FWIW I found shorted caps in the Drake receiver that I inherited.
An R-8 if I recall correctly. It's packed up and I haven't touched it in years. I replaced it with a Racal RA-6790 and now it's developed problems too
After Googling I think I found the retrofit lights that are in the SPR-4 (but won't know for sure till mid-week when I get it). They might be these designs -
http://www.radiolabworks.com/products/4linelamps/4linelamp.html
However, after looking at a whole lot of pics of this radio and others that have the original blue, they sure don't look like the right color to me.
In any case - more to come ...
Personally I think that the before modification photo is much more readable then the after photo, I thought I'd throw my in views on it just in case.
Agree.
I'd go as far to say that blue LEDs are a visual cancer on this planet IMHO. I rather like an incandescent lamp.
I agree with everybody, the blue LEDs are weird and make the scales harder to see. I really like the original light though.
It looks as if someone has been in there before, some very dodgy looking joints there. The 4th and 5th crystals don't look to be fully seated in their sockets either. Apart from that I like the way that each section has its own pcb, makes it easier to a full recap etc board by board.
Interesting noise blanker you got there
Looks pretty good inside. The thing will be easy to debug at least as each bit of the signal chain is separate.
@Xrunner, very good indeed so far, looking forward to seeing the completed item and seeing how it performs. The 10uF tant, replaced because its a "bastard tant" or because it is duff?
nice
Interesting schematic. Dead simple filter. Watch those early dual gate MOSFETs though. They have no protection diodes. Look at them wrong and they're gone!
Good fix, all working nicely now?
Nice job
Also nice QSL card collection hiding there. Still waiting for my first batch. Takes bloody forever via RSGB and I’m not doing eQSL or LOTW. I’ve got one damn QSL card so far sent direct.
Good fix, all working nicely now?
Apparently it's working OK Specmaster, I lashed up a Signalink to it and the computer. It's receiving a weather fax from NOAA station NMG out of New Orleans on 8.504 MHz pic attached.Nice job
Also nice QSL card collection hiding there. Still waiting for my first batch. Takes bloody forever via RSGB and I’m not doing eQSL or LOTW. I’ve got one damn QSL card so far sent direct.
Yea direct QSL cards take a long time and can cost money too. I've also lost quite a few in the mail system of several countries such as the likes of Venezuala and several African countries (you know who you are). But it's still cool to get a "real" QSL from another country. Hope to work you some day so I can send you one!
Here's another pic of more on the wall. Also a letter from your neck of the woods with a QSL card in it from some DXpedition I worked. I guess I should open it this evening LOL.
. I wonder if they get opened as the old “send a dollar” thing is still well known. Fingers crossed we’ll catch a QSO. Probably not until I get a new house and a beam
So its almost completed, well done so far. It looks to be almost new now and fits right in with your bench
That's a pretty nice bit of work that is actually. I've seen them before on YT videos usually but not up close like that.
I'm pretty lazy and cheap with those things though. If they haven't leaked I usually snip the terminals off the bottom and chuck new radial ones under the chassis
I had an early SPR-4, S/N 304 as I recall. after a few months, dial lights kept burning out. Found out the zener diode in the voltage regulator was open circuit and the regulator was putting about 18 volts on the 12 V line. Analyzed the circuit and found there was more than 1 watt power dissipated in the zener, which looked like a 400 mW size. Changed the 47 ohm resistor supplying the zener with a higher value and never had any more trouble.
So here she is - the fully restored Drake SPR-4 in it's rightful place on my radio desk.
Now, back to Ebay!