haven't tried it yet on my Field Test SN00020, so I cannot speak from personal experience. The newer turns ratio was in K2 manual rev C, but the Field Test and Rev A manuals used the older turns ratio - other than that I don't know when the cutover was made. If you have an older K2 with the 11:3 turns ratio, you might want to give it a try and let the rest of us know the results. 73, Don W3FPR _______________________________________________ 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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