ht600 Tuning the Watts Up and Down

[zzpot]

Hlo ppl

Im sure someone has had one of the appart before looking for information on tuning the watts up or down.





Thanks

[kb0nly]

To the left on the picture, between the volume control and the channel select, under those flexes to the controller, is C120, an air variable capacitor. That's why there is a hole in the flex, so it can be adjust through the flex connections to the controller.

If your wanting to turn down the rf output to conserve battery life, it ain't going to help much. If you looking to make a high power radio, which that one is by the picture, into a low power radio your bettery of getting a 2w radio.

But anyway.. Now you know how to adjust it!

[zzpot]

I want to actually crank it up to max.........which way you think i should turen it clock wise or counter clock wise.


ps

Thanks for the help !

[kb0nly]

Well.. If your going to turn it up, a few words of caution!

First of all, never adjust the max power output on an HT600 without monitoring two things, the current being drawn by the radio on transmit, and the power output with an accurate wattmeter. Otherwise your just pissing away a pefectly good radio because the PA will overheat and die, to make a long story short.

When adjusting on the HT600 your watching the RF output and the current being drawn by the radio. There will be at least two different peaks that you will find. You need to tune the PA output for maximum RF but minimum current draw. Most of the ones i have checked and tweaked had one peak of full output power but excessive current, and another peak with around 1.4-1.7 amps and 4w/5w for a high power radio, a low power 2w radio averages about 750-850ma.

Clockwise increases power output, but as mentioned, if you don't do it correctly your battery life will suffer and the PA will too.

A high power H44 or H43 radio should only be set for 4W or 5W max, a H34 or H33 should be set for 2W max. Beyond that, get a different radio or an external amp.

And, the only way to measure the RF power output is to have an external RF adapter on the accessory connector. Or you can tack solder a coax cable to the output on the RF board. There is not a screw in adapter for the antenna jack to allow external antenna connection.

[kc7gr]

I want to actually crank it up to max.........which way you think i should turen it clock wise or counter clock wise.


ps

Thanks for the help !

There are some considerations you should be aware of before you decide what to do, power-level wise.

From the picture, I would guess that you've got a VHF radio there. The rated power out on those units is about 5-6 watts. Tuning them for more than that (many will do it -- I've seen a VHF HT600 make 9 watts) has some disadvantages which outweigh whatever tiny amount of positive you might get.

(1) Greatly increased heat dissipation and resultant stress on the final PA device. More simply, you're increasing the risk of early failure of your transmitter by running it at higher than rated power. The output transistor may be fairly hard to find if you end up needing to change it.

(2) Reduced battery life, especially if you do lots of transmitting or transmit continuously for extended periods.

(3) Increased risk of RF burn, or similar heating damage to body parts. There are very good safety reasons why handheld radios are limited, by FCC rules, to 5-6 watts out. You really don't want to get a whole bunch of RF energy close to your eyes, for example, as would happen if you were holding that souped-up radio next to your face.

Now, with all that said: It's really best not to exceed six watts, and you'll actually extend the life of your radio and its battery by running at five.

In order to get any noticeable improvement in signal quality at the receiving end, you would have to double your power to 12 watts out, and I can assure you that the HT600 is not capable of that.

Happy tweaking.

[440roadrunner]

In order to get any noticeable improvement in signal quality at the receiving end, you would have to double your power to 12 watts out,

Please read that again. Remember that double the power is only "1/2 an S unit"

[Will]

Remember that double the power is only "1/2 an S unit"

Or three dog biscuits!

[zzpot]

I will heed your few words of caution! ( KbOnly ) and probably print the post out and read it a few times so it can kick in.

So we are talking some new toys if and when I get in that deep to fine tune a ht600 or other handhelds ?

(monitoring two things, the current being drawn by the radio on transmit, and the power output with an accurate wattmeter)

I know you might not be able to get in great detail on how to use these on this certain model but this probably applys to all radios ! ( KbOnly )

So if you could make some suggestions on the type of equipment this would require and be used on down the line on other radios I would appreciate it.

I have the basics now !

1 Freq meter (nice)
1 Volt and Ohm meter (nice)
1 Soildering Gun (nice)
1 Phillips Head Screwdriver

1 Rib Box (with serial cable)
1 Cable from Rib box to Ht600
1 Laptop(286)

Thanks for the Input KbOnly

(Kc7qr) some disadvantages which outweigh whatever tiny amount of positive you might get. Those three points made perfect sense especially about the rf burn to your eyes. Yes and you made the correct call it is a vhf radio in fact it was the worst sounding one of my collection but I think a new speaker will probably clear that up.

Hey and the advice channel is open to you on equipment needed well to make sure they are 2 watts to start with and power drain !

Thanks for you Input Kc7qr

zz

[kb0nly]

You can monitor the current being drawn two ways, one is to just use a digital ammeter inline with an adjustable power supply, or have a little bench supply with volt and amp meters on it. I plan on building a small power supply with adjustable voltage and including panel mount digital meters for voltage and amperage. It doesn't take much of a supply, most HT's are less than 2amp draw at full power.

I usually use the first method since i have a small open frame power supply that i salvaged from other equipment that is adjustable down to about 6v. So, for the HT600 i use the voltmeter and set it to 10v, then i put my digital ammeter inline with the positive lead and connect to the radio using a gutted battery. If you have a dead or dying battery just cut the bottom off, pull out the cells and cut out the flex inside so your left with just the top contacts to the radio, solder wires to the bottom side of those contacts and now you have a power adapter. This is the same way i build battery eliminators with the addition of a regulator and diode.

Now all you have to do is slide your adapter on the radio, after removing the front of course, and you can adjust C120 through the hole in the shield and the flexes to the top of the controller. It takes a small flat blade screwdriver. If you don't already have a set do yourself a favor and go buy a precision screwdriver set, your bound to need flat and philips of miniature sizes when working on radios anyway.

If you really want to get fancy, take a beat up or damaged radio case and cut the last quarter inch off so you have the bottom end that you can screw to the radio. This way you can supply power to the radio with it removed from the case to access everything on the back and otherwise inaccessible places when it's in a case. I got this idea after seeing a Motorola servicing set for the HT600, chances are you won't find one, and if you do it's not going to be as cheap as making your own!

[kb0nly]

Ohh, and i forgot to mention.

Your going to need the external antenna adapter. Maybe someone on here will have one if your lucky, otherwise your going to have to build one. I built one from an external audio adapter, the bottom plate of the connector has all the necessary pin holes. I just reassigned the pins and then used some small RG-174 coax out the top of the adapter to a BNC connector made for that size of cable. Of course i need an adapter to go to the wattmeter or dummy load, but otherwise it works perfectly.

The Motorola version looks like an audio adapter since it uses a 3.5mm mono jack and plug to do the same thing. The have a length of small coax with a panel mount SO-239 on one end and a 3.5mm plug on the other, which then plugs into the adapter that goes on the radio. It's an ok setup, but the connector gets loose over time.

Also, find yourself a good dummy load to go on the output of your wattmeter. This is not only a good practice to avoid interference to others, but you can be assured of an accurate reading because of little or zero reflected power due to antenna SWR.

The adapter and cable is still available from Motorola, the adapter cost is $22.75, and the cable cost is $21.00, you can make one a lot cheaper!

[zzpot]

kbonly ok this sounds like its going to be fun just to see how far out of tune my collection of ht600 over the years.

Im going to get back with you mid week probably with some photo of the set up and we will go from there if you have the time.

thanks again for all your help

zz

[kc7gr]

I will heed your few words of caution! ( KbOnly ) and probably print the post out and read it a few times so it can kick in.

<BigSnip>

(Kc7qr) some disadvantages which outweigh whatever tiny amount of positive you might get. Those three points made perfect sense especially about the rf burn to your eyes. Yes and you made the correct call it is a vhf radio in fact it was the worst sounding one of my collection but I think a new speaker will probably clear that up.

Hey and the advice channel is open to you on equipment needed well to make sure they are 2 watts to start with and power drain !

Thanks for you Input Kc7qr

zz

You are entirely welcome, but I'm not the best person to ask about test gear. I tend to have relatively expensive tastes along those lines, and my recommendations would reflect that.

With that said, if you don't mind stretching a bit on test gear, you may want to consider digging around for an older service monitor. This will give you, at the bare minimum, a signal generator and transmitter analyzer in one package. Depending on which one you find, it may also have various signaling schemes (PL, DPL, paging, other?) and spectrum analyzer functionality.

If you do pursue that option, be prepared to spend anywhere from $400 to over $4K, depending on what you find and what options it has. It is my understanding that the Motorola R2200's make pretty good workhorses. You may also want to look into gear from IFR/Aeroflex, specifically the 1200, 1600, or 1900 series. All are usually available on the used arena at decent prices.

I can make some bare-bones recommendations if you don't want to hunt up a service monitor at this time. Start with a good DC bench supply, variable from 0-20V at 0-5A, and (ideally) metered for both voltage and current and shielded against RF. This will suffice for the vast majority of portable gear you may run across.

For mobile gear, you need something a bit beefier. Motorola made a monster supply, 0-40V at 0-40A, which was a strange combination of linear and SMPS in the same cabinet. I have one, and it is a monster to move, but it works extremely well and it is filtered against RF intrusion.

You will also need at least a dummy load and thruline wattmeter. You can also use a 'Termaline' (a wattmeter with a dummy load built in), though this won't let you connect an antenna if you wish.

Discussions about the type of multimeter to get have often taken on the intensity and flame-throwing of similar arguments invoking two Unix utilities, vi and emacs. Picking a multimeter is a very personal choice, but know that you cannot go wrong with Fluke.

For receiver testing, you absolutely, positively, HAVE to have a decent signal generator that can be modulated in the FM mode, phase-locked at the desired frequency, and that can be accurately adjusted for output over a range of, say, -130dBm to 0dBm. Fluke and HP both make good ones that have often appeared on the used market.

That's all I can think of for now. Happy hunting.

[wa2zdy]

I hate to sound like the downer here and the advice you've gotten is really good. But it sounds to me that before you go investing in all this nice, but expensive, test gear, you need to invest in some education.

All the test gear in the world won't help you if you don't know how to use it and what it means. And even with the right test gear, or perhaps more likely with better rather than junkier test gear, you're more likely to do more damage than good. Knowing you have good stuff can lead you into more trouble at times.

This is not a putdown, but reading your posts, it seems to me your knowledge on this subject is limited. And that's ok, we all had to start somewhere.

[zzpot]

Good morning (kc7qr)

I dont mind streching alittle

""if you don't mind stretching a bit on test gear, you may want to consider digging around for an older service monitor""

I take it this is a Motorola Service Monitor to perform a few test (tune) all built into one.

Im going to rule that moble one out........sounds like my battery charger (lol)



I know that some test equipment or tuning equipment could be for just one model of radio but more than likely it can be used on down the line for other radios in the future.

Those plugs look pretty universal !

Ok going to have to read this post a few times and digest it.

Thanks for the advice (kc7qr)

[zzpot]

Hey kb0nly

Got a few of those part and fixing to start maybe even puttin them together !


Went down to my dads today........he told me anything I took that I could not bring back......to bad i was on my hog.


Ok I think he is pulling my leg on that thing you called a dummy load because we had to go to ham shack 2 way back in the back to find this one.



I also picked up a couple of the watt/swr meters while I was down there.




backside




Now this one I think is just a swr meter



Grabbed a few of these also



Now as far as that Moto connector to connect to the radio the only one I had laying around was th ntn5557a




Ok so the picture show is over.

What I was wondering (now this might be completely wrong) was using the programing pins at the top to hook up to the swr and watt meter....I can see on a Ham set that you could just make you a female to female connector and test a Ham rig. But since the HT600 has a detachable antena I would heck finding a adapter to get down that small.

If so

Questions

1. I would like to use the ntn5557a has three pins in it im sure the placement is just for audio but I know the pins can be moved.

2. Which pins would you use or could you use to connect up to run this thru the swr/watt meter ?

3. You think Im going about it the wrong way.

I just want to check them in this post......we will do test and tune in the next post.....

Thanks again for the help !!!!!

73's

zzpot















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[kb0nly]

The dummy load is OK if your going to be below 30Mhz, usually those Cantenna's were only good on HF. I had a couple of them here myself! Just got rid of the last one this year when i bought a large old Bird dummy load off ebay, it's good through 2Ghz according to the name plate on it.

The MFJ meter is ok, but not the most accurate in the world. I used to have one of the exact same model. If you calibrate it against another known good meter it's an ok unit. I checked mine against a Bird 43 and it was ok by almost 10w!

The Heathkit unit is a SWR & Watt Meter. The left select switch is 200w, 2000w, and SWR. I think that particular meter is also HF only.

As for the adapter, yes, you can modify the audio adapter to make it an external antenna adapter. There is no screw in adapter available for the Genesis series radios, this is because unlike other radios the antenna is isolated on the Genesis series, only the center pin for example, there is no ground or chassis connection. If you look at one taken apart you will see the antenna jack just floats in the plastic top plate.

The pins, if you look on the batlabs site under HT600(E) and then click on the service cable link, Pin 10 is the coax center Rem Antenna, Pin 12 is RF Ground shield of the coax, and Pin 13 is the Sense line which needs to be tied to ground, Pin 5 is ground. When Pin 13 is pulled to ground it switches the RF from the antenna to the Rem Antenna pin on the accessory jack.

[zzpot]

Sounds pretty simple.........looks simple........ill shoot you some pictures while I make the modifcations ( no laughing on the soildering jobs ok )


Thanks again

zz

[zzpot]

Hlo kbOnly

Worked like a charm (thanks alot)

You were also right about the heathkit meter !

It was actually pretty simple had to add that extra pin for the ground from pin 13 to pin 5 ( also not for anyone else making one of these you have to keep everything tight, low as possible and remember there are two screw coming thru where the wires connect to the coax) besides that it read right off the get go.



Step one print you out a copy of the pin location for ht600 found here on this site.



Second step push out the pins and relocate them solder your leads on them and apply the heat shrink to protect those connections.



Step 3 Ohm it out, Ohm it out, Put it together and ohm it out again.



Step 4 but the big female connector on the other end.

Step 5 get your cheap radio out maybe a 34 make sure that the terms are clean the pencil eraser does work (read that on this board many times) and hook it up to the watt/swr meter and the other end to the dummy load.

Step 6 Key that bad boy in and watch the needle move.




Did a few radios and found some different readings most of the 34 read alittle over two watts but the government 43s read a full 5 on the 30 scale on all channels.


I sure appreciate all the time and help on this project.


Beware I have a few more coming up....lol

Thanks again

zz








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[zzpot]

Hlo Kc7qr

Wow those signal generators come in all shapes and sizes......wheww and I see that ppl are not giving them away......

I thought about getting around this problem for a while and what i need was something to check my transmition and recieve while programing a ht600 for the 2 meter band.

Now this is only a problem if your programing some radios that are not even in your part of the world and they have to work when they open the box......hence no repeater on that band here around home.

Another way of putting it lets say we were going to visit Los Angles.......uhhh what a thought but we wanted to program our 2 meter ht600 before we got out there. With the difference by + or - 600 and the pl transmit to activate or get into a repeater out there. Well if you tune the radios they will not talk to each other because no repeater here with those freqs. ( I had to think about this one for a while)

But I remembered your earlier post about a signal generator and I was pretty sure it was used for the recieve end of the radio.

It hit me........the cheap mans way to make a signal generator.....

Now this might sound stupid....

But I reversed programed a radio to check out the transmit and recieve on the radio I was going to be using away from home.


Radio your taking with you.

147.000 rx 147.600 tx

the reverse programed radio would be

147.600 rx 147.000 tx

Does that sound crazy or what.....and to make sure or to put a second check on it use your freq meter to make sure the transmit is right on with both units.

I just thought I would throw that in there........maybe I was laying awake thinking about the cost of a signal generator plus shipping...

thanks for the input it did help out.

zz

[kb0nly]

Step 3 Ohm it out, Ohm it out, Put it together and ohm it out again.

Always good advice. Just like measure twice cut once! A few minutes of double checking can avoid some big "Oops" or "Doh!" moments.

Good work on building the adapter!

[camcam990]

Hello, the other item you need to consider is if you turn up the r.f. power, you will most likely cause some type of damage to the receiver front end.

Most of these use a solid state type of switch, diodes. It may cause the receiver to stop hearing normal signals. I would check the prints and see how the transmit/receiver ant switching is performed before adjusting any power. This might save you some time and grief. The other item to consider is that of overdriving the final and causing a lot of extra unwanted and not if FCC compliance RF spurs. This can be checked with a spectrum analyzer. There are a number of reasons why the rf power is not turned up to the max on these radios.

Thank You all for the time