[drakelist] VA7TO 2-B: Drake 2-B Restoration Project Part 1
Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- When I completed my first radio restoration project, an Heathkit GR-81, and announced that my next project would be a Drake 2-B receiver, a few people asked me to post my progress to the mailing list. I will cross post to both the Drake (drakelist@zerobeat.net) and Glowbugs ([EMAIL PROTECTED]) lists. I will also include VA7TO 2-B: in the subject for those who would like to filter messages. I hope that this serves two purposes, first is for me to gain from the experience of others, and learn some tips and tricks and second to document what I have done so that those following me in a 2-B project can learn from my efforts. First of all a little history of my 2-B. I purchased it at the Spokane Hamfest in September of 2007 complete with 2-BQ Q multiplier and speaker. The seller did not know much of the history of the radio, and a quick test at the hamfest showed it received a 40 meter test signal. I paid $275 cash. The radio is in good shape cosmetically and looked fairly clean inside. The receiver immediately went into service as my bedside receiver. I was thoroughly impressed by the audio quality and the selectivity on CW with the Q-multiplier. Hindsight is 20/20 and I wished that I had purchased a 2-B as my first receiver rather than an Hallicrafters SX-140 back in 1975. The 2-B saw regular duty for several months, until one evening it exhibited a loud white noise sound. At that point it was taken out of service and has remained unused. The details on the white noise sound are in this message: http://www.mail-archive.com/[EMAIL PROTECTED]/msg08842.html Last night I pulled the cover off and was surprised to see how clean the inside of the chassis is. It is also a lot easier to work on than I had thought it would be. In operation, the passband control did not seem to line up with the knob markings and I suspected that the knob had been reinstalled incorrectly at some point in the past. Using the information on Garey Barrell, K4OAH's Drake 2-B Service Supplement CD, I was able to confirm that the knob had been placed 90 degrees clockwise from where it should have been and I readjusted it. For a starting reference point I measured all the points listed in the resistance table in the 2-B manual. I was also surprised to see that the measured readings were quite close to those listed in the table. The radio was NOT connected to anything including the power, 2-BQ or speaker, and the controls were set as follows: Preselector: 5 Band: 15 M Power: Off Cal: Off Stby: Rcv AVC: Slow AVC NL: On Detector: Product BFO: On RF Gain: Max (fully clockwise) AF Gain: Max (fully clockwise) Passband: 2.1 kHz and Knob arrow pointed to 12:00 o'clock. Freq: 21.150 Mhz The resistance of pin 3 of V-8 will be altered by the position of the noise limiter (NL) switch. Intially I had the switch off and measured only 346 kilo ohms, rather than the 2.5 mega ohms I should have seen. A quick check of the schematic showed that the switch must be on to reach the specified resistance. The next step was to test the tubes. V-1 (RF amp) and Zenith 6BZ6 - Tested OK V-2 (1st mixer xtal osc) RCA 6U8A - Tested shorted V-3 (2nd mixer vfo) RCA 6BE6 - Tested OK V-4 (3rd mixer) Sylvania 6BE6 - Tested OK V-5 (IF amp) Sylvania 6BA6 - Tested OK V-6 (AVC Amp and AM det) Sylvania 6BF6 - Tested right on the line between good and bad V-7 (Prod Det and BFO) Sylvania 6BE6 - Tested OK V-8 (audio amp) Sylvania 8BN8 - Tested OK V-9 (audio output) Sylvania 6AQ5 - Tested just into the good V-10 (Power Rect) unreadable brand 6X4 - Tested OK Crystal Calibrator Sylvania 6BZ6 - Tested shorted 2-BQ Sylvania 12AX7 - Tested OK I had a spare 6BZ6 of unreadable brand that I substituted into the crystal calibrator and also a spare 6U8A also of unreadable brand that I substituted into V-2. So all the shorted tubes have been replaced, but some low emission tubes should also be replaced. The manual specifies a 6U8 at V-2, but there was a 6U8A there. Should this be replaced with a 6U8? I would guess that the 2-B originally came with all Sylvania tubes. Can anyone confirm this? Are there better brands that anyone would recommend for certain tubes or stages? I would like to replace the 6BF6 (V-6) and the 6AQ5 (V-9) with stronger tubes. I am wondering if I should stay with Sylvania brand tubes or if it matters, or if there are better brands to use. Should I even go so far as to replace the non-Sylvania tubes with Sylvania tubes or other recommended brands? I also have a number of industrial tubes and wonder about tube substitution with some of these. Please reply with your comments and suggestions on what you think I should do about the tubes. While I wait for advice on tubes and then source replacements, I will begin work on recapping, replacing the RF and AF gain pots, and
Re: [drakelist] VA7TO 2-B: Drake 2-B Restoration Project Part 1
Don Cunningham [EMAIL PROTECTED] made an utterance to the drakelist gang -- Darrell, I will be joining you on that journey soon. I just got my 2B/2BQ in this evening (s/n 10040) and it looks to be in nice, unrestored condition. I have always wanted one of these, and looks like I got a fairly clean chassis even! Just a few suspect places from what I can see with the cover on. More later as the project progresses, but it may well be fall/winter with all the gardening and summer activities, hi. Keep us posted, Darrell!! Now, looking for the 2NT to go with it . 73, Don, WB5HAK -- Submissions:drakelist@zerobeat.net 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] VA7TO 2-B: Drake 2-B Restoration Project Part 1
Garey Barrell [EMAIL PROTECTED] made an utterance to the drakelist gang -- Darrell - Nice job! The 2-B came with Sylvania or RCA tubes when new. By the way, Zenith didn't make tubes, and all Zenith branded tubes were made by Sylvania. V2 can be problematic. The 6U8(A) is marginal on gain, and as it ages the 18.0 MHz crystal will sometimes fail to oscillate. The oscillator circuit is a little different in that it operates with fundamental crystals below 18 MHz, and 3rd overtone crystals from 18 MHz and up, with no switching. Anyway, the 18.0 MHz crystal is a 3rd overtone, and seems to be on the edge in more ways than one. Changing tube to a 6EA8, with its higher gain, will make this circuit more reliable. Quite a few 18.0 MHz crystals have been replaced over the years, when a simple tube change would usually fix the old one. The 8BN8 is correct also. The very first 2-A's had a 6BN8 here, but at s/n 1000, it was changed to an 8BN8 for hum reduction. There is an article at www.wb4hfn.com explaining the mechanism involved. You're off to a good start! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com Darrell Bellerive wrote: Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- When I completed my first radio restoration project, an Heathkit GR-81, and announced that my next project would be a Drake 2-B receiver, a few people asked me to post my progress to the mailing list. I will cross post to both the Drake (drakelist@zerobeat.net) and Glowbugs ([EMAIL PROTECTED]) lists. I will also include VA7TO 2-B: in the subject for those who would like to filter messages. -- Submissions:drakelist@zerobeat.net 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] VA7TO 2-B: Drake 2-B Restoration Project Part 1
Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- Garey, Thanks for the tip on the 6EA8 at V-2. From what I read on the web it looks like a direct replacement. Just plug it in. Am I correct? I have four good 6EA8's. Testing them on my Mercury Model 990 tube tester show the following emission levels: ProComm (Gt Britain) Triode 81 Pentode 81 HitRay (Japan) Triode 80 Pentode 78 Phillips Triode 79 Pentode 77 RCA Triode 76 Pentode 70 The tube tester good range is from 50 to 100. From your message it looks like the oscillator triode is the problem with the 6U8 and not the pentode (1st mixer) section. Which of the above tubes would you use and why? 73, Darrell VA7TO On Wednesday 23 July 2008 20:07, Garey Barrell wrote: The 2-B came with Sylvania or RCA tubes when new. By the way, Zenith didn't make tubes, and all Zenith branded tubes were made by Sylvania. V2 can be problematic. The 6U8(A) is marginal on gain, and as it ages the 18.0 MHz crystal will sometimes fail to oscillate. The oscillator circuit is a little different in that it operates with fundamental crystals below 18 MHz, and 3rd overtone crystals from 18 MHz and up, with no switching. Anyway, the 18.0 MHz crystal is a 3rd overtone, and seems to be on the edge in more ways than one. Changing tube to a 6EA8, with its higher gain, will make this circuit more reliable. Quite a few 18.0 MHz crystals have been replaced over the years, when a simple tube change would usually fix the old one. The 8BN8 is correct also. The very first 2-A's had a 6BN8 here, but at s/n 1000, it was changed to an 8BN8 for hum reduction. There is an article at www.wb4hfn.com explaining the mechanism involved. You're off to a good start! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 4-B, C-Line TR-4/C Service Supplement CDs www.k4oah.com -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada -- Submissions:drakelist@zerobeat.net 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] VA7TO 2-B: Drake 2-B Restoration Project Part 1
Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- Don, You will love the 2B/2BQ. It is a superb receiver. Mine is serial number 5735 so your receiver would be about 5 months newer than mine according to the chart at http://www.wb4hfn.com/DRAKE/DrakeSNDatabase-P1.htm 73, Darrell VA7TO On Wednesday 23 July 2008 19:40, Don Cunningham wrote: Don Cunningham [EMAIL PROTECTED] made an utterance to the drakelist gang -- Darrell, I will be joining you on that journey soon. I just got my 2B/2BQ in this evening (s/n 10040) and it looks to be in nice, unrestored condition. I have always wanted one of these, and looks like I got a fairly clean chassis even! Just a few suspect places from what I can see with the cover on. More later as the project progresses, but it may well be fall/winter with all the gardening and summer activities, hi. Keep us posted, Darrell!! Now, looking for the 2NT to go with it . 73, Don, WB5HAK -- Submissions:drakelist@zerobeat.net 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 -- -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada -- Submissions:drakelist@zerobeat.net 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] VA7TO 2-B: Drake 2B Project Part 1
Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- After reading a few articles on restoration, my 2B project is not a restoration that will include disassembling the entire radio or even a rejuvenation that includes painting. Perhaps calling it a tune-up is more apropos. 73, Darrell VA7TO On Wednesday 23 July 2008 18:53, Darrell Bellerive wrote: Darrell Bellerive [EMAIL PROTECTED] made an utterance to the drakelist gang -- When I completed my first radio restoration project, an Heathkit GR-81, and announced that my next project would be a Drake 2-B receiver, a few people asked me to post my progress to the mailing list. I will cross post to both the Drake (drakelist@zerobeat.net) and Glowbugs ([EMAIL PROTECTED]) lists. I will also include VA7TO 2-B: in the subject for those who would like to filter messages. -- Darrell Bellerive Amateur Radio Stations VA7TO and VE7CLA Grand Forks, British Columbia, Canada -- Submissions:drakelist@zerobeat.net 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 --
