SR-2000 restore

Discussion in '"Boat Anchor" & Classic Equipment' started by WB3JIH, May 25, 2018.

ad: L-HROutlet
ad: l-rl
ad: MessiPaoloni-1
ad: Left-2
ad: Left-3
ad: L-MFJ
ad: Subscribe
ad: l-assoc
  1. WB3JIH

    WB3JIH Ham Member QRZ Page

    I know there's another thread going on regarding a SR-2000 restoration, but didn't want to hijack.

    Looking for advice. First, I've gone to all of the standard locations, BAMA, K9AXN, etc, and soaked up as much material as I can. I've got a couple of issues left, but making good progress. I have a good power supply, the radio is aligned, and I'm now working on the PA compartment.

    So, first question -- it looks like someone has been in the rig and done some extensive work. There are a lot of areas where translucent insulation has been strung over conductors, both component leads and in the tank circuit. Some was done well, others show evidence of leads cut off and new components just tacked to the old lead. I've got most of that worked back, but I'm having a tough time reverting things to stock as I have no idea what it was supposed to look like as OEM.

    Here's my greatest area of concern though -- the PA compartment. So far, I've identified that the antenna relay isn't functioning correctly -- and it's causing arcing, low receive, hi SWR, etc. As anyone who has worked on one, it's impossible to access unless you disassemble half of the tank circuit (which I've done.)

    First, any suggested source for replacement? It appears to be a standard 120 vac coil with three elements. What's in there is an open frame type, so wondering if there's a better "modern equivalent."

    Second, and this troubles me more, is that the tank coil form appears to have been liquefied as some point. A prior owner put some spaghetti on it, but the coils are now clearly out of spacing and the form has made a real mess. The rig does seem to transmit on 40 meters, but haven't been able to get anything else.

    Here's what I'm talking about:
    SR-2000 tank1.jpg
    sr-2000 tank2.jpg

    So, I'm not averse to replacing this. I saw some pictures of this on K9AXNs site, but nothing about how to address it. The older Swan gear I've rebuilt had a similar problem with the plastic coil form until they went to a ceramic one. I hate to think how this rig must have been abused to cause that kind of damage on the coil form...

    Anyways -- looking for some advice.

    Thanks!

    Jeff
     
    KK4CUL likes this.
  2. KK6IYM

    KK6IYM Ham Member QRZ Page

    I have an HT 44 that had a similar problem. I wound a new coil, which didn't turn out to be all that hard to do. I used silver wire, but it was jewelry wire and had a very thin plastic coating to protect from tarnish. This made soldering a little more difficult than without the coating. It did seem to be stiffer than some other wire, which I think helped. The transmitter worked very well after it had been restored and the coil replaced.

    Norm
     

    Attached Files:

    • 4.jpg
      4.jpg
      File size:
      126.1 KB
      Views:
      61
    • 51.jpg
      51.jpg
      File size:
      55.1 KB
      Views:
      66
    • 60.jpg
      60.jpg
      File size:
      51.4 KB
      Views:
      72
    • 61.jpg
      61.jpg
      File size:
      155.5 KB
      Views:
      65
    • 62.jpg
      62.jpg
      File size:
      158.3 KB
      Views:
      65
    • 63.jpg
      63.jpg
      File size:
      126.6 KB
      Views:
      63
    K9AXN and KD2ACO like this.
  3. KE0ZU

    KE0ZU Ham Member QRZ Page

    I did something similar a few years ago for a National amplifier.
     
  4. K9AXN

    K9AXN Ham Member QRZ Page

    Jeff,

    Looks to have been an attempt to go CB or just a lot of glue dumped into the coil.

    Long story short, the radio has apparently been found to be unstable and the person simply tried to tame it. The SR-2000 is absolutely stable when working properly. The radio was designed to operate at 2KW with a grudging 2200 Watt limit.

    We're in the process of writing the process to restore the final compartment to factory plus which will be placed on the web site because it's a bit lengthy. For now, the coil issue. Here is a coil that ha been straightened out and re-spaced with Teflon insulation stripped from #14 wire; weave it into the coil.

    http://k9axn.com/attachments/RESTORE_10_HOT_COIL.JPG

    The 10 Metre section has a tendency to run quite warm if the 8122's have been replaced with high bias tubes or the OP liked to pin the AALC meter in a contest --- will be addressed in the final compartment paper.

    Please send or provide close ups of the complete final cage top and bottom and the chassis top and bottom. Might make sense of the purpose of the mods.

    Regards Jim
     
  5. K9AXN

    K9AXN Ham Member QRZ Page

    Nice job. The HT44 is an extraordinarily well designed amp. One of the few that properly exploit sweep tubes.

    Regards Jim
     
  6. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Such a shame when people abuse gear like this.

    Good luck and enjoy it!
     
  7. WB3JIH

    WB3JIH Ham Member QRZ Page

    Thanks Jim and all.

    Well, I rolled a new tank coil today, so just need to epoxy it and reinstall.

    Jim - I didn't think to take pictures of what was there beforehand. It was definitely "not stock", so I did not provide it with any respect. :)

    It was mostly wire connecting every screw to a ground buss. There were also a half dozen doorknob capacitors in various spots throughout the cage; looks like the primary purpose was to provide multiple bypass points. A lot of work when a little bit of penetrox would have done the trick. I think you're right, whoever did this was trying everything they could think of to tame down the PA.

    Like I said, the good news is that I've got the rest of the radio functioning pretty well. It hears about as well as my SX-117. Transmit circuits are all in line, so now I just need to get the PA done. The plate choke shows signs of thermal abuse, but seems to have OK continuity.

    One of the 8122s was black from thermal damage. I managed to get a used one, so I have two RCAs of unknown vintage.

    The PA also has an additional trimmer cap mounted near the neutralizing tab, again, probably to get it stable on 11 meters.

    Frustrating...

    I'm keeping an eye on your site Jim. Let me know when you have the PA stuff posted.

    Jeff
     
  8. K9AXN

    K9AXN Ham Member QRZ Page

    Jeff,

    Received your photos and believe you need to get in shape to climb Mt Everest to tackle that project.

    The radio may be a build from scratch not restore. Would recommend looking for an SR-2000 without PS2000 that is restorable. Then you can see what has happened to that radio.

    We can help with that if your interested. Let me know.

    Good luck.

    Regard Jim
     
  9. WB3JIH

    WB3JIH Ham Member QRZ Page

    Jim -

    Not my first climb. Been up K2 with an SR-500 that was in far worse shape. I scratch built a CE100V that suffered similar indignities. I had to construct custom rotary switches for a GSB-100...You can see them all on my profile page.

    Don't mistake my gutting the final compartment with condition as found. The radio hears quite well on 40,20 and 15, and develops clean RF through the plate of the 12BY7. Its the PA section that is my primary obstacle at this point, along with identifying the mods that were made after the fact.

    I've mounted the recreated tank coil in the compartment and tapped it at the same windings as was on what was left of the original. It has the 1971 bandswitch modification, so your materials were useful in ensuring that was correct. I'm struggling a bit with the OEM physical layout of the 14awg interconnect wires, but I had to do the same thing with the rescued HXL-ONE linear I found that was converted for some unholy reason to 6 meters.

    If I could ask though - could you take a look at the photo I sent you of the preselector variable and tell me if the one section is salvageable? It looks like a trimmer screw is missing, but it may be nothing.

    Thanks...

    Jeff
     
  10. WB3JIH

    WB3JIH Ham Member QRZ Page

Share This Page

ad: GNOHF-1