W0THI
My friend Ken lives about 40 minutes away, on the north side of Terre Haute. His day gig is Director of Engineering for some local FM radio stations, so he knows his way around RF. And, he has a pretty nice HF shack of his own. I asked him about a week ago if I could bring my new radio up to his house to test it out. We arranged to do that this evening.
So, after work, I headed up to his place. His wife works the evening shift, so it was just he and I - and his friendly canine companion Candy, who greeted me in the driveway with a wag and a smile. He showed me around the house, and showed me the antenna farm outside (a nice tower with a couple beams on it, a G5RV, a longwire for NVIS, a delta loop, a sloper for 80 meters, and probably a couple other things I missed in the twilight). We then headed inside.
He started off by showing me his SDR setup that he uses for his HF work. He modified an older Kenwood TS-140 to get an IF sample out of it, and then he got a guy to build an SDR board to work off of the IF. We played around with that a bit and listened around.
Warming up the tubes
He scratched his head a bit looking for a place to plug in the radio - and then he unplugged his dedicated antenna analyzer and plugged my radio instead. That way, we could switch between his radio and mine easily by just turning a knob.
I plugged in my radio, turned it on, and turned on the heaters for the tubes. We started by listening. He tends to hang out on 7.200 in the evenings, so we started there. He used his radio to make sure there was a conversation going on on that frequency, and then he switched the antenna switch over to my radio. I set the mode switch for LSB, set the band for 7 MHz, and turned the VFO until it read 200 on the LSB mark. And I was hearing the same conversation. This was the first voice that I heard coming out of my new (old) radio - and it sounded good. Ken remarked on how good of a receiver it was. And it was apparently really well aligned, as my frequency was dead-on with the frequency on Ken's radio.
We found W1AW/7 (the ARRL station), operating from Washington state - and we heard people from all over the country contacting them as they try to get their "Worked W1AW in All States" achievement. It was thrilling to hear so many people from so many places all on one frequency.
Then, it was time to see how much power it would transmit. We found a dead spot on the band; Ken started by hooking his antenna analyzer back up and tuning the antenna for that frequency, and then we hooked my radio back up. I followed the tuning procedure prescribed in the manual:
- Set the plate control in the middle of the desired band, set the mode switch to LSB or USB, and set the carrier control to "something above zero" - I think I had it set at about 4. Set the meter to IP (plate current), and flip the standby switch to Send. Check the plate current on the meter - it should be 60 ma. It was reading about 75 ma; a quick adjustment of the "bias" pot on the side of the radio brought it back down. Flip the standby switch back to Receive.
- Set the meter control to ALC and set the mode to TUN (which greatly reduces the power output). Flip the standby switch to Send and adjust the Drive control for maximum meter deflection. Flip the switch back to Receive.
- Turn the meter back to IP and flip the standby switch to Send. Adjust the Plate control for minimum plate current (this is known as "dipping the plate"). Flip the standby switch back to Receive.
- Turn the meter switch to RF, turn the mode switch to CW (for full power output), and flip the standby switch to Send. Quickly adjust the Plate and Load controls for maximum meter deflection (indicating maximum power output).
This took probably a minute, as I was doing one step at a time as I followed the manual. But, when we got to the last step, Ken said "there we go". While I was watching the small meter on the radio, he was watching a larger wattmeter in his shack. My radio was putting out about 120 watts on 40 meters.
We did the same thing on 20 meters; again, about 120 watts. The tuning procedure went a little quicker this time, as I knew which knobs to twist. (I kept getting the Drive and Load knobs confused the first time around.) This will become a commonplace procedure with this radio, and it will probably get to the point where it takes 5-10 seconds instead of a minute.
About this time I mentioned that the radio had a dedicated WWV mode, which can be used for calibration. Since WWV transmits AM at 10.000 MHz, it's a great reference for checking the alignment of the receiver. I pushed the WWV button, and we listened to it for awhile.
80 meters brings questions
Next, Ken suggested trying the 80 meter band. This is where I ran into two problems.
First, I couldn't actually hear any conversations on the 80 meter band. By comparing his radio with mine, it looked like my radio was about 66 KHz high on its frequency reading. We found a couple CW stations, but I couldn't actually pull in any voice signals. This was quite concerning to me, and we spent 10 or 15 minutes trying different things to figure it out. I even turned on the 25 KHz calibrator signal, which acted really weirdly - I was hearing "early echoes" of the signal at about 8 KHz below each 25 KHz boundary.
And then Ken asked me: It is still in WWV mode or something? I smacked my forehead; I had left the WWV button pushed in. I turned it off, adjusted the VFO to an area where we had heard a conversation earlier - and there it was. I laughed, and said I will probably do this 2 or 3 more times before I remember to turn off WWV mode.
Once again, Ken unhooked my radio, found a dead spot on the 80 meter band, tuned his antenna to it (within reason - it was still at about a 1.4:1 SWR), and hooked my radio back up.
He excused himself (for a bio break) and I proceeded to try to tune up my radio. I got to step two (adjusting the Drive control) when I ran into a problem.
If you read my second post, you remember my statements about the "dirtiness" of the the Drive control which I attributed to a bad antenna connection. Well, I encountered it again. This time, I knew it wasn't the antenna connection - it was a problem in my radio. If I pushed on the knob or tapped on the case, I could get the meter to move - otherwise, it was undeflected. When Ken came back, I mentioned this to him. He asked me a number of questions about the radio; I responded by taking off the cover so he could see.
At first, we thought that the problem might be in the high voltage section, since the Drive shaft extends into that area. But then Ken said "let's try poking around in the front of the radio, where we can see". He got a plastic pen and started tapping on the three air-variable capacitors linked to the drive shaft. Two of them seemed fine. However, whenever he poked and prodded the frontmost capacitor, it clearly affected the received signal. He said "I think you have a cold solder joint between this capacitor and the board." That makes good sense to me as well; a cold solder joint is a poor physical connection, and at RF frequencies it will certainly make itself known.
To my knowledge, the way to fix a cold solder joint is to find it, heat it up, remove the old solder, clean the area, apply some flux, and re-solder it right. Probably not a huge deal, since I learned about the benefits of flux when I decided to do some rewiring on my electric bass.
However: I do not yet know how to get to the bottom of the RF board. The Service Manual has a lot of great information, but it doesn't include that. It does say to work quickly and use the least heat necessary to perform the work; too much heat can lift the traces from the PC board.
I did notice that the linkage between the Drive shaft and the capacitor is a little misaligned; the chain is stretched a little tight because of it. It's possible that, over time, this could have weakened the solder connection between the capacitor and the board, due to the chain providing some extra upward/sideways force on the front edge of the capacitor.
In any case, I was a little disappointed to find that there was a slight problem with the radio. It does seem to only affect 80 meters; we were still able to tune up the transmitter and put out about 100 watts on 80.
My antenna tuner
I also bought a MFJ-949E antenna tuner via the eHam.net classifieds. It is a 300-watt tuner with a built-in dummy load. It showed up today before I headed up to Ken's; I took its cover off to find that it was a fairly simply T-match tuner with a couple variable capacitors and a variable inductor.
I hooked this in to the mix while we were working on 80 meters. Ken bypassed his antenna tuner so that I could use mine. It seems that the meters in my tuner might need some adjustment; thankfully there are 4 adjustment pots specificallly for that purpose. Using my tuner (and its built-in dummy load) we were able to get the 100 watts output on 80 meters (as noted above). I'll leave meter adjustment for a later exercise.
After all, I still don't have an antenna at my house. Or a microphone. But the radio works. Mostly. I'll have to see if I can figure out how to fix the cold solder joint in the next few days.
So, thanks to Ken (W0THI) for the loan of his shack for a couple hours. I had fun catching up with him, playing with my radio, listening to his gear, rubbing his dog's belly, and laughing along with him at the conversation on 7.200. He even fired up his amp and jumped into the conversation - at 1200 watts.
Back home
Once back home, I was talking to Barb about the evening, including a description of Ken's antenna farm. She asked me, "so what sort of antenna does this thing need?" I said that it would be best served by stringing a wire between two of our trees, at about 30 or 35 feet off the ground.
Up until now, she has said "I blame Keith" anytime I acquired a bit of radio hardware. Now, with the concept of a wire strung over the house between two trees, she said "well, now I blame Ken." :)
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