Monday, May 25, 2020

Tidying Up Loose Ends

Governor Hair Gell
I was wrapped up over the last couple of weeks with how to occupy myself during the house arrest that Governor Hair Gel (the stupidest Democrat in California) and the Los Angeles County Crypt Keeper - "Dr" Barbara Ferrer - has imposed on California and Los Angeles.

"Dr" Barbara "Crypt Keeper" Ferrer
Yeah, I know I don't live in that Dem shit hole that is Los Angeles (thank you, God!) and I am not in Hell -- but I can stand on my tippy toes and see it from my QTH. But enough of politics (sort of). Because the COVID-19 farce has conspired to cause virtually every aspect of our lives to be cancelled, we members of the Zuni Loop MEF group have decided to not trek to the mountains and do Field Day. Actually, Field Day will not be the get-together it always is as alternate plans are being concocted to accommodate social distancing and the like. (I just hate that term but understand it's necessity.)

Anyway, I prattle. I decided to resume kit building and reached into my stockroom to pick a thing or two out of my inventory.

Me emerging from the treasure trove with a couple of items

Long story short, I built two 30 meter kits: one of Diz's Kits and Parts 5-Watter and the remaining Midway ME-30+ I got several weeks ago. Both went smoothly at first but the road had some "bumps" and I had to iron out some tools and techniques. I will write up one of the "bumps" here and will write up the other "bump" and the 5-Watter build in a subsequent post.

Let's cover the Midway ME-30+ kit first. I won't do the full review because, let's face it, it is basically identical to the ME-80+ kit in assembly and materials except for the band differences and it went together quite well. I still love these little radios and -- years on from my original cruise through Dave Benson's kits -- I now understand the circuit and marvel how neat it really is. The VFO is rock stable and the receiver is incredibly sensitive. Both the ME-80+ and ME-30+ hear down to -130 dBm.

However, in completing the ME-30+ and being generally happy with the build, I was somewhat apprehensive because the most that could be coaxed out of it was just a smidge over a half a watt. Going back over the rig, I noted that I had populated the BPF middle cap with a 68 pF value instead of a 680 pF cap. (That is, "680" does NOT mean 680 pF, it means 68 pF.)

Live and [re]learn, I guess. That got me up to just over 1 watt. So as I was trouble shooting this, I started a letter to to the Midway Express owner, Rick Choy, about this matter:


Sorry to intrude on your Memorial Day holiday -- and this need only be addressed in your convenience -- but I have some questions re your 30m kit I just recently finished, to wit, is it performing to spec? I believe it is; just wanted to confirm. Here are the facts:

(1) Basically, there were no problems with the build/checkout but I could only manage to get just over 1 watt out of it when done.

(2) Went back through and checked ALL components and found none misplaced nor any solder bridges, bad joints, etc.

(3) I checked most of the voltages versus the schematic -- specifically the XMIT chain -- and they were 100 percent.

(4) I checked the signal levels and the appeared normal.

(5) Specifically, I checked the signal at the base of Q6 and found that to be approx 2.5 Vpp.

(6) The output at the collector with the pot wide open was 27 Vpp or 1.8 watts (27^2/400).

(7) The output at the BNC with the pot wide open was 23.5 Vpp or 1.4 watts (23.5^2/400).

(8) I note that the BPF drops the signal almost 1/2 watt.

I wanted to see if this is normal because the ME-80+ I built had an output of more than 2 watts. Of course, that was 80m and this is 30m. Also, I have no heartburn about this because I will throttle this little radio back to 990 mW so I can work QRPp. Just checking. Screen shots below.



But, after I got to thinking about this, I realized I could do a comparison of the ME-80+ and the ME-30+ and see what's what. So the letter was not sent. Basically, what came up was the ME-30+ was not losing a lot into the BPF -- at least not as much as the ME-80+ was. Here is a comparison table of the results:

So, it appears that the ME-30+ is doing the best it can despite having more drive (2.4 Vpp versus 2.0 Vpp) which probably means that the Q6 in the rig is a little weak. Here are the traces for comparison.

ME-30+ Signals
ME-80+ Signals

So the bottom line is that these kits are fun to build and operate and they are small and have a "heft" to them so that you won't hesitate to take the radio with you to a local park or mountain top, etc. (Some of the these fragile "pocket" radios feel like they will fold up in a stiff breeze.) that's it for now. Next up, a man with two watches is never quite sure.

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