++++++++++++++++++ Also known as the LSB/USB Recieve Pitch Equalization Mod ++++++++++++++++++ Date: Thu, 11 Jul 2002 22:41:30 -0700 From: "John Grebenkemper, KI6WX" To: Elecraft Mailing List Subject: [Elecraft] Mods To The KSB2 For the last 6 months I have worked on a set of changes to the KSB2 that provide increased SSB performance for the K2. These changes are not required for the K2 to function well in the SSB mode, but are intended for those who wish to obtain the best possible performance. There are four major changes discussed in the document. The first allows the builder to select different SSB bandwidths for the KSB2 filter. This may be especially useful if you desire a wider SSB filter. The second improves the flatness of the 2nd Xtal Filter. I had posted this change to the reflector a few months ago and several people have implemented it in their K2. The change makes the LSB and USB response in receive nearly identical. The third change increases the RF gain of the KSB2 so that it will function with lower output microphones without resorting to various resistor changes that have been tried by a number of people. It also allows the K2 to achieve a slightly higher SSB output on 10 meters. The fourth change reduces the in-band audio intermodulation distortion that occurs in the KSB2 modulator by 15-20 dB. This change is most important for data modes, but should also increase the audio fidelity of the KSB2 in SSB transmissions. All of these changes are described in a document "Improving the Performance of the KSB2" which may be downloaded from my website at http://home.pacbell.net/johngreb/KI6WX.html -John KI6WX +++++++++++++++++++ Date: Sun, 14 Jul 2002 15:26:09 -0500 To: "Jeff Burns" , "elecraft_list" From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] KI6WX modes for the KSB2 ? Jeff: >First the simple one. I have a whole box of parts marked "2N2222". Are these >equivalent to the PN2222? If not, what is the difference? It would be nice >to know for future reference. As far as I know, the 2N2222 is(was) generally a matal-cased device, with the PN2222 being the plastic equivalnet. However, I can recall when BOTH case types were labeled 2N2222. The devices are only used for switching, not in a linear mode, so either can be used, AS LONG AS, if the metal cased version is used, the case is INSULATED from shorting out to ANYTHING. >Now the more difficult question. I have a Heil HC4 microphone element, and >changed R2 to get more drive. Everything works now, including VOX, but I >suspect that a little more drive would be beneficial. > >As I read John's notes the "KSB2 Increased Gain Modification" is appropriate >for my microphone, but I should leave R2 as I have it and skip the "KSB2 >Reduced Intermodulation Distortion Modification." Is this correct? Would it >be better to do the "KSB2 Reduced Intermodulation Distortion Modification" >and add a pre-amp to my microphone if the drive is insufficient? I have had >the parts for a pre-amp in an envelope for almost 2 years. From my field testing of John's mod before it was completely written up, I RETURNED my R2 back to 5.6k AND I changed R14 BACK to 1K. The changing of R2 (back to 5.6K) was suggested quite a while ago. Seems reducing it to 1K tended to overdrive U5. With R2 and R14 returned to 'stock', and with the mod installed, using a Heil HC5 element, I can now run my SSB A at about 2 with no problem and apparent full output. I don't think you'll require a preamp after this mod's been installed. 73, Tom Hammond N0SS ++++++++++++++++++++ Date: Sun, 14 Jul 2002 13:29:21 -0700 From: "John Grebenkemper, KI6WX" Subject: Re: [Elecraft] KI6WX modes for the KSB2 ? To: Elecraft Mailing List Jeff; > I have been reading over KI6WX modes for the KSB2 and have a few questions > before I jump in. > > First the simple one. I have a whole box of parts marked "2N2222". Are these > equivalent to the PN2222? If not, what is the difference? It would be nice > to know for future reference. The PN2222 is a plastic case version of the 2N2222. I'd be a little reluctant to use the metal case version because the collector is tied to the metal case and might short to a nearby part. The PN2222A/2N2222A has slightly better breakdown voltages and can be used as a substitute. I believe Radio Shack still carries the PN2222. > > Now the more difficult question. I have a Heil HC4 microphone element, and > changed R2 to get more drive. Everything works now, including VOX, but I > suspect that a little more drive would be beneficial. > > As I read John's notes the "KSB2 Increased Gain Modification" is appropriate > for my microphone, but I should leave R2 as I have it and skip the "KSB2 > Reduced Intermodulation Distortion Modification." Is this correct? Would it > be better to do the "KSB2 Reduced Intermodulation Distortion Modification" > and add a pre-amp to my microphone if the drive is insufficient? I have had > the parts for a pre-amp in an envelope for almost 2 years. This is a more difficult question to answer. Reducing R2 increases the audio gain of the KSB2, but makes it more likely you will drive the NE602 input into clipping, especially if you set SSBC greater than 1-1. With a low gain microphone, I would do the following. Add the increased gain mod and put the 2.2K resistor across R1 (this resistor reduces your dependency on the input impedance of the NE602 to set the audio gain). If there isn't enough audio gain to get to a full 10 watts on 10 meters in SSBC 1-1, I would then decrease R2 until I can get enough output. I wouldn't reduce R2 below 2K unless you avoid running SSBC above 1-1; audio compression will create really strong audio clipping with compression enabled at this audio gain level. An audio preamp on the mic input would be even a better solution. -John KI6WX > > > > Jeff Burns > > AD9T +++++++++++++++++ Date: Sun, 14 Jul 2002 21:24:54 -0400 From: "Mark J. Dulcey" To: Jeff Burns Cc: elecraft_list Subject: Re: [Elecraft] KI6WX modes for the KSB2 ? Jeff Burns wrote: > First the simple one. I have a whole box of parts marked "2N2222". Are these > equivalent to the PN2222? If not, what is the difference? It would be nice > to know for future reference. The 2N2222 is a general-purpose NPN transistor in a metal can. The PN2222 and MPS2222 are similar transistors in a plastic TO-92 package; similar characteristics, but less power dissipation because of the higher thermal resistance of the plastic package. The metal-can transistors are better for high-power applications, such as the QRP transmitters where they are used as final output stages. On the other hand, the plastic-body parts are better when you're going to install them in a place where the metal can could cause a short circuit. For example, a metal-can 2N2222 would not be suitable for the 2nd XFIL mod for the K2, and I don't think it would work for the KI6WX mod for the KSB2 for the same reason. > As I read John's notes the "KSB2 Increased Gain Modification" is appropriate > for my microphone, but I should leave R2 as I have it and skip the "KSB2 > Reduced Intermodulation Distortion Modification." Is this correct? Would it > be better to do the "KSB2 Reduced Intermodulation Distortion Modification" > and add a pre-amp to my microphone if the drive is insufficient? I have had > the parts for a pre-amp in an envelope for almost 2 years. My reading is different. As I understand it, the reduced IMD mod is ALWAYS a good idea, as it will improve the spectral purity of your signal. You then may also need the increased gain mod, depending on the microphone you plan to use. Adding the preamp to your microphone would be a reasonable alternative to the increased gain mod. +++++++++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: , Subject: RE: [Elecraft] KSB2 Increased Gain Mod Date: Tue, 23 Jul 2002 08:14:54 -0700 ... When tuning up my K2/100 puts out 100 watts on 12 and 10 meters; but if my Bird 43 wattmeter movement in SSB is any indication, the KSB2 needs a little help on these higher frequencies. ... Roy Morris W4WFB The K2's rf output metering measures the peak power. When you talk, the bar graph should flash over to the right hand bar on SOME voice peaks with the POWER control turned up, indicating either 10 or 100 watts PEP. Also, in ALC mode (press and hold Display button), you should see at least one bar flash on some peaks. In "ALC" remember the bargraph reads right to left to remind you that you are looking at the ALC action. If you are getting at least one bar of ALC to flash on occasionally, more gain won't help. That ALC bar is indicating that the K2's control circuit t is turning down the gain to hold the output level down to what you set the POWER control for. The amount of "wiggle" on an average reading meter will depend a great deal on the characteristics of your voice AND on the level of compression you have set. The least amount of wiggle will be with the compression off (SSbC at 1-1). Increasing SSbC to 1-2, 1-3, or 1-4 will show more wiggle as the compression increases the average to peak ratio of your voice waveform, and your audio will start to sound less 'natural' on the air as well. If your audio gain is definitely low, be sure you do NOT have the audio attenuator turned on (SSBA 1). SSBA 2 or 3 turns the attenuator off. Ron AC7AC K2 # 1289 +++++++++++++++++++ From: "Don Brown" To: "Harry Yingst" , "Elecraft_Reflector" Subject: Re: [Elecraft] LSB/USB Recieve Pitch Equalization Mod Date: Wed, 21 May 2003 13:05:28 -0500 Hi This mod is not needed if the SN is greater than 3000. The parts are not in the SSB kit but are available on the mod kit order page for radios with SN less than 3000. The parts are 2n3904 or 2n2222, 3.9k, 5.6k, .01uf, 100pf. Instructions are on the Elecraft web site. Don Brown KD5NDB ----- Original Message ----- From: "Harry Yingst" To: "Elecraft_Reflector" Sent: Wednesday, May 21, 2003 12:44 PM Subject: [Elecraft] LSB/USB Recieve Pitch Equalization Mod > I was reading The Errata sheet for the SSB Option. > > It States "we strongly recommend making this modification, which > involves only a few added parts." (In reference to the LSB/USB Receive > Pitch Equalization Mod). > > Are the required parts for this mod included in the SSB Option Kit? > > > ===== > Harry - AB2PN +++++++++++++++++++