RE: [drakelist] 2nd IF Audio Board in TR7
Carel PA0CMU [EMAIL PROTECTED] made an utterance to the drakelist gang -- Garey - K4OAH wrote: Your link below refers me to your Host's lost page. Perhaps it's referring to a TMP folder on your machine? No Garey, I changed the first three characters to lower case in the link, but the real filename was in uppercase. It is corrected now. Please look again. http://home.wanadoo.nl/cmulder/tmp/dsc02639a.jpg Although the resistors R1187 and R1188 are drawn in my schematic (Service Manual 1978), they were NOT designed on the PC-board. I added them by lifting the diodes on one side. http://home.wanadoo.nl/cmulder/tmp/R1187.jpg http://home.wanadoo.nl/cmulder/tmp/R1188.jpg Carel - PA0CMU. _ De leukste online filmpjes vind je op MSN Video! http://video.msn.com/video.aspx?mkt=nl-nl -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
Re: [drakelist] 2nd IF Audio Board in TR7
David Chris Drake [EMAIL PROTECTED] made an utterance to the drakelist gang -- Garey, Thanks for the link. My current TR7 has the first gen. board. Its mid 5900's, so your cutoff must be about right. I've 'heard' people say that the 2nd gen audio is much better, but you know what they say about perception versus reality. Perception is 90% of reality to many people. So when drake improved the specs, well, you know what I'm getting at. Thanks again, David Wd9cmd - Original Message - From: Garey Barrell [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Thursday, April 24, 2008 6:58 PM Subject: Re: [drakelist] 2nd IF Audio Board in TR7 Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- David - I just had this conversation the other day...! :-) I don't think anyone knows for sure, but I believe the AF board change was made around s/n 6000 or so. Early 1980. According to Bill Frost, the 1496 was originally designed into the R-7, and was then adopted as a cost saving measure in the second generation TR-7. The IC replaced a hand wound toroid and a couple of alignment problems. It's pretty easy to spot in a TR-7, as it's right at the top right corner of the 2nd IF/AF board at the rear of the card cage. Version 1 has the toroid up there and a little U-shaped shield (yet another costly item not needed with the IC) while the Version 2 board has the IC and a few resistors. Personally, I doubt if you would notice the difference by ear. I have a couple of each, and can't say that I can hear the difference. Yeah, the 1496 has a wider dynamic range than the two diode PD, but the AGC kinda eliminates the advantage of wide dynamic range! I think it was purely cost saving, and a fancier set of specs couldn't hurt! :-) A dutch ham did a conversion by removing all the parts associated with the Version 1 and putting the 1496 on a small piece of perfboard mounted just above the original board. http://home.wanadoo.nl/cmulder/drake.htm#bookmark3 I'm sure we'll hear other opinions!! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com David Chris Drake wrote: Hi all, Couple questions: Is there a significant performance difference between the first and second version 2nd IF/Audio boards?. I believe Drake changed to the newer version along the time the R7 came out, but not sure exactly. And: If the answer to the first question is affirmative, then is there anyone out there who has performed the upgrade on and early board? Good results? Thanks, David Wd9cmd -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net -- -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
RE: [drakelist] 2nd IF Audio Board in TR7
Carel PA0CMU [EMAIL PROTECTED] made an utterance to the drakelist gang -- Garey, Not only the demodulator circuit was changed. 1. Drake made some minor changes in the S-meter circuit. R1101 is replaced by two 1N4148 diodes in series and CR1101 is replaced by a 4700 Ohm resistor. 2. My first generation board was missing the current limiting resistors R1187 and R1188 (feeding the audio preamps Q and Q1113) causing loud clicks in the speaker when switching to CW and AM mode. 3. R1112 was connected between base and collector of Q1103 in stead of biasing the base from the +10V-DC (pin11/13) line. The effect was a short pulse to the RTx relay when switching to CW mode. All mentioned above is drawn correctly in the first generation schematic Fig. 2-22 2nd IF/Audio Board on page 2-63 of the Service Manual. Unfortunately my board was not build like that. I cannot say the TR7 sounds or performs better after the upgrade to a second generation board. I just replaced the demodulator circuit by a MC1496. Meanwhile I added a switched capacitor audio filter as described on my homepage and placed it on top of the piggy back mounted PC-board holding the MC1496 circuit. Here is a link to one of the pictures I still have to add to the Drake page of my website. http://home.wanadoo.nl/cmulder/tmp/dsc02639a.jpg The upper board is the audio filter with MAX7400. The lower one is the product detector. All build very compact to fit in the compartment just behind the fan connector (changed to a 12V-DC type). That filter is doing a very great job, clearing the high hiss in my headphones when listening CW signals. Carel - PA0CMU http://home.wanadoo.nl/cmulder Date: Thu, 24 Apr 2008 18:58:35 -0400 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [drakelist] 2nd IF Audio Board in TR7 Garey Barrell made an utterance to the drakelist gang -- David - I just had this conversation the other day...! :-) I don't think anyone knows for sure, but I believe the AF board change was made around s/n 6000 or so. Early 1980. According to Bill Frost, the 1496 was originally designed into the R-7, and was then adopted as a cost saving measure in the second generation TR-7. The IC replaced a hand wound toroid and a couple of alignment problems. It's pretty easy to spot in a TR-7, as it's right at the top right corner of the 2nd IF/AF board at the rear of the card cage. Version 1 has the toroid up there and a little U-shaped shield (yet another costly item not needed with the IC) while the Version 2 board has the IC and a few resistors. Personally, I doubt if you would notice the difference by ear. I have a couple of each, and can't say that I can hear the difference. Yeah, the 1496 has a wider dynamic range than the two diode PD, but the AGC kinda eliminates the advantage of wide dynamic range! I think it was purely cost saving, and a fancier set of specs couldn't hurt! :-) A dutch ham did a conversion by removing all the parts associated with the Version 1 and putting the 1496 on a small piece of perfboard mounted just above the original board. I'm sure we'll hear other opinions!! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs -- _ Probeer Live Search: de zoekmachine van de makers van MSN! http://www.live.com/?searchOnly=true -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
Re: [drakelist] 2nd IF Audio Board in TR7
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Carel - First, thank you very much for your informative website. We seem to have once again run across Drake's penchant for hardware that doesn't quite match the documentation! :-) The only two docs I have for the 2nd IF/Audio board are the original(?) in a 1978 version of the Service Manual, and another Version 2 Dated October 1980. The first schematic shows CR1101 and the second shows neither the diode nor a resistor. Both schematics show the two diodes in place of R1101, but the second one shows the two diodes AND R1101 in series. Both show the resistors R1187 and 1188. Both show R1112 connected to the +10 VDC bus. Unfortunately the only TR-7 that I currently have access to is a 9k s/n with the Version 2 board in it. Now I'll have to find an earlier one in one of the storage units! :-) Your link below refers me to your Host's lost page. Perhaps it's referring to a TMP folder on your machine? The SpectrumLab plots on your website certainly show the effect of that audio filter. Thanks for replying! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Carel PA0CMU wrote: Carel PA0CMU [EMAIL PROTECTED] made an utterance to the drakelist gang -- Garey, Not only the demodulator circuit was changed. 1. Drake made some minor changes in the S-meter circuit. R1101 is replaced by two 1N4148 diodes in series and CR1101 is replaced by a 4700 Ohm resistor. 2. My first generation board was missing the current limiting resistors R1187 and R1188 (feeding the audio preamps Q and Q1113) causing loud clicks in the speaker when switching to CW and AM mode. 3. R1112 was connected between base and collector of Q1103 in stead of biasing the base from the +10V-DC (pin11/13) line. The effect was a short pulse to the RTx relay when switching to CW mode. All mentioned above is drawn correctly in the first generation schematic Fig. 2-22 2nd IF/Audio Board on page 2-63 of the Service Manual. Unfortunately my board was not build like that. I cannot say the TR7 sounds or performs better after the upgrade to a second generation board. I just replaced the demodulator circuit by a MC1496. Meanwhile I added a switched capacitor audio filter as described on my homepage and placed it on top of the piggy back mounted PC-board holding the MC1496 circuit. Here is a link to one of the pictures I still have to add to the Drake page of my website. http://home.wanadoo.nl/cmulder/tmp/dsc02639a.jpg The upper board is the audio filter with MAX7400. The lower one is the product detector. All build very compact to fit in the compartment just behind the fan connector (changed to a 12V-DC type). That filter is doing a very great job, clearing the high hiss in my headphones when listening CW signals. Carel - PA0CMU http://home.wanadoo.nl/cmulder Date: Thu, 24 Apr 2008 18:58:35 -0400 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [drakelist] 2nd IF Audio Board in TR7 Garey Barrell made an utterance to the drakelist gang -- David - I just had this conversation the other day...! :-) I don't think anyone knows for sure, but I believe the AF board change was made around s/n 6000 or so. Early 1980. According to Bill Frost, the 1496 was originally designed into the R-7, and was then adopted as a cost saving measure in the second generation TR-7. The IC replaced a hand wound toroid and a couple of alignment problems. It's pretty easy to spot in a TR-7, as it's right at the top right corner of the 2nd IF/AF board at the rear of the card cage. Version 1 has the toroid up there and a little U-shaped shield (yet another costly item not needed with the IC) while the Version 2 board has the IC and a few resistors. Personally, I doubt if you would notice the difference by ear. I have a couple of each, and can't say that I can hear the difference. Yeah, the 1496 has a wider dynamic range than the two diode PD, but the AGC kinda eliminates the advantage of wide dynamic range! I think it was purely cost saving, and a fancier set of specs couldn't hurt! :-) A dutch ham did a conversion by removing all the parts associated with the Version 1 and putting the 1496 on a small piece of perfboard mounted just above the original board. I'm sure we'll hear other opinions!! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored
Re: [drakelist] 2nd IF Audio Board in TR7
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- David - I just had this conversation the other day...! :-) I don't think anyone knows for sure, but I believe the AF board change was made around s/n 6000 or so. Early 1980. According to Bill Frost, the 1496 was originally designed into the R-7, and was then adopted as a cost saving measure in the second generation TR-7. The IC replaced a hand wound toroid and a couple of alignment problems. It's pretty easy to spot in a TR-7, as it's right at the top right corner of the 2nd IF/AF board at the rear of the card cage. Version 1 has the toroid up there and a little U-shaped shield (yet another costly item not needed with the IC) while the Version 2 board has the IC and a few resistors. Personally, I doubt if you would notice the difference by ear. I have a couple of each, and can't say that I can hear the difference. Yeah, the 1496 has a wider dynamic range than the two diode PD, but the AGC kinda eliminates the advantage of wide dynamic range! I think it was purely cost saving, and a fancier set of specs couldn't hurt! :-) A dutch ham did a conversion by removing all the parts associated with the Version 1 and putting the 1496 on a small piece of perfboard mounted just above the original board. http://home.wanadoo.nl/cmulder/drake.htm#bookmark3 I'm sure we'll hear other opinions!! :-) 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com David Chris Drake wrote: Hi all, Couple questions: Is there a significant performance difference between the first and second version 2nd IF/Audio boards?. I believe Drake changed to the newer version along the time the R7 came out, but not sure exactly. And: If the answer to the first question is affirmative, then is there anyone out there who has performed the upgrade on and early board? Good results? Thanks, David Wd9cmd -- Submissions:[EMAIL PROTECTED] Unsubscribe:[EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost:[EMAIL PROTECTED] - help in body of message Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net --
