hallicrafters SR-2000 time delay relay?

Discussion in '"Boat Anchor" & Classic Equipment' started by WA6MHZ, May 20, 2013.

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  1. N2EY

    N2EY XML Subscriber QRZ Page

    I'm not sure it's the right one. I will download the manual and check.

    EDIT!! I checked the manual - you do NOT want a 115NO90T!!

    The correct part is a 12NO90T. The thermal relay runs off the 12.6 volt heater circuit, not 115!!

    You can also use a 12NO120T, 12NO150T or 12NO180T - they just have longer delays.

    They are all over ebay; the trick is to wait for one that is under $10. They can also be found at hamfests and in old Tektronix tube 'scopes.

    Did you read the article in QST (May, 1995, page 84)?
    Last edited: May 22, 2013
  2. N2EY

    N2EY XML Subscriber QRZ Page

    OK, fine. When you say "900 watts out", what mode was that? Did you use the stock power supply?

    I'm just curious. The tubes can certainly do that kind of power on CW!
  3. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    Thanks for the Correction! Those are probably a little more rare than the 115V ones. But I will begin to hunt the relay.
    I built a timer circuitry for my 6M 4CX250B kilowatt using a variety of 555 timers and logic circuitry. It would run the PS for 2 minutes before HV was allowed to be applied, and then would run the fans for 2 minutes after the amp was turned off. So I can do it with 555 times and RS Flipflops. I probably will design that circuit while waiting for the Relay to show up somewhere. That can be put under the chassis so the PS will appear stock. I copied down the number and will begin the search. Just hope I don't hafta pay $50 for it. I would be TICKLED to pay $10-$20 for it!
  4. N2EY

    N2EY XML Subscriber QRZ Page

    It should be possible to find a suitable one for less than the price of an SS replacement. They are not rare! Note that in the control circuits you are switching AC, so you need a relay anyway.

    One possible work-around is to use an Amperite timer with a 6 volt heater, and a series resistor/voltage divider to drop the 12 volts to 6. A lot less work and headaches, plus easily reversed. 6NO90T, 6NO120T, 6NO150T, 6NO180T are all suitable with dropping resistor in the heater lead.

    Another trick is to use a 26 or 115 volt heater version and a small transformer to step up the heater voltage.


    One comment about eBay:

    I looked through the for-sale items under "amperite delay" and was astonished at the prices. I thought "I'M SITTIN' ON A GOLD MINE!!!"

    But then I looked at the "sold" listings - and found the actual selling prices were much, much lower. Usually under $10.

    Always keep in mind that the only price that matters is what someone actually pays. I may think my BC-342N is worth $1000, but until somebody actually ponies up the cash, my thought is just a thought.
    Last edited: May 22, 2013
  5. WD0GOF

    WD0GOF Ham Member QRZ Page

    Every thing you ever wanted to know about the SR-2000 can be found at http://k9axn.com/_mgxroot/page_10759.html . Jim is the leading technical expert on the SR-2000. He suggests the 90 second "12no90t" (12 volt heater, normaly open, 90 second, thermal delay) relay, sometimes refered to as a ballast tube, be replaced with a "12no120t". This will insure the cathode of the tube is at proper temp before HV can be applied. You could build a SS timer to replace the thermal relay, but you would probable have more $ in parts than a new original part will cost. The part is not rare, yet it is costly. I have been repairing the SR series rigs on and off since '78, I have never seen one fail in service. The only they "fail" is thru misshandeling. If you go with the original part it will most likely be a one time purchase.

    73, Walt
  6. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    That's what I am thinking now, as RF Parts does NOT stock the 12V unit. Should be able to put a series resistor in with the 12V to get down to 6. I found some OCTAL socket models. On Ebay, all I see even close is the 115V model. Now, I could get a 12V to 115V transformer and hook it backwards to the filament line, and use that. Not sure what I am going to do, but I SURE can't fire this thing off without the relay circuit. They are making me work on COMPANY stuff today. They want me to make up for the 10 days off!
  7. N2EY

    N2EY XML Subscriber QRZ Page

    I agree with that replacement 100%. Even more time (12NO150T, 12NO180T) wouldn't hurt a thing.

    btw, a "ballast" or "ballast tube" is a completely different thing. The confusion probably results from both ballast tubes and time delay relays being made by Amperite in tube-type glass envelopes.

    Very good advice IMHO.

    I have been using the Amperite relays for about that long and never a problem. And the ones I have were used when I got them.
  8. WD0GOF

    WD0GOF Ham Member QRZ Page

    Be aware!!! If a dropping resistor is used you must seperate pins 1 and 3. Pin 3 needs the full 12 vac. That said, N2EY's suggestion of using a 6NOXXX is a very good option.
  9. N2EY

    N2EY XML Subscriber QRZ Page

    The power supply chassis is pretty crowded. You could make an adapter that has 9 pins on the bottom and a octal on top, but I don't know if there's enough room for an octal there.


    You're not looking, then. There are two 26NO120T up now - one is $4.50 plus $2.25 shipping, the other $9.99 with shipping. Of course they have 26 volt heaters rather than 12 volt, so you'd need a little transformer to boost the voltage.

    That's what I said a couple of posts ago. More a question of space than anything else.

    Be patient. Keep watching the bay. Do some googling.

    And you can fire it up without the delay IF you wire in a switch and IF you remember to allow warmup time.
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I had an SR-2000 also back in the early 1970s and it would deliver 1kW PEP output power, no problem, SSB or CW. It would even do that for a steady carrier on tune-up, but probably not for long, maybe several seconds.

    One potential "issue" is the rig is old enough that back then line voltage was typically 117/234Vrms. Now, it's higher, everywhere. My line voltage at home runs 245Vrms all the time, slightly higher in the hottest WX summer months when everyone's running A/C and the utility actually pumps the voltage up a little bit higher to make up for the huge demand.

    Whether this may cause any "overvoltage" problems in operation, I'm not sure, since I haven't used an SR-2000 in many years. But you might check the HV filter caps for potential OV issues, and maybe the heater voltage on the 8122s to be sure it's not too high. They're still available, but not cheap.
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