Operation East Wind Forum

Archives => East Wind III AAR => Topic started by: abica on March 30, 2010, 08:46:10 am

Title: Equipment AAR: KFG-78 "Speaker Thing"
Post by: abica on March 30, 2010, 08:46:10 am
Ahh, the venerable Kommandeursfernbediengerät...a.k.a. "Commander's remote device"


Use the KFG-78 as an external speaker to monitor 2 R-105M radios.  Power with external 12V marine battery.


The KFG-78 boasts one heck of a speaker.  I believe it was originally designed for AA missile battery commanders, so it had to be loud- and loud it is.  

Having an external speaker alongside the radios was a help- it allowed everyone in the TOC to hear incoming traffic.  This served multiple purposes.  Everyone was informed of what's going on with the transmitting unit, and anyone listening in had an opportunity to help decipher poor quality transmissions..."did he say frog or log?"  (We wouldn't really put two similar words in an SOI, but you get the drift)


Power from the Big Battery would have probably lasted the entire event without once turning off the KFG.  We did not test this theory, as we conserved radio batteries and conducted hourly or half-hourly comms.  

While the Big Battery provides a more-than-ample supply of power, which is a good thing, I think we should consider regressing to internal D-cells and establish their burn time- one set might or might not be sufficient for an entire week.  This would free up a Big Battery for another task.  (We could certainly run on D-cells if we're doing comms check-ins as opposed to a continually open net, which is more practical depending on how you're operating)

There was also some sort of issue with the two R-105 radios connected to the KFG-78.  Touching various metal bits on the radios caused some sort of problem, and removing the KFG connection made this problem go away.  Not a huge deal, but something that is worth further investigation.

Fixes, or rather, stuff to look into:

~Internal D-cell burn time

~Investigate the KFG-78's "advanced features" such as retransmission capability.  My German is poor, but it was good enough to figure out which lead on the external power cable should be + and -, so with time, maybe I could figure it out.  (Although retrans is a low priority, it would be cool to figure it out)

Title: Re: Equipment AAR: KFG-78 "Speaker Thing"
Post by: aswayze on March 30, 2010, 10:45:44 am
D-Cells add up cost wise, perhaps try 12V off of one of the Werker batteries?   Those are at least cheap and easily recharged. 

Title: Re: Equipment AAR: KFG-78 "Speaker Thing"
Post by: abica on March 30, 2010, 12:13:07 pm
I need to test the burn time on the KFG to determine the best approach.  I have a suspicion that a set of D-cells lasts a long long time in this device.

It takes roughly 12 D cells.  Just thinking about the burn time I get on a little portable radio in the garage, I wonder how many days of continuous operation one set of batteries will provide?  If we could make it through the event on 1 set, 10 bucks is probably worthwhile on the cost/convenience scale.  1 battery change during the event, it already starts to suggest using something rechargeable.

I'll grab the KFG from Brett at some point, likely may-june (recalling having the radios at my house for testing that time last year) and I'll burn a fresh set of D cells in it to get a good estimate.  Hmm...need a signal to feed into it or else the speaker doesn't speak, but that shouldn't be hard to figure out.  

Nothing wrong with running it off an external battery, mind you, but it might not be necessary.  

I wonder if power consumption is listed in the manual?  Those numbers, combined with data from a D-cell burn, might allow sensible decisions moving forward.

Just brainstorming here (not always the thing to do in public) but I guess a consideration is how the KFG is used.  It was totally unnecessary to use external power for EW3, other than proof-of-concept.  But in an environment lending itself to a busy radio net, monitored 24/7, external power might be the way to go.  Assuming one load of batteries would last through a week, even $10 per week adds up after a while, and if you've got ample external power, might as well use it.  Sensible thing to do.

Title: Re: Equipment AAR: KFG-78 "Speaker Thing"
Post by: tascabe on March 30, 2010, 12:17:56 pm
An large battery is not that big a problem - actually much easier and cheaper in the long run than D cells.

Will not need the huge one we had this year - a much smaller one would do the job just fine.

Given that in the future we will have a large battery to run the R105M radios off as well -( using a circuit that Houli will be making for us )- the large battery issue becomes an even smaller issue and the D Cells become a much bigger hassle and expense.

Title: Re: Equipment AAR: KFG-78 "Speaker Thing"
Post by: abica on March 30, 2010, 12:23:20 pm
An all-in-one power solution would be friggin' awesome! 

There are cooler expendables to spend money on than batteries, that's for sure.