Re: [Drakelist] R-4C PTO Hum
Garey, Thanks for the tip. I did check with John, but no luck. However, I may have found an alternative. Newark has Plastic Snap Rivets that may work. http://www.newark.com/jsp/content/printCatalog.jsp?cat=catalog128page=2137display=single I'll order a pack and try them. Seems like missing chassis bumpers are a common problem after the receivers are repeatedly turned upside down for shop work. Paul, W9AC ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R-4C Power Transformer Rotation
Mu metal can be found in some old TVs (not all), oscilloscopes, etc. at low to free prices... -Original Message- From: Paul Christensen w...@arrl.net To: Drakelist group drakelist@zerobeat.net Sent: Wed, Jul 6, 2011 7:26 am Subject: [Drakelist] R-4C Power Transformer Rotation As promised, here's my update concerning the R-4C power transformer and PTO modulation. First a special thanks to Bill, W6FF for providing me with a NOS R-4C transformer. Very much appreciated. However, a rare occurrence of good fortune came to me. It turns out that the existing R-4C transformer can be rotated 90 degrees and still have enough lead length on the transformer wiring to terminate the end points -- at least on my R-4C. Since transformer installation and wire termination was a manual process at Drake, exact lead lengths will differ. That said, I had more than enough wire length to accomplish the task without having to try the NOS transformer. In the links to images below, you can see the transformer after rotation as well as a ground lug added the PTO shield. The addition of the lug was suggested by Rob Sherwood in his PowerPoint presentation. He reasoned that the spade mounting forks do not always make good metal contact with the PTO frame to adequately allow for good PTO shielding -- although aluminum is a relatively ineffective shield against low frequency flux. In his case, he was able to attain a 10 dB reduction in flux induction with the addition of the ground lug. http://72.52.250.47/images/R4C.jpg http://72.52.250.47/images/R4C-1.jpg The rotation worked. At no point of VFO rotation can I detect PTO carrier modulation. This is not to say that it is 100% eliminated. A spectrum analyzer is needed to ensure absolute PTO oscillator purity. However, any remaining level of induced flux has now dropped down to the point of being inaudible. I'm saving my pennies for an HP 8591E spectrum analyzer w/ tracking generator. Every time I save enough, temptation comes over me like it did last Thursday when I purchased a mint S/Line. When I do obtain the SA, I plan on making more tests, including effects with Mu-metal shielding. I'm still looking for a source of authentic Mu-metal sheeting. I was also concerned about potential mechanical interference to the crystal calibrator board with the transformer rotated. Good news again. There's still ample room to insert/extract the calibrator board to/from its socket. No issues here. Transformer re-mounting: Even more good news. Unlike the R-4B transformer, the R-4C transformer mounting centers form a perfect square and the existing chassis holes are fine for mounting after rotation. However, new chassis access holes ARE required for the transformer wiring. I used a Greenlee 3/4 chassis punch to form two new holes. The chassis is still plenty strong after inclusion of the new holes, especially since the transformer mounting frame helps to ensure that the chassis remains rigid after bolt tightening. For anyone contemplating transformer rotation, it's a good idea to first pave the way for a chassis punch. I temporarily removed the chassis fuse holder and AC line select switch. This gave me all the room I needed without causing damage (and I'm good at causing damage to my gear in the shop). Before removal of these two items, I drew a sketch to help remind me of wiring placement. A quick snapshot with a digital camera is also a good idea. Paul, W9AC ___ 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] R4A AVC Question
With my R4A s/n 6759, have distortion of a sideband signal when RF gain control at maximum, AVC on fast. CW signal is normal, and there is no distortion with the AVC off or on slow or with RF gain lower. I'm recalling the AVC setup can be difficult to get right, appreciate any advice before beginning to work on this issue. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R-4C Cabinet Bumpers
To Add to Paul's Request I am also looking for several bumper replacements. I have not found a source for these as of yet and would appreciate any advice from the group. Thank-you Wade, VA3HM From: w...@arrl.net To: drakelist@zerobeat.net Date: Tue, 5 Jul 2011 17:56:33 -0400 Subject: [Drakelist] R-4C Cabinet Bumpers With all the R-4C work going on here, I have managed to loose (or break and then loose) the two small top cabinet bumpers located at the top rear of the R-4C. These are black in color, flat, and are press-fit into the back top lip of the chassis. Anyone have a pair to sell or is the OEM still selling them through a distributor? Tnx! Paul, W9AC ___ 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] S-Meter hiccup on warm-up
Hello all, I'm new to the world of Drakes and have a question re: possible normal v. abnormal behavior. Several months ago I purchased a R-4B. After re-capping the radio works wonderfully, and is a joy to use. My question: when I first turn it on and place it in standby to warm-up, the S-meter moves smoothly to the right, but always hiccups at 9 (mid-point) before moving all the way to the right. Is this a normal behavior, or indicative of a problem? Thanks for any help/insights you might offer, jake --- Jakob Crockett Archaeology Coordinator Historic Columbia Foundation 1601 Richland Street Columbia, South Carolina 29201 http://mannsimons.freehostia.com KK4BPB ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R4A AVC Question
I'd start by replacing V5 if you have a spare. If not, just swap with V4. If no effect, replace V1 and/or V4. If still no luck, we'll have to make some measurements in and around Q4. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com rhule...@comcast.net wrote: With my R4A s/n 6759, have distortion of a sideband signal when RF gain control at maximum, AVC on fast. CW signal is normal, and there is no distortion with the AVC off or on slow or with RF gain lower. I'm recalling the AVC setup can be difficult to get right, appreciate any advice before beginning to work on this issue. ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] R-4C Cabinet Bumpers
- Original Message - From: wmacle...@sympatico.ca To: drakelist@zerobeat.net Sent: Wednesday, July 06, 2011 7:43 AM Subject: Re: [Drakelist] R-4C Cabinet Bumpers To Add to Paul's Request I am also looking for several bumper replacements. I have not found a source for these as of yet and would appreciate any advice from the group. Thank-you Wade, VA3HM Is there an illustration of these bumpers anywhere? I've seen all sorts of bumpers and feet at places that sell luggage repair parts and some other places, but I don't know exactly what is being looked for. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] S-Meter hiccup on warm-up
Jake - Some do, some don't. I think it is a function of the warm-up times of the various tubes involved, primarily V1, V4 and V5. They're all specified as 11 second warm-up, but the precise point where they just begin to conduct can vary slightly. Once warmed-up, you should be able to adjust the RF GAIN control and cause the meter to run smoothly from S1 to S9 +60. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com jakob crockett wrote: Hello all, I'm new to the world of Drakes and have a question re: possible normal v. abnormal behavior. Several months ago I purchased a R-4B. After re-capping the radio works wonderfully, and is a joy to use. My question: when I first turn it on and place it in standby to warm-up, the S-meter moves smoothly to the right, but always hiccups at 9 (mid-point) before moving all the way to the right. Is this a normal behavior, or indicative of a problem? Thanks for any help/insights you might offer, jake ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Connector for L7-PS
Gentlemen, I am currently after an L7 missing the power supply. It will not be a big problem to build a decent p/s but will I be able to get that 8-pole connector? Especially here in Germany it is probably hard to get. Can you give me some sourcing hint? Thanks and 73 Dieter Sam DL5RDO TR-7/R7 ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake R-4C Power Transformer Orientation
Rob Sherwood just sent me the data below, confirming my finding that AC flux induction is worse on the R-4C PTO when the VFO is run up top where the ferrite core extends furthest to the rear of the receiver. Notice the 13 dB difference in modulated PTO 60 Hz sidebands between VFO extremes. Rob will send me his before and after transformer rotation spectrum measurements. I'll post here when completed. Paul, W9AC I measured the ripple on the PTO at three frequencies on an R-4C in here for service using my HP 3585A spectrum analyzer. The value is for the line related sidebands on two of the frequencies, and sidebands at 120, 180, 240 Hz on the highest frequency. The line-related sidebands go out further than 240 Hz, and are down about 80 dB at 480 Hz Receiver freq.60 Hz 120 Hz 180 Hz 240 Hz Tuned 14.0 MHZ -46 dB Tuned 14.2 MHZ -39 dB Tuned 14.5 MHZ -33 dB, -48 dB, -57 dB, -63 dB Of course the band one is on makes no difference, as the hum sidebands are magnetically coupled into the PTO. I will have my tech turn around a transformer on one of my C-Lines in the coming weeks. 73, Rob, NC0B ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Drake 2B General Coverage
OK, guys, I have been using my Drake 2B as a general-coverage receiver for a week now and I wanted to report back on my experiences. This is a receiver that you folks helped me out with about a month ago. To repair it, I had to install a 6BF6 tube (easily obtained) and replace the filter cap can. I made it a general-coverage receiver by using the accessory crystal sockets B, C and D. A 10 mhz crystal gives me 49m, a 13.5 mhz crystal gives me 31m and an 8.0 mhz crystal gives me 25m. The stock crystal for 40m includes the 41m band. The receiver's sensitivity and selectivity are very good. The tuning is spot-on accurate. While the audio does not rival that of an SX-28 or NC-183d, it is more than acceptable. I am really impressed. This receiver is a keeper. I have this set in my study and use it for general SWLing as well as monitoring the ham bands. It's a fun set to use. There are shortcomings: (1) you have to buy the crystals for each SW band; (2) it's a royal pain to change crystals. The 2B's top does not open, which would make changing the crystals less of a chore. Thus, I am pretty much limited to the SW bands listed above. This is a significant limitation. For example, I would like to be able to monitor the 19m band; and (3) I have yet to master the 2B-Q Q multiplier. Joe Connor___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] [Boatanchors] Drake 2B General Coverage (Addition)
I should add that another shortcoming of the 2B is that it cannot receive below 3.5 mhz without a special low frequency converter. That's a shame because it seems this would be a great set for BCB DXing. Here are some details on the converter: http://www.dproducts.be/drake_museum/2-lf1.htm If anyone has one for sale, please let me know. Joe Connor From: Joe Connor joeconno...@yahoo.com To: Mail List - Drake Gear Drake Gear drakelist@zerobeat.net Cc: boatanch...@mailman.qth.net boatanch...@mailman.qth.net Sent: Wednesday, July 6, 2011 8:01 PM Subject: [Boatanchors] Drake 2B General Coverage OK, guys, I have been using my Drake 2B as a general-coverage receiver for a week now and I wanted to report back on my experiences. This is a receiver that you folks helped me out with about a month ago. To repair it, I had to install a 6BF6 tube (easily obtained) and replace the filter cap can. I made it a general-coverage receiver by using the accessory crystal sockets B, C and D. A 10 mhz crystal gives me 49m, a 13.5 mhz crystal gives me 31m and an 8.0 mhz crystal gives me 25m. The stock crystal for 40m includes the 41m band. The receiver's sensitivity and selectivity are very good. The tuning is spot-on accurate. While the audio does not rival that of an SX-28 or NC-183d, it is more than acceptable. I am really impressed. This receiver is a keeper. I have this set in my study and use it for general SWLing as well as monitoring the ham bands. It's a fun set to use. There are shortcomings: (1) you have to buy the crystals for each SW band; (2) it's a royal pain to change crystals. The 2B's top does not open, which would make changing the crystals less of a chore. Thus, I am pretty much limited to the SW bands listed above. This is a significant limitation. For example, I would like to be able to monitor the 19m band; and (3) I have yet to master the 2B-Q Q multiplier. Joe Connor __ Boatanchors mailing list Home: http://mailman.qth.net/mailman/listinfo/boatanchors Help: http://mailman.qth.net/mmfaq.htm Post: mailto:boatanch...@mailman.qth.net List Administrator: Duane Fischer, W8DBF ** For Assistance: dfischer at usol.com ** This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] D104 and TR7
*Does any one know the mod to make the 104 work well with the TR7, I was told you added a **resistor of some value but they didn't know the value or where to put it. I need to know it at the Mod's for Dummies level, I was a Toolmaker not a electronics man, well just enough to be dangerous and stay alive. * Thanks Woody -- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D104 and TR7
Woody, You can add a 100K resistor in the D104's + mic lead. That will help to unload the crystal element from the TR-7's moderately low input Z. Same is true if your D104 uses Astatic's 2-transistor preamp/buffer circuit. The input Z of Astatic's preamp is still too low to take full advantage of an unloaded crystal mic element. On the other hand, the TR-7's SSB transmit filter will strip away much of the full-bodied audio from the D104. So, apart from adding the 100k resistor, I wouldn't change anything else. If you were going to use the D104 with a modern DSP-based transceiver, I would have suggested gutting the Astatic preamp and replace it with one of the FET buffer circuits shown on my QRZ.com page. Paul, W9AC - Original Message - From: Woody To: Drake List Sent: Wednesday, July 06, 2011 9:19 PM Subject: [Drakelist] D104 and TR7 Does any one know the mod to make the 104 work well with the TR7, I was told you added a resistor of some value but they didn't know the value or where to put it. I need to know it at the Mod's for Dummies level, I was a Toolmaker not a electronics man, well just enough to be dangerous and stay alive. Thanks Woody -- -- ___ 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] D104 and TR7
Woody, I've heard of numerous people using the D-104 with the TR-7 as discussed on the Drake nets. Values I've heard range from 470K to 1.3 meg in series with the mic hot lead. If there is a speech pre-amp in the mic, it should not be used. 73, Evan, K9SQG -Original Message- From: Woody ko4...@gmail.com To: Drake List drakelist@zerobeat.net Sent: Wed, Jul 6, 2011 9:19 pm Subject: [Drakelist] D104 and TR7 Does any one know the mod to make the 104 work well with the TR7, I was told you added a resistor of some value but they didn't know the value or where to put it. I need to know it at the Mod's for Dummies level, I was a Toolmaker not a electronics man, well just enough to be dangerous and stay alive. Thanks Woody -- ___ 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] D104 and TR7
Why wouldn't you use the preamp? While there may be better preamp circuits out there, even the preamp in an amplified Astatic stand sounds decent if it's used properly. Turn it all the way down. Set the rig's mic gain at about 10:00, and then SLOWLY advance the gain of the preamp for normal modulation. The biggest problem happens when you just crank it all the way up for that good buddy effect. I've used amp'd d104 and 10D mics on rigs of all kinds (including Drake's of all kinds without getting cr*p for audio. The preamp eliminates the need to be concerned about matching the input Z of the radio and eliminates the effect of the input Z of the radio on the freq response of the mic. Grant/NQ5T Sent from my iPhone On Jul 6, 2011, at 8:47 PM, K9sqg k9...@aol.com wrote: Woody, I've heard of numerous people using the D-104 with the TR-7 as discussed on the Drake nets. Values I've heard range from 470K to 1.3 meg in series with the mic hot lead. If there is a speech pre-amp in the mic, it should not be used. 73, Evan, K9SQG -Original Message- From: Woody ko4...@gmail.com To: Drake List drakelist@zerobeat.net Sent: Wed, Jul 6, 2011 9:19 pm Subject: [Drakelist] D104 and TR7 Does any one know the mod to make the 104 work well with the TR7, I was told you added a resistor of some value but they didn't know the value or where to put it. I need to know it at the Mod's for Dummies level, I was a Toolmaker not a electronics man, well just enough to be dangerous and stay alive. Thanks Woody -- ___ 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 mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Amplified D104
*I have used D104's for many years on all my rigs, as a matter of a fact that's all I own, I have mine mounted on a boom, I hate to hold the darn things. This is the only time I have ever had a problem with one, and I have the amp tuned all the way down and then just barely cracked it and the mic gain on the TR7 is at the 7 o'clock position if you turn it up passed that position I get bad reports of clipping. So I'm trying to find a cure without going to a 7075 for close to a hundred bucks and having to hold it. * *Woody *-- ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Amplified D104
444D -- hamfest, e-whatever. Not expensive. Great mic with a TR-7. Sent from my iPhone On Jul 6, 2011, at 9:40 PM, Woody ko4...@gmail.com wrote: I clipping. So I'm trying to find a cure without going to a 7075 for close to a hundred bucks and having to hold it. Woody -- ___ 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] D104 and TR7
That's true. But if one has an amplified stand it will work fine, too. Sent from my iPhone On Jul 6, 2011, at 10:13 PM, K9sqg k9...@aol.com wrote: Grant, There is no real need for the pre-amp circuit when the D-104 is used with the TR-7, more than enough gain exists. Don't have to replace the battery every year or two either. At any rate, it is personal preference. 73, Evan - ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Amplified D104
On Wed, 6 Jul 2011 21:40:29 -0500, Woody wrote: I have used D104's for many years on all my rigs, as a matter of a fact that's all I own, I have mine mounted on a boom, I hate to hold the darn things. This is the only time I have ever had a problem with one, and I have the amp tuned all the way down and then just barely cracked it and the mic gain on the TR7 is at the 7 o'clock position if you turn it up passed that position I get bad reports of clipping. So I'm trying to find a cure without going to a 7075 for close to a hundred bucks and having to hold it. Two things: 1. Make sure you are connected to the high level input pin on the TR-7 mic connector. That's the pin with the extra 470K resistor in series with the audio line (on all but the earliest TR-7s). 2. Disconnect that abomination of an amplifier and place an additional 470K (or higher) series resistor in it's place. You don't need the extra gain at all, as you have found out, and the higher impedance load on the D-104 cartridge will make it sound very good. I've used two different D-104/T-UGx on my TR-7 using both these methods at the same time, with stellar audio reports. 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D104 and TR7
On Wed, 6 Jul 2011 22:26:44 -0500, Grant Youngman wrote: That's true. But if one has an amplified stand it will work fine, too. Better without. It's extra gain that is not needed, and it adds another failure point and a point for feedback and distortion to enter. I've gotten excellent results by removing the amlifier and using the old-timer's trick of the series 470K resistor. The result beats out most of my other mics, although the Turners and the EV are real close. 444 and 7075, not so much, although the 444 gets the a nod for it's natural sound suitable for casual armchair copy QSOing. 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D104 and TR7
On Wed, 6 Jul 2011 21:23:08 -0500, Grant Youngman wrote: Why wouldn't you use the preamp? Because you don't need it, and it can cause more trouble than it's worth. The preamp eliminates the need to be concerned about matching the input Z of the radio and eliminates the effect of the input Z of the radio on the freq response of the mic. No concern at all with the Drakes, see my previous posts. The cartridge has high output, and the higher the load impedance, the better they tend to sound. I always got exellent reports feeding through a collective total of close to 1 Meg resistive into the TR-7. 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D104 and TR7
On Wed, 6 Jul 2011 21:33:11 -0400, Paul Christensen wrote: You can add a 100K resistor in the D104's + mic lead. That will help to unload the crystal element from the TR-7's moderately low input Z. Note: if the high level input pin is used, the load is 470K + the low level impedance. I use 470K for the series resitor, for a total of around a meg. If you were going to use the D104 with a modern DSP-based transceiver, I would have suggested gutting the Astatic preamp and replace it with one of the FET buffer circuits shown on my QRZ.com page. I should think that the resistor method would work with just about any rig that will accept a low-Z dymanic mic. 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Connector for L7-PS
Dieter, This is a standard Jones connector, formerly made by Cinch. I purchased one from, I think, Digi-Key several years ago. I don't know if this particular connector is still in production, but there should still be NOS available at one or more of the major parts suppliers. 73 -Jim On Wed, 06 Jul 2011 20:57:02 +0200, Dieter Horst wrote: Gentlemen, I am currently after an L7 missing the power supply. It will not be a big problem to build a decent p/s but will I be able to get that 8-pole connector? Especially here in Germany it is probably hard to get. Can you give me some sourcing hint? Thanks and 73 Dieter Sam DL5RDO TR-7/R7 ___ 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://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] D104 and TR7
- Original Message - From: Jim Shorney jshor...@inebraska.com To: drakelist@zerobeat.net Sent: Wednesday, July 06, 2011 9:16 PM Subject: Re: [Drakelist] D104 and TR7 On Wed, 6 Jul 2011 22:26:44 -0500, Grant Youngman wrote: That's true. But if one has an amplified stand it will work fine, too. Better without. It's extra gain that is not needed, and it adds another failure point and a point for feedback and distortion to enter. I've gotten excellent results by removing the amlifier and using the old-timer's trick of the series 470K resistor. The result beats out most of my other mics, although the Turners and the EV are real close. 444 and 7075, not so much, although the 444 gets the a nod for it's natural sound suitable for casual armchair copy QSOing. 73 -Jim FWIW, crystal and ceramic microphones have purely capacitive internal impedance, that is they look like a capacitor. Ideally, they want to look at in infinite impedance. When you put it in parallel with a resistor it forms a high pass filter, that is, the bass will be rolled off. A series resistor will keep the low end up at the expense of some loss of level. The other thing to be careful of is cable capacitance. That will tend to roll off the high frequencies because the impedance of the mic is so high. Probably the ideal input device is a vacuum tube with an open grid or one with grid leak bias. There is probably a solid state equivalent to that. I am somewhat surprized that the frequency responce is affected enough to be heard through the rather narrow and sharp filters in modern SSB rigs. -- Richard Knoppow Los Angeles WB6KBL dickb...@ix.netcom.com ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
