Started doing the alignment on the SP-600 and found that the receiver was deaf it could barely hear a 1-2uv signal, and 3 uv wasn't much better. After doing some resistance checks through out the receiver I found pin 5, V1 was open should be around 16.5K. So I pulled the RF deck out again and found L7 192 uh choke was open not sure how this happened, so now I have a 65lb door stop unless I can find a reasonable replacement. I found a 200uh choke at Mouser to try hopefully it will work. Since its just a plate choke how critical is the value of this choke?

Not critical. It is meant to isolate the plate from RF. Just be sure the current handling and voltage spec is sufficient. I worry about modern parts because many times they are for low voltage circuits. My 600 had one of those plate chokes broken, but still connected, so I just glued the break with Krazy glue and it worked fine.

Norm

I agree with Norm, its not critical and the mouser part should be OK.

Cool thanks guys have my fingers cross that's it with the problems.

Anyone ever use a spectrum analyzer for alignment? It wouldn't be a modulated signal so I'm wondering how that might affect things?

you might be able to tune it up just using the receiver's input noise, if you have a way of knowing exactly where your corner frequencies are, or you would need a tracking generator.

Another way would be to use a sweep generator and log detector, like I did here.

Mike,
After reading through some of the archived post about sweeping the I.F. I 'll just stick with the procedures in the manual doesn't really sound worth the effort.

Update: I replaced the open RF choke with Mouser 807-1537-90J and I 'm glad to report all is good. After removing the RF deck for a second time to replace the RF choke I did a quick inspection of everything and reinstalled it. Upon power up there was a snap crackle pop sound, quickly turning off the power followed by a whiff of burnt component smell GREAT! no what?
So after waiting a day or so to cool down my temper the RF deck was removed for a third time. Inspection found one 33k resistor burned, and another looking a bit discolored I replaced the resistors, but there was still something wrong when measuring the resistance of the circuit. Using a magnifying glass I was able to find a blob of solder that was bridging between pins 5 and 4 V1, somehow when soldering the choke back in a blob of solder rolled off the back side of the tube socket pin and welded itself to pin 4 which is ground i.e. B+ to ground not good. Luckily the new choke was okay reinstalled the RF deck, applied power and the SP-600 came to life. Alignment went smooth everything went by the book the receiver is working real well I'm very pleased with its performance.

Congratulations!

I always hate it when the problem is me - as it increasingly is.

Thanks
Yes me too must be an age thing.

Glad this worked out for you. the alignment of my SP-600 stalled for a couple of reasons. Did you have problems aligning the higher frequency bands? (Every time I stick an alignment tool in there it seems to have a negative effect - even one I made out of an oak dowell).

Curious to hear - and what type of screwdriver did you use to get down into the turret?

I used a hollow plastic alignment tool that has a small metal screw driver blade stuffed in the end of it. The tool is around 9" long, had no real problems accessing the turret adjustment points, but did need a flash light from time to time to see where I was aiming though. Yes the higher bands can be very tricky, when one finds the peak removal of the alignment tool causes the peak to move off frequency. So what I did was to find a point above or below the peak so when the tool was removed the peak moved back to the alignment frequency point this takes a few tries, and a few cuss words to get it right.

Dave

Great, thank you - that's helpful.

Dave is quite right. If you shine a light into a hole other than the one you are working with, and look into a third hole, it makes it possible to easily see what you are aiming for with the alignment tool. It can be pretty frustrating otherwise. I have a small LED soldered on the end of two solid insulated #20 wires that I can fish into holes. A couple flashlight batteries completes the lighting device.

Norm

Good idea Norm I may try the LED trick you can get the light right down where one needs it.

Dave