Mic Gain, K2/100
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I was finally able to get my K2 (#0061) upgraded to a K2/100 just prior to
CQWW this past weekend. The KPA100 was bought in 2004 and sat on a shelf for a year or two. Anyway, I was doing some A/B checks after completing and testing the unit, while trying to call some stations on 20 meters. I compared a Yeasu FT-890 to the K2/100. I noticed there were a few stations that I called and called on the K2, that were then workable in one or two calls after switching over to the FT-890. I did some power checks, and found that in CW mode, the K2 was the same, if not slightly more power (reading on the same meter, same antenna, using an A/B switch) But on SSB, the voice peaks of the K2 are 25-30% lower than those of the FT-890. I am using dynamic mikes on both radios... on the K2 it's a Yaesu MH-31 Mic. I also used this mic on both radios and noted voice power peaks almost twice that of the K2 (70 w vs 40w). My K2 is set for SSBA of 3, and SSBC of 3-1. My KSB2 firmware is 1.07 I have seen a few references to mods on the KSB2, including swapping resistors to increase mic gain. I have also seen references that they should not be done on K2/100 units. Are there any internal mic gain mods that can be used on the KSB2 in a K2/100? Is there anything else I can do short of the external mic amp? I also notice that sometimes I get full power on the first "letter", sometimes it starts lower on "whiskey 1" and bumps up on "papa alpha" -- anyone else seen this on the K2/100? Bill W1PA (K2 FT #61) _______________________________________________ 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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Bill,
The Yaesu MH31 mic will normally drive the K2 to full output with no problem. I really cannot coment on the difference between your Yaesu and the K2 power out as indicated on your meter - I do not know how your particular meter responds, but I know you have a mic gain control on the Yaesu front panel, and it can be easily overdriven giving the appearance of greater power output. The K2 LED will indicate the peak output power in most cases. For any particular power setting, switch to CW and key the K2 while observing the LED meter (in RF mode of course) to see how many LEDs are illuminated. Then switch to SSB - if the peaks go up to the same point as you saw in the CW test, you are driving the K2 to full PEP output. If you want more average power, increase the compression setting. 73, Don W3FPR > -----Original Message----- > > I was finally able to get my K2 (#0061) upgraded to a K2/100 just > prior to > CQWW this past weekend. The KPA100 was bought in 2004 and sat on > a shelf for > a year or two. > > Anyway, I was doing some A/B checks after completing and testing > the unit, > while trying to call some stations on 20 meters. > > I compared a Yeasu FT-890 to the K2/100. > I noticed there were a few stations that I called and called on > the K2, that > were then workable in one or two calls after switching over to > the FT-890. I > did some power checks, and found that in CW mode, the K2 was the same, if > not slightly more power (reading on the same meter, same antenna, > using an > A/B switch) > > But on SSB, the voice peaks of the K2 are 25-30% lower than those of the > FT-890. I am using dynamic mikes on both radios... on the K2 > it's a Yaesu > MH-31 Mic. I also used this mic on both radios and noted voice > power peaks > almost twice that of the K2 (70 w vs 40w). My K2 is set for SSBA > of 3, and > SSBC of 3-1. My KSB2 firmware is 1.07 > > I have seen a few references to mods on the KSB2, including swapping > resistors to increase mic gain. I have also seen references that > they should > not be done on K2/100 units. > > Are there any internal mic gain mods that can be used on the KSB2 in a > K2/100? Is there anything else I can do short of the external mic amp? > > I also notice that sometimes I get full power on the first "letter", > sometimes it starts lower on "whiskey 1" and bumps up on "papa > alpha" -- > anyone else seen this on the K2/100? > > Bill > W1PA (K2 FT #61) > _______________________________________________ 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 Bill Acito W1PA
There were some mods that changed the gain distribution within the K2 RF and
audio paths that some suggested could increase the IMD. I suspect that's where the comments about not doing them on a KPA100 came from, although it's hard to see how an S-9 signal running 5 watts is any less sensitive to IMD issues than an S-9 signal running 100 watts <G>. One change you can make that only increases the input from the mic and doesn't affect the gain distribution within the K2 is to increase the value of R14 on the KSB2 module. The "stock" value is 1K. Raising it to 5K or more has helped a lot of rigs make full output from an existing mic without extra help. Since it's at the microphone input it has the same effect as using a slightly "hotter" microphone. Don mentioned a mic that should work. In general it seems that dynamic mics are more likely to have marginal output for driving the K2 to full output. I originally used a dynamic mic on my K2/100 and switched to an electret element that had considerably more output. The bargraph on the K2 is will show you the peak output. Since the RF output on SSB is a function of audio and RF levels, and the RF gain in the transmitter is lowest on 10 meters, that's a good band to check if you want to be sure you have full output on all bands with a given mic. Be sure to set the compression level to where you want it before checking. Higher compression levels require a little more audio from the mic. On voice peaks the last bar on the bargraph should just flicker at times in RF mode. A better way is to switch to ALC mode on the bargraph. The bargraph reads backwards in ALC mode to remind you that you're not in RF mode. If the right-most bar flickers on voice peaks running 100 watts, you are getting all the output you can use. The flickering bar indicates that the K2 is turning down the gain to hold the RF level to 100 watts. As you reduce the power level below 100 watts, you'll see more bars light up on peaks, indicating that the ALC is turning the gain down more and more to hold the output to the requested power. As long as one bar flickers, more audio gain won't make your signal any louder. About the level changing after the first syllable, you'll see the same thing on CW mode too sending the first dit or dah. That's a function of how the power control works. The POWER knob sets a requested power level. When you transmit the K2 senses the actual output power and the ALC circuit then adjusts the RF gain in the transmitter to provide the requested power. It may take a moment for this to happen, so you'll often see a higher or lower power on the first syllable (or code element in CW) until the ALC circuit has time to react. Ron AC7AC _______________________________________________ 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 |
Re: Mic Gain, K2/100
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Ron AC7AC wrote:
There were some mods that changed the gain distribution within the K2 RF and audio paths that some suggested could increase the IMD. I suspect that's where the comments about not doing them on a KPA100 came from, although it's hard to see how an S-9 signal running 5 watts is any less sensitive to IMD issues than an S-9 signal running 100 watts <G>. ------------------------------------------------------------------------- Perhaps the comments about not doing them when a KPA100 is used were based on the fact that the level of IMD products at the output from the cascade of a K2 and KPA100 could increase quite 'rapidly' as the level of IMD products from the K2 increased. Two reasons being that the KPA100 exhibits gain and is itself not perfectly linear. So the level of the IMD products around a S-9 signal from the K2/100 could be greater than those around the S-9 signal from the K2. A similar situation occurs in a receiver where a 'weak' IF or IF branch amplifier can ruin the performance of the overall receiver even if it has a 'strong' front end. 73, Geoff GM4ESD _______________________________________________ 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 Ron D'Eau Claire-2
I should also mention that I am getting ALC indication at full power (one
LED bar only). So next question... anyone recommend electret-based mic's (since the Elecraft hand version is no longer available)? (I'd like to try that first before additonal mods) I have a wealth of Ten Tec equipment... one of theirs? There is also a mod'd mic sold for the FT100 (adds a pre-amp). Anyone have a electret-based mic they are haiving good success with? Bill W1PA K2/100 #61 _______________________________________________ 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 Bill Acito W1PA
Bill et al,
A few years ago Bob Hightower, NK7M,s old a mic preamp kit designed . The printed circuit board was small and fit inside the K2 or some microphones. I got one and have had good results from it. I use the Kenwood stock hand microphone for the TS-850S. I picked the mic up on ebay for $20. The links to Bob's preamp kit are not valid. Maybe someone else knows how to reach Bob. Mark, KJ7BS Glendale, AZ ---- Bill Acito <[hidden email]> wrote: ============= I was finally able to get my K2 (#0061) upgraded to a K2/100 just prior to CQWW this past weekend. The KPA100 was bought in 2004 and sat on a shelf for a year or two. Anyway, I was doing some A/B checks after completing and testing the unit, while trying to call some stations on 20 meters. I compared a Yeasu FT-890 to the K2/100. I noticed there were a few stations that I called and called on the K2, that were then workable in one or two calls after switching over to the FT-890. I did some power checks, and found that in CW mode, the K2 was the same, if not slightly more power (reading on the same meter, same antenna, using an A/B switch) But on SSB, the voice peaks of the K2 are 25-30% lower than those of the FT-890. I am using dynamic mikes on both radios... on the K2 it's a Yaesu MH-31 Mic. I also used this mic on both radios and noted voice power peaks almost twice that of the K2 (70 w vs 40w). My K2 is set for SSBA of 3, and SSBC of 3-1. My KSB2 firmware is 1.07 I have seen a few references to mods on the KSB2, including swapping resistors to increase mic gain. I have also seen references that they should not be done on K2/100 units. Are there any internal mic gain mods that can be used on the KSB2 in a K2/100? Is there anything else I can do short of the external mic amp? I also notice that sometimes I get full power on the first "letter", sometimes it starts lower on "whiskey 1" and bumps up on "papa alpha" -- anyone else seen this on the K2/100? Bill W1PA (K2 FT #61) _______________________________________________ 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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Just remember also that the OP1 filter for SSB receive is also used on
transmit. I found that my Heil Pro headset was too muddy so I tailored the OP1 filter for best response and have got fantastic audio reports on my K2. Gregg R. Lengling, W9DHI, Retired,Again K2/100 SN 3075 http://www.milwaukeehdtv.org http://forums.ham-radio.ch/ ----- Original Message ----- From: "Mark Saunders, KJ7BS" <[hidden email]> To: <[hidden email]>; "Bill Acito" <[hidden email]> Sent: Monday, October 30, 2006 3:03 PM Subject: Re: [Elecraft] Mic Gain, K2/100 > Bill et al, > > A few years ago Bob Hightower, NK7M,s old a mic preamp kit designed . The > printed circuit board was small and fit inside the K2 or some microphones. > I got one and have had good results from it. I use the Kenwood stock hand > microphone for the TS-850S. I picked the mic up on ebay for $20. > > The links to Bob's preamp kit are not valid. Maybe someone else knows how > to reach Bob. > > Mark, KJ7BS > Glendale, AZ > > ---- Bill Acito <[hidden email]> wrote: > > ============= > I was finally able to get my K2 (#0061) upgraded to a K2/100 just prior to > CQWW this past weekend. The KPA100 was bought in 2004 and sat on a shelf > for > a year or two. > > Anyway, I was doing some A/B checks after completing and testing the unit, > while trying to call some stations on 20 meters. > > I compared a Yeasu FT-890 to the K2/100. > I noticed there were a few stations that I called and called on the K2, > that > were then workable in one or two calls after switching over to the FT-890. > I > did some power checks, and found that in CW mode, the K2 was the same, if > not slightly more power (reading on the same meter, same antenna, using an > A/B switch) > > But on SSB, the voice peaks of the K2 are 25-30% lower than those of the > FT-890. I am using dynamic mikes on both radios... on the K2 it's a Yaesu > MH-31 Mic. I also used this mic on both radios and noted voice power peaks > almost twice that of the K2 (70 w vs 40w). My K2 is set for SSBA of 3, and > SSBC of 3-1. My KSB2 firmware is 1.07 > > I have seen a few references to mods on the KSB2, including swapping > resistors to increase mic gain. I have also seen references that they > should > not be done on K2/100 units. > > Are there any internal mic gain mods that can be used on the KSB2 in a > K2/100? Is there anything else I can do short of the external mic amp? > > I also notice that sometimes I get full power on the first "letter", > sometimes it starts lower on "whiskey 1" and bumps up on "papa alpha" -- > anyone else seen this on the K2/100? > > Bill > W1PA (K2 FT #61) > > > _______________________________________________ > 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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Good point, Gregg!
I have the FL1 BFO frequency on my K2 set for optimum transmit audio (using the OPT1 filter of course). For my taste the receive audio is a bit "bright" on many signals (not enough low frequency response) so I have the FL2 position BFO frequency set up to shift the passband for a more pleasing response. Since the K2 uses only the OPT1/FL1 settings for transmit, setting up the other filter positions for different audio characteristics has no effect on the transmit audio, even if one is selected for receive when I transmit. Ron AC7AC -----Original Message----- Just remember also that the OP1 filter for SSB receive is also used on transmit. I found that my Heil Pro headset was too muddy so I tailored the OP1 filter for best response and have got fantastic audio reports on my K2. Gregg R. Lengling, W9DHI, Retired,Again K2/100 SN 3075 http://www.milwaukeehdtv.org http://forums.ham-radio.ch/ _______________________________________________ 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 Gregg R. Lengling
As an experiment, I'm going to try the KSB2 R14 mod (change value to something 5k to 10k). I have a couple of other irons in the fire that I will look at as well, but this one was quick and I had the parts. What negative effects should I watch for? I have a 100Mhz scope... anything I should be looking at with that? Bill W1PA K2/100 #61 _______________________________________________ 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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There's nothing to look for. All you're doing by increasing the value of R14
is increasing the amount of audio from the mic reaching the audio (speech compressor) chip. It has the same effect as screaming into your mic, without all the noise or getting yourself hoarse <G>. Now, there is a *different* mod that apparently can have bad side effects by over-driving the balanced modulator at the output of the audio chip. That was to swap resistor R14 and R2. R2 is a 5.6 k resistor in the audio line between the speech compressor and the balanced modulator. Replacing it with the 1K from R14 helped increase the gain even more by increasing the drive to the balanced modulator. However, it was suggested that doing so might over-drive the balanced modulator. Ron AC7AC -----Original Message----- As an experiment, I'm going to try the KSB2 R14 mod (change value to something 5k to 10k). I have a couple of other irons in the fire that I will look at as well, but this one was quick and I had the parts. What negative effects should I watch for? I have a 100Mhz scope... anything I should be looking at with that? Bill W1PA K2/100 #61 _______________________________________________ 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 Bill Acito W1PA
I have been using a Kenwood MC80 with my K2. I use batteries, but I have
been told that the mic. will power with 5 volts. The mic. does have a gain/level control that can be used to dial in the right level. Richard Kent WD8AJG K2 5296 Bill wrote, I should also mention that I am getting ALC indication at full power (one LED bar only). So next question... anyone recommend electret-based mic's (since the Elecraft hand version is no longer available)? (I'd like to try that first before additonal mods) I have a wealth of Ten Tec equipment... one of theirs? There is also a mod'd mic sold for the FT100 (adds a pre-amp). Anyone have a electret-based mic they are haiving good success with? Bill W1PA K2/100 #61 _______________________________________________ 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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