Re: [Drakelist] Looking for an AC-4
ph...@aol.com writes: Looking for a Drake AC-4 power supply in good shape, must be complete & functional even if not re-habbed/re-capped/upgraded. Just need the supply, Paul, K4MSG I have one, intact, original, and functional, will even sell the Heathkit recap package which is not installed. Unit number is 44606. Carl wd8nhk ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] D-104 microphone wiring question
I'm trying to wire a D-104 Silver Eagle to my T4XB and not having much luck. There's 5 wires from the mike: White w/Shield, Black, Red, Blue and Yellow. I believe the correct wiring to the S230 would be: Red to tip, White to middle (audio) and Black and Shield to ground? Any suggestions would be welcome. Thanks! ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-7 Oscillating?
Gents, My TR-7 started doing something unusual this morning. I tried to check into a 40m phone net and I noticed my external VSWR meter going crazy. It's a dual-needle type and I would start talking and things would be okay and then the reflected needle would instantly jump to infinity. Unkey and try again and it would do the same...normal for a second or two and then a jump to infinity. I think I saw the same behavior when I first got this radio and did the full alignment when adjusting the two big power output pots and it went into oscillation. (I don't recall the exact names of those pots but I recall one was in the PA section and one underneath the radio.) My radio seemed to be a little touchy to those adjustments and wanted to oscillate but all has been well for the last 18 months or so until this morning. As luck would have it, I recently rebuilt my microphone cable, re-arranged my ham desk, and adjusted my antenna slightly so I've touched about everything but I can't find any evidence that I have any kind of flaky connection in the antenna as that was my first thought given the reflected power indication. The problem is that the reflected needle just goes from zero to infinity and I think that's exactly what it did when it went into oscillation. My VSWR meter uses an inline directional coupler arrangement (Palstar WM-150)on the input to the tuner. The receive strength is rock solid and we have no wind whatsoever on the antenna today. I tried reducing mic gain and so on but the problem still happens. It doesn't necessarily make sense to me that oscillating would cause the VSWR needle to jump but I'm pretty sure this is what it did when I adjusted those pots about 2 years ago. Thought I would check with the experts before dragging it out of the operating position and trying to adjust those pots. Thanks... Dave K8JDC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 Oscillating?
Dave, Does the built-in TR-7 reflected power meter jump to infinity? A couple troubleshooting suggestions: Disconnect the antenna and feed the TR-7 directly into a dummy load. Disconnect the mic and see if this happens on CW. Good luck with it. Tom, AG9X On Sat, Oct 16, 2010 at 9:19 AM, K8JDC wrote: > Gents, > > My TR-7 started doing something unusual this morning. I tried to check > into a 40m phone net and I noticed my external VSWR meter going crazy. It's > a dual-needle type and I would start talking and things would be okay and > then the reflected needle would instantly jump to infinity. Unkey and try > again and it would do the same...normal for a second or two and then a jump > to infinity. I think I saw the same behavior when I first got this radio > and did the full alignment when adjusting the two big power output pots and > it went into oscillation. (I don't recall the exact names of those pots but > I recall one was in the PA section and one underneath the radio.) My radio > seemed to be a little touchy to those adjustments and wanted to oscillate > but all has been well for the last 18 months or so until this morning. As > luck would have it, I recently rebuilt my microphone cable, re-arranged my > ham desk, and adjusted my antenna slightly so I've touched about everything > but I can't find any evidence that I have any kind of flaky connection in > the antenna as that was my first thought given the reflected power > indication. The problem is that the reflected needle just goes from zero to > infinity and I think that's exactly what it did when it went into > oscillation. My VSWR meter uses an inline directional coupler arrangement > (Palstar WM-150)on the input to the tuner. The receive strength is rock > solid and we have no wind whatsoever on the antenna today. I tried reducing > mic gain and so on but the problem still happens. It doesn't necessarily > make sense to me that oscillating would cause the VSWR needle to jump but > I'm pretty sure this is what it did when I adjusted those pots about 2 years > ago. Thought I would check with the experts before dragging it out of the > operating position and trying to adjust those pots. > > Thanks... > > Dave > K8JDC > > ___ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-7 - More Info
Some more data points: 1. I cannot get the radio to malfunction on a dummy load. I have only seen the problem on 40m when connected to the antenna which is a 135-ft doublet fed with ladder line. Tuner is a Tentec 238B and the tuner is right next to the TR-7. That leads me to wonder if there's some RF from the balanced line that is part of the problem. 2. I checked on 20m and don't see the problem on either a dummy load or my antenna which is a Steppir. Output power is stable. 3. The TR-7 forward meter goes to zero when the problem happens. Reflected indicator goes max scale. So those readings are the same as my external meter. 4. I hooked up my Tentec Orion to the same tuner/antenna and all is well. No hint of anything wrong with the antenna. Output power is totally stable. 5. This problem happens on CW as well as SSB. I have a toggle switch wired to key the radio for tuning and it will put out full power into the antenna for a few seconds and then the reflected power will go to infinity. Power into the dummy load is fine. 6. I did notice at least once that the problem occurred just as I unkeyed in CW mode. So, just as I unkeyed, I saw the reflected power jump high. So, the above leads me to wonder about the transmit relay. I wondered if the contacts are somehow dirty but I don't see the problem on the dummy load so that leads me to wonder if the T/R relay is somehow being affected by some RF from the ladder line which is nearby. It's not easily possible to separate the radio and tuner any more because of how my desk is laid out. The ladder line comes out of the tuner and goes to the left to the outside world. The TR-7 sits just to the right of the tuner so the ladder line does not go behind the radio although it's only about 10 inches away from the T/R relay when it exits the tuner. ?? Dave K8JDC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
Dave, Do you have a good ground on your balanced line tuner?? I have those problems with my tuners and ladder line if I don't have a good ground hooked up. 73, Don, WB5HAK ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
Also check for a broken lead somewhere in the ladder line as well as the connections at the antenna. The breaks can be hard to see sometimes, so you have to check very closely. I have basically the same set-up with one of my TR7s but I use an MN75. When one of the leads breaks on the ladder line, depending on where it is located, it can cause strange indications in the shack due to RF radiation. Steve w7jsc - Original Message - From: "Don Cunningham" To: "K8JDC" ; Sent: Saturday, October 16, 2010 10:10 AM Subject: Re: [Drakelist] TR-7 - More Info > Dave, > Do you have a good ground on your balanced line tuner?? I have those > problems with my tuners and ladder line if I don't have a good ground > hooked > up. > 73, > Don, WB5HAK > > > ___ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
Dave - If the external SWR meter goes to 'infinity' on reflected, then the problem is PAST that meter. The fact that it is ok on a dummy load also indicates an antenna problem. Sounds like an open feedline, - OR - balun, if used. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-B, C-Line& TR-4/C Service Supplement CDs K8JDC wrote: Some more data points: 1. I cannot get the radio to malfunction on a dummy load. I have only seen the problem on 40m when connected to the antenna which is a 135-ft doublet fed with ladder line. Tuner is a Tentec 238B and the tuner is right next to the TR-7. That leads me to wonder if there's some RF from the balanced line that is part of the problem. 2. I checked on 20m and don't see the problem on either a dummy load or my antenna which is a Steppir. Output power is stable. 3. The TR-7 forward meter goes to zero when the problem happens. Reflected indicator goes max scale. So those readings are the same as my external meter. 4. I hooked up my Tentec Orion to the same tuner/antenna and all is well. No hint of anything wrong with the antenna. Output power is totally stable. 5. This problem happens on CW as well as SSB. I have a toggle switch wired to key the radio for tuning and it will put out full power into the antenna for a few seconds and then the reflected power will go to infinity. Power into the dummy load is fine. 6. I did notice at least once that the problem occurred just as I unkeyed in CW mode. So, just as I unkeyed, I saw the reflected power jump high. So, the above leads me to wonder about the transmit relay. I wondered if the contacts are somehow dirty but I don't see the problem on the dummy load so that leads me to wonder if the T/R relay is somehow being affected by some RF from the ladder line which is nearby. It's not easily possible to separate the radio and tuner any more because of how my desk is laid out. The ladder line comes out of the tuner and goes to the left to the outside world. The TR-7 sits just to the right of the tuner so the ladder line does not go behind the radio although it's only about 10 inches away from the T/R relay when it exits the tuner. ?? Dave K8JDC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake AC-4 - found one
Thanks for those who offered, I found one locally. Paul, K4MSG ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
That *almost* sounds like the 40 Meter oscillation problem - except for the behaviour of the forward power meter. Some TR-7s are prone to PA deck oscillation in the 40 meter band with a reactive load (antenna). The easy fix for this is to reduce the gain of the predriver board by adjusting the provided gain pot. The better fix that I have arrived at is to increase the negative feedback in the predriver circuit, which reduces the overall gain of the predriver and still allows full power output to be achieved. I've done this only on REV. 2 predrivers, I haven't had a REV. 1 come across my bench yet. 73 -Jim On Sat, 16 Oct 2010 13:00:30 -0400, Garey Barrell wrote: >Dave - > >If the external SWR meter goes to 'infinity' on reflected, then the >problem is PAST that meter. The fact that it is ok on a dummy load also >indicates an antenna problem. > >Sounds like an open feedline, - OR - balun, if used. > >73, Garey - K4OAH >Glen Allen, VA > >Drake 2-B, 2-C/2-NT, 4-B, C-Line& >TR-4/C Service Supplement CDs > > > >K8JDC wrote: >> Some more data points: >> >> 1. I cannot get the radio to malfunction on a dummy load. I have >> only seen the problem on 40m when connected to the antenna which is a >> 135-ft doublet fed with ladder line. Tuner is a Tentec 238B and the >> tuner is right next to the TR-7. That leads me to wonder if there's >> some RF from the balanced line that is part of the problem. >> >> 2. I checked on 20m and don't see the problem on either a dummy load >> or my antenna which is a Steppir. Output power is stable. >> >> 3. The TR-7 forward meter goes to zero when the problem happens. >> Reflected indicator goes max scale. So those readings are the same as >> my external meter. >> >> 4. I hooked up my Tentec Orion to the same tuner/antenna and all is >> well. No hint of anything wrong with the antenna. Output power is >> totally stable. >> >> 5. This problem happens on CW as well as SSB. I have a toggle switch >> wired to key the radio for tuning and it will put out full power into >> the antenna for a few seconds and then the reflected power will go to >> infinity. Power into the dummy load is fine. >> >> 6. I did notice at least once that the problem occurred just as I >> unkeyed in CW mode. So, just as I unkeyed, I saw the reflected power >> jump high. >> >> So, the above leads me to wonder about the transmit relay. I wondered >> if the contacts are somehow dirty but I don't see the problem on the >> dummy load so that leads me to wonder if the T/R relay is somehow >> being affected by some RF from the ladder line which is nearby. It's >> not easily possible to separate the radio and tuner any more because >> of how my desk is laid out. The ladder line comes out of the tuner >> and goes to the left to the outside world. The TR-7 sits just to the >> right of the tuner so the ladder line does not go behind the radio >> although it's only about 10 inches away from the T/R relay when it >> exits the tuner. >> >> ?? >> >> Dave >> K8JDC >> >> > >___ >Drakelist mailing list >Drakelist@zerobeat.net >http://mailman.zerobeat.net/mailman/listinfo/drakelist -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D-104 microphone wiring question
On Sat, 16 Oct 2010 09:54:20 -0400, Joe Loverti wrote: >I'm trying to wire a D-104 Silver Eagle to my T4XB and not having much luck. Joe, There is a plethora of D-104 informaion on the internet - schematics, wiring info, etc. Google is your friend. I could look it up for you later, as I really don't have the time right now, but it's out there for you to find. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] bad conditions ? - wasting my time
Has there been poor propagation last couple days, solar storm maybe ? I went to use the R4B yesterday, there was a prominent "buzzing" noise on the bands, and could hardly get any signals on any bands. Didn't sound like regular QRN, and I couldn't find any noise source in the garage, so I decided must be something punk in the R4B. So I got out the R4A and proceeded to do a tube swap (second step was going to be a voltage test). No diff. So I hooked up the R4A and was dumbfounded no signals either. So I put the tubes back the way there were before and was going to do the voltage check on the R4B today. So, I get it flipped over, turn it on, and lo and behold lots of great signals and no QRN. Sheesh. Chuck, K1OM ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] bad conditions ? - wasting my time
Chuck, Same problem here on 40m last night anyway. I was trying to get some audio checks on several mics and just gave up and used the best one I have (a NIB EV-664, ugly Army green, but new, hi) and no one complained that could hear me. Same buzzing sound here, and VERY loud, usually way over S9, wiping out all but the very strong signals. My 100w just wasn't cutting it, hi. Hope it clears soon. I was afraid we, China, or Russia were testing new over the horizon radars!!. 73, Don, WB5HAK___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
> Date: Sat, 16 Oct 2010 12:03:18 -0400 > From: K8JDC > To: drakelist@zerobeat.net > Subject: [Drakelist] TR-7 - More Info > Message-ID: <4cb9ccc6.7020...@sbcglobal.net> > Content-Type: text/plain; charset=ISO-8859-1; > format=flowed > > Some more data points: > > 1. I cannot get the radio to malfunction on a dummy > load. I have only > seen the problem on 40m when connected to the antenna which > is a 135-ft > doublet fed with ladder line. Tuner is a Tentec 238B > and the tuner is > right next to the TR-7. That leads me to wonder if > there's some RF from > the balanced line that is part of the problem. > > 2. I checked on 20m and don't see the problem on > either a dummy load or > my antenna which is a Steppir. Output power is > stable. > > 3. The TR-7 forward meter goes to zero when the > problem happens. > Reflected indicator goes max scale. So those readings > are the same as > my external meter. > > 4. I hooked up my Tentec Orion to the same > tuner/antenna and all is > well. No hint of anything wrong with the > antenna. Output power is > totally stable. > > 5. This problem happens on CW as well as SSB. I > have a toggle switch > wired to key the radio for tuning and it will put out full > power into > the antenna for a few seconds and then the reflected power > will go to > infinity. Power into the dummy load is fine. > > 6. I did notice at least once that the problem > occurred just as I > unkeyed in CW mode. So, just as I unkeyed, I saw the > reflected power > jump high. > > So, the above leads me to wonder about the transmit > relay. I wondered > if the contacts are somehow dirty but I don't see the > problem on the > dummy load so that leads me to wonder if the T/R relay is > somehow being > affected by some RF from the ladder line which is > nearby. It's not > easily possible to separate the radio and tuner any more > because of how > my desk is laid out. The ladder line comes out of the > tuner and goes to > the left to the outside world. The TR-7 sits just to > the right of the > tuner so the ladder line does not go behind the radio > although it's only > about 10 inches away from the T/R relay when it exits the > tuner. > > ?? > > Dave > K8JDC I've not found a 135 ft antenna feed with ladder line to be ideal on 40 meters. It presents a high impedance/high RF voltage load to your tuner, increasing the RF field around the ladder line and probably causing RF feedback within your TR7. I'd attempt to lengthen the ladder line to find a combo that works better or better yet simply use another antenna on 40 mtrs. If you have enough room for 135 ft, you have enough room for a 66 ft coax feed dipole for 40. 73, Doug/WA1TUT ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
Jim - Is that a possibility? If the antenna is tuned to 20M by the tuner, and the transmitter is putting out 40M RF, then the transmitter is seeing a mismatch and 'shuts down'. Does it 'really' go to ZERO power or is it just rolled back to 20 or so Watts? BUT, if you put 40M RF into a tuner set for 20M why would the external power meter show high reflected power? Unless enough 40M RF is getting through the tuner to see the mismatched antenna My head hurts Worth looking into. What's the serial number of the transceiver?? 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-B, C-Line& TR-4/C Service Supplement CDs Jim Shorney wrote: That *almost* sounds like the 40 Meter oscillation problem - except for the behaviour of the forward power meter. Some TR-7s are prone to PA deck oscillation in the 40 meter band with a reactive load (antenna). The easy fix for this is to reduce the gain of the predriver board by adjusting the provided gain pot. The better fix that I have arrived at is to increase the negative feedback in the predriver circuit, which reduces the overall gain of the predriver and still allows full power output to be achieved. I've done this only on REV. 2 predrivers, I haven't had a REV. 1 come across my bench yet. 73 -Jim On Sat, 16 Oct 2010 13:00:30 -0400, Garey Barrell wrote: Dave - If the external SWR meter goes to 'infinity' on reflected, then the problem is PAST that meter. The fact that it is ok on a dummy load also indicates an antenna problem. Sounds like an open feedline, - OR - balun, if used. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-B, C-Line& TR-4/C Service Supplement CDs K8JDC wrote: Some more data points: 1. I cannot get the radio to malfunction on a dummy load. I have only seen the problem on 40m when connected to the antenna which is a 135-ft doublet fed with ladder line. Tuner is a Tentec 238B and the tuner is right next to the TR-7. That leads me to wonder if there's some RF from the balanced line that is part of the problem. 2. I checked on 20m and don't see the problem on either a dummy load or my antenna which is a Steppir. Output power is stable. 3. The TR-7 forward meter goes to zero when the problem happens. Reflected indicator goes max scale. So those readings are the same as my external meter. 4. I hooked up my Tentec Orion to the same tuner/antenna and all is well. No hint of anything wrong with the antenna. Output power is totally stable. 5. This problem happens on CW as well as SSB. I have a toggle switch wired to key the radio for tuning and it will put out full power into the antenna for a few seconds and then the reflected power will go to infinity. Power into the dummy load is fine. 6. I did notice at least once that the problem occurred just as I unkeyed in CW mode. So, just as I unkeyed, I saw the reflected power jump high. So, the above leads me to wonder about the transmit relay. I wondered if the contacts are somehow dirty but I don't see the problem on the dummy load so that leads me to wonder if the T/R relay is somehow being affected by some RF from the ladder line which is nearby. It's not easily possible to separate the radio and tuner any more because of how my desk is laid out. The ladder line comes out of the tuner and goes to the left to the outside world. The TR-7 sits just to the right of the tuner so the ladder line does not go behind the radio although it's only about 10 inches away from the T/R relay when it exits the tuner. ?? Dave K8JDC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-7 - More Info Cont'd
To everybody who has written thus far, I thank you. Still working on it... - I have double-checked the ground connections on the tuner and radio. All is good there. - To Gary who suggested that the external tuner indicated that the problem was past that point, I hooked my Tentec up to the same tuner/antenna and it is rock solid at full power output into the same configuration. I also don't think I have a break in the ladder line for the same reason. I have connected my MFJ-259 to the tuner input and the antenna is about 58+j7 in terms of impedance. Looks rock solid on the 259...no fluctuation. - I can't induce the problem on 20m...only 40m. I ran 20m CW into the same doublet/ladder line antenna and it's fine...at least through a short test. - During testing, I notice that I can induce the problem by unkeying the radio a fairly high percentage of the time. So, if I put it in CW and key up, all will be well until I unkey. When I unkey, the reflected power will frequently jump. Same on SSB if I key the mic with no input audio. If I just key the mic with basically zero RF going out and then unkey, I will see the reflected needle jump when I let off the PTT switch. This is what had me thinking about the T/R relay. I tried this on 20m and didn't see the same thing. It operated normally. When I aligned this radio (I don't recall the exact S/N but I think it's around 4900), I had trouble keeping it from oscillating when I followed the instructions. I tried to follow the service manual carefully but it wanted to oscillate. I had to fiddle with it a fair amount going between the two adjustment pots to make it happy. Maybe it's still too hot. My meter says I'm getting about 125W out on 40m. Dave K8JD ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] D-104 microphone wiring question (solved)
Thanks to you all who replied to my question about the microphone hook-up. Got it working... Best regards, 73, Joe WW8X ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Proper Use of DeOxit
I seem to recall reading that there was a right way to use DeOxit, and specific areas where you shouldn't use it at all., but I can't pull the details out of memory. (There were stories about connections not being made any longer, phenolic wafers swelling and switches not working, lubrication being disolved and shafts no longer turning -- I just don't remember which of those related to DeOxit or it's inappropriate use). I believe you shouldn't get this stuff anywhere near the PTO. I just purchased some DeOxit D5, and was intending to use it to clean a bandswitch, and antenna selector switch on an MN-2000. I've also got an R-4B and T-4X that I wanted to go thru the bandswitches, pots, etc on. Additionally, I recently acquired some other boatanchor hardware manufactured by a company starting with Hallicrafter (didn't want to mention other equipment on the Drakelist) that I'd like to do the same with. Can anyone list the do's and dont's about DeOxit so I don't trash otherwise perfectly good hardware? Thanks, Phil WA2CLX ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info Cont'd
On Sat, 16 Oct 2010 16:50:50 -0400, K8JDC wrote: >I had trouble keeping it from oscillating when I followed >the instructions. I tried to follow the service manual carefully but it >wanted to oscillate. I had to fiddle with it a fair amount going >between the two adjustment pots to make it happy. Maybe it's still too >hot. My meter says I'm getting about 125W out on 40m. > I would bet that if you had a frequency counter coupled to it, you would find that it is oscillating somewhere in the 9 MHz area. That is the symptom of the 40 Meter oscillation problem that I found. 125 Watts is below the spec that Drake says to align it to, so you should be able to get more out. I would have to go back and look at my notes, but I think 330 Ohms paralleled across R2203 on the REV. 2 predriver board was what I used to increase the amount negative feedback at lower frequencies. It may be possible or necessary to go even lower in value, but this is what worked for me on two samples that I had. I was just able to make rated output through adjustment of the predriver pot and ALC pot without oscillation. It's hard to get it to oscillate into a dummy load, it seems to need an antenna to take off. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info
On Sat, 16 Oct 2010 15:43:01 -0400, Garey Barrell wrote: > >Is that a possibility? If the antenna is tuned to 20M by the tuner, and >the transmitter is putting out 40M RF, then the transmitter is seeing a >mismatch and 'shuts down'. Does it 'really' go to ZERO power or is it >just rolled back to 20 or so Watts? Actually, the oscillation seems to be inherent in the bandswitch segment that covers 40 Meters. I was able to see it in any 500 KHz segment of that range, and the actual frequency of the oscillation was in the area of 9 MHz, regardless of which 500 KHz segment of that range that I was in. So, any antenna resonant in a ham band would have high VSWR at the freqency of oscillation. In power testing on a dummy load, I did seem to see a shallow peak in output around 9 MHz, and for some reason this is what suggested to me that the gain somewhere in the predriver might be too high in that area. I ceased further investigation once I found a fix that worked. Maybe somone who has the proper software could model the REV. 2 predriver and see what crawls out. >BUT, if you put 40M RF into a tuner set for 20M why would the external >power meter show high reflected power? Unless enough 40M RF is getting >through the tuner to see the mismatched antenna > >My head hurts Worth looking into. What puzzles me is the behaviour of the forward power meter. IIRC, in the units that I had here, the forward power was quite high when it was oscillating. Almost like full power CW. Maybe it's some difference in the way the rigs were adjusted. WTF? Interesting problem. 73 -Jim -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://radiojim.exofire.net http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D-104 microphone wiring question
Jim Shorney... thanks for that great advice about Google... I'll have to check that out sometime. Amazing, you can actually search for information and get answers? Who would of ever thought?? HI HI... 73 Joe ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Proper Use of DeOxit
Well, Walker, since I don't see anyone jumping in here to answer you, let me take a stab at it. First, DeOxit should be used sparingly, like a drop at a time, and NEVER sprayed on a bandswitch, or like switch with phenolic wafers. I use a toothpick (or insulin syringe if I can find them) to put a drop right where I want it on the contact, then work the switch several times to work it in. I put a drop in each hole of a tube socket and work the tube gently to get it distributed. I would advise being careful of using it around front panels, plastic pieces etc without testing a small area. I don't think it is caustic or harmful, but these cosmetic parts are not easily found if damaged. I don't see too much lubricant, if any, in DeOxit, so don't think it is good long term for use in potentiometers. Caig has other products for that (like Faderlube or something like that). Maybe that will give you a start, then others can chime in with better details, hi. 73, Don, WB5HAK ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] T-4X Questions
Regarding the bias setting of 70ma, what is the impact of lower bias setting ( say 60ma )? Regarding neutralization, this transmitter seemed to need neutralizing based on behavior on 40M. On 15M, the neutralization seems exactly "on" ( maximum output at minimum plate current ). What would explain this behavior? Thanks & 73, Curt KB5JO___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-7 Update
Sorry for hogging the Drakelist today... I backed off the pot on the predriver board and it's happy so far. I backed it off very slightly and it still oscillated on 40m so I had to go further. I think I still have about the same output power and I think the ALC LED is still coming on correctly so I think it is okay. I still have good power on 10m through 80m. I was careful during the alignment to not set that pot too high. Makes me wonder if something has drifted in value. I slid it back into position and have been testing it on the antenna and have not seen any more oscillating. I'll have to keep an eye on it. Dave K8JDC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Proper Use of DeOxit
I like to use the DeOxit Pen for tube pins, pilot lamps, cinch connector pins, etc. For relay contacts, I saturate small strips of card stock with deoxit spray, then run them through (do the same for phone jacks and others that have a break/make contact in there. I use the concentrate in the "nail polish" bottle format for contacts that are easy to get at. I use the spray for hard-to-get-at switch wafers, but sparingly where needed (I probably shouldn't be doing that, but have not had any problems for past 10 years or so. 73 Mark N5KAE - Original Message > From: Don Cunningham > To: Walker ; drakelist@zerobeat.net > Sent: Sat, October 16, 2010 6:25:03 PM > Subject: Re: [Drakelist] Proper Use of DeOxit > > Well, Walker, since I don't see anyone jumping in here to answer you, let me >take a stab at it. First, DeOxit should be used sparingly, like a drop at a >time, and NEVER sprayed on a bandswitch, or like switch with phenolic wafers. > > I use a toothpick (or insulin syringe if I can find them) to put a drop right >where I want it on the contact, then work the switch several times to work it >in. I put a drop in each hole of a tube socket and work the tube gently to >get >it distributed. I would advise being careful of using it around front panels, >plastic pieces etc without testing a small area. I don't think it is caustic >or >harmful, but these cosmetic parts are not easily found if damaged. > > I don't see too much lubricant, if any, in DeOxit, so don't think it is good >long term for use in potentiometers. Caig has other products for that (like >Faderlube or something like that). > > Maybe that will give you a start, then others can chime in with better > details, >hi. > 73, > Don, WB5HAK > > ___ > Drakelist mailing list > Drakelist@zerobeat.net > http://mailman.zerobeat.net/mailman/listinfo/drakelist > ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-7 - More Info Cont'd
?I was plagued with the 40M oscillation problem with the same symptoms - a 40M antenna with a bit of reactance resulted in the oscillation. I decided to build the PIN diode attenuator per the PA1HFO design and solved the problem that way. That allows you to set the signal level fed to the pre-driver stage to a different level on each band. You can then adjust each band so that the drive control can be left in the same position as you switch bands and you don't have to adjust it for every band change. With the input signal thus attenuated on 40M, the oscillation was never heard from again. There are other advantages to the attenuator and the whole thing is described in an article on WB4HFN's site. The mods to the original TR7 are minimal - the attenuator sits in the coax feed to the PA brick and you have to pick up the supply voltage and band switch information from points on the motherboard. The entire mod can be removed in very short order if desired. 73, K8AC - Original Message - From: "Jim Shorney" To: Sent: Saturday, October 16, 2010 6:09 PM Subject: Re: [Drakelist] TR-7 - More Info Cont'd On Sat, 16 Oct 2010 16:50:50 -0400, K8JDC wrote: I had trouble keeping it from oscillating when I followed the instructions. I tried to follow the service manual carefully but it wanted to oscillate. I had to fiddle with it a fair amount going between the two adjustment pots to make it happy. Maybe it's still too hot. My meter says I'm getting about 125W out on 40m. I would bet that if you had a frequency counter coupled to it, you would find that it is oscillating somewhere in the 9 MHz area. That is the symptom of the 40 Meter oscillation problem that I found. 125 Watts is below the spec that Drake says to align it to, so you should be able to get more out. I would have to go back and look at my notes, but I think 330 Ohms paralleled across R2203 on the REV. 2 predriver board was what I used to increase the amount negative feedback at lower frequencies. It may be possible or necessary to go even lower in value, but this is what worked for me on two samples that I had. I was just able to make rated output through adjustment of the predriver pot and ALC pot without oscillation. It's hard to get it to oscillate into a dummy load, it seems to need an antenna to take off. 73 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
