Re: [Drakelist] My TR-7 restore and tantalum caps
Hello list! I have a newly required TR-7, S/N 3857 with remote VFO and PS S/N 5479. I will no doubt have some questions as I go forward with its restoration repair. Are there any documents that compile or list the "must do" vs. "should do" vs. "very nice to do" upgrades/changes and modifications for the TR-7? Or should I just try to search all the posts for the info, like newer board versions etc.? I know there are a lot of very capable people on here that have done all this already so I do not want to try to "re-invent the wheel". RE: TANTALUM CAPs I also have 3- Racal 6790GMs. They are literally loaded with tantalums with few electrolytics on the boards other than the PS. I have had some tantalums explode also leaving a black/dark gray deposit on everything around them. It stains and is hard to clean!! What I have found is that if you observe a small dark spot that appears to penetrate the outer shell and resembles a small volcano crater no larger than a pin point or a little larger, CHANGE THE CAP. IF IT HAS THE BLACK SPOT AND HASN'T YET FAILED IN THE EXPLOSIVE MODE OR HASN'T ALREADY FAILED DOSSIALY INTACT, IT WILL FAIL! I have changed out over a 100 tantalums in these radios so far. To change one or not is a personal call but the cleanup after one pops is a PITA. It can also damage components ahead of it if it shorts to ground and the supply is stiff enough. At least look them over closely for the spots. They don't always have the spots but many times they will have them at some time before failure. Of course the lack of spots doesn't mean they won't fail but a spot is a sure sign of impending failure at some point. Thanks in advance for any suggestions you folks have for the TR-7. 73, Walt KR4HV kr...@numail.org ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] My TR-7 restore and tantalum caps
On Sat, 30 Jun 2012 13:35:41 -0400, KR4HV wrote: >Are there any documents that compile or list the "must do" vs. "should do" >vs. "very nice to do" upgrades/changes and modifications for the TR-7? Yes and no. The list archive can be your friend, most mods have been discussed pretty thoroughly. Web site wb4hfn.com has some excellent articles, and also look for the GW4ALG and PA0CMU mods pages (but don't go nuts with mods). And, of course, the Drakelist home page. If there's a specific mod that strikes your fancy, ask about it. My page on the 2nd IF/Audio board is a good read, although still a work in progress: http://radiojim.exofire.net/pages/TR7_2IFA.html Do re-seat all the plug-in cards. Do replace the filter electrolytic on the power supply board. Do the 10V adjustment, frequency, and AGC (if the 10V was very far off) adjustments in the service manual, or if nothing else, do the fixed passband adjusments. If the PTO lamp has ever been replaced, you can just about guarantee that one or more of those pots was bumped. Upgrading them to 10-turn trimmers is a worthwhile mod. There's been some debate about ALC mods lately, but I don't seem to have the ALC overshoot that others have seen. I need to get back on that Do put a fan on the back, pulling air out, if you don't have one already. If you're a CW op, do look at K8AC's fine tuning of the CW waveshape. K8AC and I have both done some recent work in the S-Meter area, but we may both arguably just have too much time on our hands... Don't use the published Drake allband transmit mod, there's a better way. Again, check list the archives (and the Drakelist Online Forum). Don't use a preamplified mic. Don't set the ALC adjustment (bottom side of rig) for more than 150 Watts CW output, some ops prefer less. Don't freak if the RX appears to be dead, there's an internal jumper that will have been cut if the rig was slaved with an R-7 in a previous life. Remember that this rig has no speech processing built in, so average power on SSB will appear lower than on modern rigs - use the ALC light to determine proper drive level. >Or should I just try to search all the posts for the info, like newer board >versions etc.? Yes. There's lots of stuff out there about mixers, Schottky diodes, DDS VFOs, DSP, whatever. Some of it good, some debatable, some bad or not worthwhile. You can spend hours sniffing it all out (I did :) ). Google (or Ixquick, if you're paranoid) can be your friend. Also recommended is the DrakeRadio Yahoo group. There's not much in the way of newer board versions that offer any real advantage that I know of, and at least one ham that I know of has found the version 1 2nd IF/Audio board to be preferable. Have fun! 73 -Jim NU0C -- Theres something out of place lets go and poke it with a stick. The Doctor (Amys Choice episode) ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Xtals
Hi Group I am looking to replace out of spec xtals in my Drake R4C receiver. One's listed are 4-9 Khz off frequency. The * xtals are for 160M & 10M are more a priority. Contact me off list @ wmarv...@charter.net Wanted: 1.5 Mhz 12.6 Mhz* 3.0 Mhz 14.1 Mhz 9.5 Mhz 20.1 Mhz 10.0 Mhz 21.1 Mhz 11.5 Mhz 22.6 Mhz 28.0 Mhz 39.1 Mhz* 28.5 Mhz 39.6 Mhz* Best Bill KB9IV ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] R4C Xtals
For the most part I have found the xtals...thanks Doug! Best 4th to All Bill KB9IV___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] For Sale listing
Please advise if Drake items for sale can be listed on this site. Tnx de Ed, VE-3-FTO p...@sympatico.ca ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] My T4X project- questions
This is my first project resurrecting a dead T4x. So far, I have put the new capacitors in the Ac-4, but not tested yet. I have disassembled the front panel and tried to clean off what I initially perceived to be smoke tar from the front panel. Now, I am not so sure. I may be attacking some clear-coat Drake put over the original paint on the front panel which has yellowed with age. I am through it in many places, and the paint is much brighter underneath, as is the aluminum. So, in for a penny, in for a pound, I will take off the rest of whatever it is. The question is whether I should put a clear-coat back on. Can someone confirm that Drake used a clear lacquer or varnish over their paint? Next, I am going to do the 6146 final conversion. The plate choke has been burned, and maybe soldered upon. (turns have insulation burned off, and a few shorted) I can laboriously rewind the old form with #29 wire which I have in my junk box. (I measured .0115 dia. AWG 29 is .0113) or, I have sourced a substitute solenoid from SSN. It is the same diameter, and the wire is either #29 or 28 gauge. I can take care of the mounting problems. The new winding is about 9/64 longer than the old one, and the cage height will accommodate the length. Does anyone foresee any problems with a little extra inductance in the plate choke? I could also unwind turns to get back to the original length of solenoid. I have tested it with my MFJ 259 up to 160 MHz and did not see any series resonances, and the wire size will handle the plate current. I am considering how to clean the rust pitted chassis. I have used my dremel rust stripper, gently, and I get a nice shiny metal with no pits and gunk. Unfortunately, it will not reach everywhere. I have not been able to convince myself to immerse it in anything. I did read about glass bead blasting. I have the air compressor capacity, and could make a small chamber to blast the chassis. Question: What parts should be removed first? I am thinking the PTO, meter, and the compression trimmers in the transmit chain. The one under chassis will be protected with tape on the inside of the chassis, as will the tube sockets, and slugs in transformers and any pots. (Seal with tape) What have I overlooked? Should I remove the variable tuning capacitors before beginning? OK... my first post, though I have been lurking here a while. 73 NY0Y Raleigh ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] 10 meters for the Drake L7
Hello everyone, new to the list. I'd like to know if anyone has or knows where to get an authorized bulletin from Drake outlining the procedure for enabling 10 meters on the L7 amplifier. I've seen a "blurb" about it on the Internet but nothing that seems to be Drake authorized. Although I have done the modification as shown in the blurb I am not liking the input swr results I am getting on 15 and 10 meters now. On 160-20m my amp has a dead flat input swr, but not on 15 and 10. I have questions. If no bulletins had been issued and anyone has done this mod with greater success than I, please let me know. Thanks, 73 Lou W1QJ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] 10 meters for the Drake L7
Lou, Well, "it depends". There are at least three ways the L7 bandswich was locked out from 10 meters; I assume you found the way to undo yours. For the L7s I've serviced, I found two different results with no consistent explanation for the differences. In one case, you do the mod by adding the two 68 pf caps, etc. and then retune the input coil per the instructions. In the other case, adding the 68 pf caps is not necessary, and the input coil doesn't always need to be adjusted. Both procedures seem to work, depending... 73, Evan, K9SQG -Original Message- From: Gudguyham To: drakelist Sent: Sun, Jul 1, 2012 12:01 am Subject: [Drakelist] 10 meters for the Drake L7 Hello everyone, new to the list. I'd like to know if anyone has or knows where to get an authorized bulletin from Drake outlining the procedure for enabling 10 meters on the L7 amplifier. I've seen a "blurb" about it on the Internet but nothing that seems to be Drake authorized. Although I have done the modification as shown in the blurb I am not liking the input swr results I am getting on 15 and 10 meters now. On 160-20m my amp has a dead flat input swr, but not on 15 and 10. I have questions. If no bulletins had been issued and anyone has done this mod with greater success than I, please let me know. Thanks, 73 Lou W1QJ ___ 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
