Friday, October 5, 2012

Project Clean Up Part 1 Chapter 8

Chapter 8: "Walking in the Hollow State"


This is a continuation, the First part is Here,  a complete list is available under "Ham Radio Master links" on the sidebar.

Getting the power supply working, putting out good, well filtered voltage was relatively easy. The hard work was getting the radio itself QRV once again.
That's right, more problems.
Seeing that I was trying something crazy, like switching tubes, I decided that I would revert to the original two tubes, in their original sockets. Why tempt the smoke? It needed to stay in the caps this time, or money would be spent!
I put the two tubes in, confident in the knowledge that I have made QSOs with these tubes, tuned the Swan 100-MX to 3579ish, tuned the antenna on that frequency, switched antenna outlets, keyed down, and heard noise! Victory? Not quite.
 So I tried peaking the tank cap, no dice, then went investigating the tube sockets themselves again because I stopped getting any signal out when I jiggled the connection. I didn't notice anything immediately obvious, but Warmed some joints anyway, and made sure nothing was shorting anything out.





Then....


I packed up shop for the night, scowling at my fortunes.
No power, no nothing, just time for bed.
Suddenly, I had an idea!
What if one of the tubes was bad? Like the one that was still on the chassis when I smoked the radio the first time? Couldn't hurt to try right?
Sho' nuff, soon as I  switched tubes and gave it a minute to warm up, bam! power out. Then I went to bed.



 Time for the Finishing touches




I decided to button up the power supply. I clipped the primary to secondary connection to shorten the wires. The plan here was to mount the capacitors and surge resistor in the middle and the rectifier more or less on top of the secondary transformer.
More or less that's how it went.
Getting that bugger in there was tough! I had to cajole, caress, tweak and twitch over the course of two nites, but sure enough, it happened, and I was able to get that sucker in there!

Now it's time for a QSO!
That corresponds to ONE BLAZING WATT of RF on a dummy load.
On to the next project!

73,
DE KG4GVL TT-80 QRT

Thank you all for reading!

ps,
I will occasionally post followup articles to this series, and will keep a list of all the states I've worked and confirmed. My goal for this rig will be WAS or something. Look for me round about 3579KHz, in between all the digi stuff...

2 comments:

Steve "Snort Rosin" Smith WB6TNL said...

Sounds like much less chirp, in fact it's difficult to say if there is any at all now. I'd attribute that to the change to a bridge rectifier. Have you measured the D.C. B+ both key up and key down?

73.......Steve Smith WB6TNL

G. Brandon Hoyt said...

I've noticed the same thing Steve, definately seems to be less chirp now, and when I key down on a long K before flicking the tx to rx switch, the signal is a lot more stable. I will try to get a measurement tonight after work.