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Messages - k7rmj

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1
Antennas and Towers / Antenna Builders Guild
« on: April 08, 2018, 05:57:52 PM »
The attachment is a report I wrote a few years back. It is about an antenna that not many people hear about. And, it is certainly not stealth LOL. It has two legs that are 330 feet long. I hope you enjoy it.

73 DE K7RMJ  Frank

2
Antennas and Towers / Arkansas Antenna is COMPLETED
« on: June 22, 2017, 02:29:22 PM »
YAAY, It's up and it works. The roof-climber guys shoed up yesterday and we got the tower installed and the antenna up and working. It's been a long project but finally completed. We put the tower up first and bolted it to the platform. Then we installed the antenna on the mast and the mast on the tower. The fun part was figuring out which direction was south LOL. Nobody had a functioning compass, so we looked up my address on Google Maps and eyeballed the direction the ridge peak of the roof was pointing. Then to get a precision installation we used the TLAR method. (That Looks About Right). After all, that beam has a 60 degree beam width at the 6db points in the radiation pattern. Yup, I stayed up too late last night playing around on 20 meters. It was open up to about 1800 miles until sometime after midnight. I gave up around 11pm. Needless to say, I am a happy camper now.
73 DE K7RMJ  Frank

3
Antennas and Towers / Re: Arkansas Antenna
« on: June 18, 2017, 05:21:14 PM »
Here is some more of the "Rest of the Story". It is a bit long at 6 pages but I did manage to include a few pictures. I hope you enjoy it. Let me know if you do.

73 DE K7RMJ  Frank


4
New member welcome / Re: Hello All
« on: June 18, 2017, 03:09:52 PM »
Greetings Chris and welcome aboard. Glad to have you join us all.

73 DE K7RMJ  Frank

5
Ham Radio Chit Chat / Practice Ham Radio license tests
« on: May 28, 2017, 12:01:32 PM »
There are a number of Ham Radio License practice tests available on line. My favorite is at www.qrz.com (click on the RESOURCES tab across the blue bar at the top of the page, then click on PRACTICE AMATEUR RADIO EXAMS then click on which test you want to practice). The following link should take you there.

https://www.qrz.com/hamtest/

Every now and then I take the test just to see how much I have forgotten since taking it the last time LOL.

Anyway, I took the EXTRA test exam this morning and only answered 80% of the questions correctly. Give it a try and post how you did. I am amazed at how much the content has changed since I passed the extra exam back in 1998.

73 and good luck

DE K78RMJ  Frank


6
Antennas and Towers / Arkansas Antenna
« on: March 04, 2017, 06:39:35 PM »
The last post I put in this section was about the old Alliance HD-73 rotator not working and how the Mrs. got me a new one as a gift. Well, she actually didn't buy it for me, she put some cash in my ham radio savings account and said to go order what I needed.

So, here is "The Rest Of The Story" as Paul Harvey used to say. Grab a cold one and kick back in your favorite easy chair. I hope you enjoy it.

73 DE K7RMJ Frank

7
Electronic Video Blog / Re: #101 Kenwood TS-520SE Series Part 2 VFO
« on: February 25, 2017, 03:56:25 PM »
I watched this when you first posted it on YouTube and I was so impressed I just had to watch it again here this afternoon. Buddy, your skill and knowledge are amazing. There is no way I would have tried this repair. I guess I am just part chicken (but don't ask which part) LOL

73 DE K7RMJ  Frank

8
Antennas and Towers / Re: Getting ready for new tower
« on: February 15, 2017, 12:10:39 AM »
Thanks for the comment Buddy. I took your advice and took the rotor apart on the bench. I fooled the Gremlins this tome though and took the rotor apart in a large tray. None of the little ball bearings were able to escape this time LOL.

The Rotor is an old Alliance HD-73 with the old CD control box. Your advice paid off. I cleaned the bearings and races again and re-greased them. It worked! The old rotor came to life.

I started testing again to get the calibration set. No dice this time. I could get it to indicate about 270 degrees rotation on the meter, but the rotor was actually doing about 400 degrees of rotation. It would not reliably center either. I suspect there is something wrong with the positioning potentiometer in the rotor unit. It measures the correct 75 ohms and the calibration pot in the control box in series with it measures the correct resistance but it just does not indicate correctly.

Oh well, the wife got me a new Yaesu G-450 rotator for Valentines day. I must have had a LOT of "Good Husband" points saved up LOL. The rotator will handle up to 10 sq ft of wind load so it is a good replacement for the old Alliance work horse. Now I can work on the Alliance unit whenever I get around to it LOL.

Regards and thanks again for the suggestions.

73 DE K7RMJ  Frank

9
Electronic Video Blog / Re: #100 Kenwood TS-520 SE Series Part 1
« on: February 14, 2017, 11:59:47 PM »
Congratulations on video #100. That is a great milestone. I'm looking forward to the next 100.

Buddy, your skill, knowledge and tenacity are simply amazing. Thank you for posting these videos. You have taught this old dog a number of new tricks!

73 DE K7RMJ  Frank


10
Antennas and Towers / Getting ready for new tower
« on: February 11, 2017, 12:34:36 AM »
I think I mentioned that I got a new tripod tower for putting an HF beam on the roof. So, it is time to get that project moving along. The cable that goes between the rotor control box in the shack and the rotor on the tower has disappeared. I think those pesky gremlins ate it. I checked where it is supposed to be and it is not there so then I checked everywhere else and it wasn't there either.

A couple of days ago I started shopping around the internet. The cable is supposed to be 6-wire, 22 GA stranded cable. The Wireman is the only one who has it with a decent price. I'll probably only need about 75 feet of it but Wireman sells it for $0.59 per foot or in 100 ft spools. The per foot price for 75 ft was $42 and the 100 ft spool was $45 so I sent them an email and asked if they had it in stock and if not, how long will it take to get it here.

Here we are 3 days later and no response from them. Glad I didn't give them my credit card number. Oh well. Then I noticed that the Lowes hardware store had some control cable for sprinkler systems that was the right size wire but only had it in solid wire instead of stranded. Hmm, oh well, at only $25 for a 50 ft spool it was worth a try. At least I will be able to hook up the control box to the rotor and test out my rotor before I bolt it up inside the tower. So we went to Lowes Hardware this afternoon.

This evening I took the control box apart and cleaned it up. All the caps look new and none were the old paper or oil type so I figured it was worth a try so I put it back together and wired it up to the rotor. That went pretty well so I plugged it and turned it on with the rotor on the bench inside the shop here.

It lit up and like magic appeared to be working but the "Azmuth Indicator" meter went all the way over and pegged to the right side of the meter. Okay, I fiddled with the Calibrate knob and it would only go to about East. It wouldn't zero. hmmm.

Opened up the control box again and went after the Calibrate pot with some cleaner. Also, since I was into it anyhow I cleaned all the switch contacts while and guess what? It still didn't work.

I tried rotating it left, then right, then back and forth. No movement. So, I placed my hand on the rotor and tried the left and right control again and I can feel the motor trying to turn but it doesn't move.

I couldn't believe the rotor would be frozen because it worked well back in St Louis up until I took down the tower. I refurbished this rotor about 5 years ago when I put that tower up.

So my question is this. Would using 50 ft of 18 GA solid wire not work on this rotor for some reason? The manual does say to use stranded wire. I rechecked all the wire connections at the screw terminals and they are tight and no broken wires or shorts.

What do you think?

Any input is welcome.

73 DE K7RMJ  Frank

11
Ham Radio Circuits and Repair / Re: Kenwood TS-520 repair notes
« on: February 10, 2017, 06:01:00 PM »
That is great news, Buddy. The TS-520 and I are old friends. I remember when they first came out. I also really like the Yaesu FT-101 series (hint-hint) which was the competition for the TS-520 radios.

Really looking forward to your posts on this.

73 DE K7RMJ  Frank


12
Design, Project / 15 watt HF Amplifier
« on: February 07, 2017, 05:33:43 PM »
I started resurrecting an old project that I started a few years (27) ago. It's a final amplifier stage for a home brew 15 watt transmitter. I want to build an amplifier for the little CatsCan-3 transmitter. The circuit and details are in an old book from the ARRL called QRP Classics dated 1990. That should have been my first hint. It is based on an article that appeared in QST magazine dated August, 1978.

So, first I discovered that the PA transistor, MRF449A, is no longer available so I checked around the normal places for old power transistors. VIOLA! I found one at RF Parts Company in San Marcos, CA. It costs $27.00. not too bad, but they currently have none in stock and no ETA when they might have any more.

Hmmm... Just out of curiosity I checked the stats to find a modern substitute transistor. Good old Mouser Electronics had lots of substitutes but none fit exactly. The least expensive sub they had was only $29.95 plus $8 shipping and it didn't have the power rating I wanted. It was only good up to about 10 watts. The others they had started at $69.95 and up! Geeez, I almost swallowed my tonsils LOL.

The specs on the transistor are:
= Stud mount (screw type)
= 12.5 volt
= 30 MHz
= 30 Watts max output
= 12 db gain (collector/base gain hfe
= 50% efficiency
= VEBO 20V
= VCEO 40V
= Collector continuous current 3.0 Amps
= Collector peak current 5.0 Amps

The reason I want a replacement with Stud mount is that I have already built the circuit board for it and wound the RF chokes, transformers and filter inductors. They are all toroid type inductors.

Does anyone have one of these old MRF449A transistors laying around collecting dust that I could beg, buy or steal?  8-)

Or, should I just build a small 5 watt amplifier for this little QRP transmitter? It only puts out about 300 mW so a 5 watt amp would not be real difficult to build.

73 DE K7RMJ  Frank

13
CB Radio Repair Forum / Re: Dead GE Super Base.
« on: February 03, 2017, 10:03:56 PM »
Greetings nightstalker.
Here is Mike's email
mikesradiorepair@gmail.com

Regards,

Frank

14
Electronic Video Blog / Re: #98 Old Projects From The Past
« on: February 03, 2017, 08:50:57 PM »
You fly RC too! I am amazed that we have so many hobbies in common. I built my first RC plane in 1979. It was a Sig Kadet MK-I. First flight lasted a good 45 seconds befire it turned itself into a mylar bag full of parts LOL. Then I joined an RC club and learned how to fly. I flew RC from 1979 until 2014 when my vision finally gave up for the most part. Had it corrected with lens implants in both eyes but never got back into RC.

I would really love to see you build an amplifier for that 6 meter rig. I would suggest a pair of 6146 tubes for the final though instead of a single tube. If you are going to go through all the trouble of building the power supply for a 6146 you might as well do two of them.

Really good video. Thank you.

73 DE K7RMJ  Frank  aka Cuban9splat
AMA 220043

15
Amateur Radio News and Activities / MO QSO PARTY 2014
« on: February 02, 2017, 10:14:49 PM »
Okay, it has been WAY too long since anyone posted in this part of the forum. So here goes. The attachment is about how a small team of Ham Radio nuts went out in the boonies back in 2014 to enter the Missouri QSO party. Grab a cold one and kick back in your favorite easy chair. It's not as long as a book at only about 14 pages and there are some pictures included so it should be good for at least one cold brew.

I wrote the original of this article for my old club newsletter back in St Louis. The attached document is the updated version of it. Hope I didn't make too many typos.

Anyway... let me know if you like it.

73 DE K7RMJ  Frank

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