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Author Topic: Equipment AAR: R-105M radios and "Vehicle Mount" antenna  (Read 3406 times)
abica
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« on: March 29, 2010, 01:55:52 pm »

Item:

R-105M, antenna feed line, vehicle mount bracket, sectional mast antenna

The Plan:

The R-105M was to be our main stationary radio platform for EW3.  5 were taken into the field, packed into typewriter cases (2 radios plus equipment in each of 2 cases, 1 radio plus spare goodies in the 3rd case)

2 R-105 sets were to be used in the TOC- one for admin and one for the Company net.  3 were sitting on standby for forward deployment as needed.

The 2 TOC radios were to utilize feed lines hooked to vehicle mount brackets (which were attached to big green metal stakes driven into the ground), and mast sections were to be assembled for emitters.

All radios were checked and calibrated prior to deployment.  Feed lines were matched up with vehicle mount brackets to ensure good fit.  (This stuff is Soviet, remember)  Cheesy

The performance:

I was very pleased with the R-105M's performance at EW3.  

Day 1- we set up the Admin net.  I pulled Mike in from his duties and sat him down at the table with a piece of paper to calculate electrical length for our antennas.  

Swayze had trouble receiving my transmissions and suggested deploying a longwire (beam) antenna.  I quickly pulled out our diagnostic gear and found that I had made an error in calibration back at Depot.  Quickly re-developing my calibration procedure and utilizing diagnostic equipment, I got back on the Admin net and we were instantly pleased/relived by the results.  (Calibration detail at the end of this document).

"Telephone" style handsets were used in the TOC, with no apparent problems.  Stylish, effective, and comfortable to use, but the "Headset" type is still the best equipment...by a slim margin.

Setting up our Co. comms was generally simple after the improved calibration system was put in place.  

Our antenna scheme worked VERY well.  No mess in the TOC, just a couple lines going out to the antenna farm.  Turning the antenna from a 1/4 wave emitter (7 mast sections) to a 1/2 wave emitter (13 mast sections) did not seem to give us any benefit at the ranges we worked with.  The 1/2 wave antenna did deflect in the wind a great deal...just like the manual said it would.

Battery life- given the fact that we used our radios "as needed" and monitored the Admin net on a scanner, I have nothing to report.

Issues:

We are still having battery pack issues!  I soldered up battery packs made from 2x Alkaline D cells.  In retrospect, I think the alkaline batteries are really pushing the power envelope for the R-105M...a little too much voltage.  Must revisit this.  

Vehicle interference- the BTR-40 (I think) was running outside the TOC at one point...YIKES.  

While connection to the KFG-78 worked, I noticed some weird anomalies if both R-105s were turned on.  I don't remember exactly, but I noticed strange things while touching various metal radio parts.  Making sure the two radio sets were not physically touching in any way mitigated whatever weird problem I had, so I didn't make detailed notes.

To copy Swayze: "Radios were underutilized.  Sort of a bummer given that we spent more effort than is reasonable to even imagine getting all of this stuff set up."   I agree.  But in our case, I felt like we Soviets were really living up to the "Soviets don't trust radios" bit we've talked about.  

Sadly, I don't think the "average troop" gets too much out of our period radio systems just yet, but as time goes on, they will, once we can assign guys to commo watch, and once we have manpower to necessitate greater radio comms in the field.  Especially if they don't have to hump the R-105 too much...  Cheesy

Now that we're really getting good with the 105, I think we can start getting more folks involved in their operation.  

The R-105M was not deployed forward this year, but as our confidence and competence grows, this becomes a very cool and distinct possibility in the future.


The fixes:

Sustain use of the R-105M as Admin radio and TOC base station.  

Figure out reliable power packs and evaluate use of alkaline batteries (voltage)

Examine feed line ring connectors and vehicle mount "screw" sizes to see if we can match stuff up better.

Double check emitter length, try to figure out some kind of fancy "velocity" math stuff regarding feed lines, then finalize the number of mast sections required for the 105's operating freqs.

Develop "inside instruction plate" insert based on everything learned.  Photoshop that bugger up to look like the original, then stick laminated instructions in the set atop the originals.  

Label 105 faceplates that are going out into the field.  Maintain label-free faceplates for the TOC (for appearance's sake) and provide a laminated "cheat sheet" for novice operators.


~~~

Calibration Procedure Addendum

~~~

1) Install batteries
2) Attach PRM-34 to radio
3) Tune to the High Calibration Point on the radio dial
4) Calibrate "antenna" to maximum deflection on the meter
5) Measure FWD PWR
6) Open the TOP of the two calibration screw...cover...screw...things.
7) Measure FREQ (whatever it's called on the PRM-34)
Cool Adjust FREQ reading on the PRIM to precise frequency by turning the TOP trimmer screw you uncovered.
9) Replace "cover" screw on TOP hole.
10) Open BOTTOM "cover screw"
11) Activate the crystal calibrator and calibrate the radio's reception circuit by obtaining a zero beat while turning the BOTTOM trimmer screw.
12) Replace screw cover, disconnect PRM-34, hook up and match to antenna, and be happy.
« Last Edit: March 29, 2010, 03:54:48 pm by abica » Logged

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aswayze
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« Reply #1 on: March 29, 2010, 03:05:33 pm »

Did you guys use the PRM-34 to determine your emitter length at all? 

That would seem like the wise way to do it.   Set up your proposed emitter, adjust your antenna trim to max fwd power reading on the PRM then start playing with adding/removing sections to see if you gain or lose reflected power.  Once you find the emitter with the LEAST reflected power, adjust the trimmer to the lowest reflected reading. 

Math is good but it is hard to say where you electrical length “starts” on that system since your feed lines are a little iffy looking. 

Did you employ counterpoise wires on your masts or just an earth ground? 


Also, keep in mind you can try traditional carbon zinc “heavy duty” D-cell batteries, they are cheap and voltage seems to drop off a lot faster on them compared to Alkalines, that might be a good match for the 105M, probably a better match for the KFG as well. 

As far as the BTR and noise, has the ignition system been converted over to a non-shielded system on that one? 

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abica
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« Reply #2 on: March 30, 2010, 09:03:06 am »

No, we did not use the PRM for emitter length.  I actually considered it, remembering "hey, I remember reflected power something-or-other fancy-pants thing while using the PRM on the BTR" but Mike assured me (more importantly proved to me through computed examples) that there was no reason to, essentially since the mast sections are so long.

But the way you're putting it sounds really compelling, and might be able to combine some of these individual "tuning" operations into a more effective system.  I'm willing to bet that we're replicating the mysterious diagnostic equipment the R-105 depot repairman plugged into the front of the set.

So in short, (understanding more here) WE calculated emitter length from the connection of the feed line to the antenna bracket up to the tip of the mast.  But the emitter might start earlier in the system, back up the feed line.  Also, I'm curious as to how "velocity" I've read about in feed lines would change the numbers.  Hence, the PRM system.

We did not employ counterpoise- just earth ground through the stake.  (The feed line has a wire that hooks to the would-be counterpoise connector on both the radio and antenna mount sides)

More on power- the alkalines started off pretty hot, and stayed at the very upper limit of rated voltage for a long time.  Without being precise at all in the statement, voltage began to taper off halfway through battery life, and did so consistently.  This was surprising, because I remember using alkalines before and staying well within the set's rated voltage.

These Heavy Duty cells sound like they're worth exploring.  Hell, I wonder if that's what we used as an expedient last spring when we were doing testing?

I mentioned the BTR- I'm almost positive it was the BTR chomping on radio waves, but it's possible that it was a different vehicle.  But, in my foggy memory, I asked someone "what the heck is running out there" and was told "BTR."
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tascabe
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« Reply #3 on: March 30, 2010, 09:40:40 am »

That makes more sense then when I was told the UAZ was causing it.

The UAZ is fully shielded as for a command/radio version - though the distibutor shield cap is off right now.

As far as I know the BTR is not shielded in anyway.

Remember I also had the Deuce out there running for a bit to power the MBUs - but that was one night.
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« Reply #4 on: March 30, 2010, 09:48:42 am »

I can guarantee you that the BTR messes with radios.  We had a big problem with it during the Comms training weekend, while driving it around. 
So I completely believe that it was a problem at EW.

Equally sure that the Deuce(s) don't cause trouble.  The alternator on the trucks is shielded, and we all know that electricity and M35s don't mix!  Grin
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abica
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« Reply #5 on: March 30, 2010, 10:33:58 am »

It was definitely the BTR then- both it and the UAZ were parked outside the TOC. 

Good to know.
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« Reply #6 on: March 30, 2010, 10:49:23 am »

None of the up to 3 electrical items on the deuce seem to cause any electrical interference with radios.

Most of the time, when you get that stuff it is spark causing electrical stuff like ignition systems that make the racket, hence why I tend to cast a suspicious glare at the BTR since it is gas powered and I knew the UAZ was shielded. 

Getting shielded stuff for the BTR would probably not be that tough although it might be semi-costly. 




 
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« Reply #7 on: March 30, 2010, 03:10:53 pm »

UAZ isn't that shielded, I was picking up interference from it on 392 traffic as well...
I.e. I had a 392 fired up and when the UAZ was coming/going from the TOC area I could hear it causing an undulation in the headset as I was listening/transmitting.

Just wierd comms stuff I guess.

Was also last year able to pick up interference with the generator and our comms but this year it didn't seem a factor...go figure.
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abica
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« Reply #8 on: March 30, 2010, 03:35:13 pm »

I don't think we were using the super-cool generator last year though.

That interference on the 105 from the BTR was friggin' POWERFUL too, by the way- almost totally jammed signals at a distance of road to TOC.
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