Anytone Smart and a KL203

[Bow]

So I was playing around with my Anytone Smart CB and an RM Italy KL-203 this evening for a little bit.

I was researching the worderful world of the internet, and it seems the general thought is the KL-203 is a 100w PEP amp at best, while still being "clean".

Knowing my Anytone Smart is a pretty foolproof radio; mine is stock, only adjusted for 100% modulation by me with a O'Scope and a 1.50w carrier for driving a KL-60 I had behind it last time I played with it. I have also drilled out the microphone hole in the plastic...

I decided of would be a good test rig to play with the KL-203.

Test equipment:
-Signal generator set a1khz Sine Wave @ 0.03v fed into the rear of the mic circuit board
-Rigol 100mHz O'scope
-Diamond sx-600 Watt meter
-Dummy load
-Megawatt 30a power Supply set at 13.7v

The best I could get it to run clean
Anytone: 1.75w carrier
KL-203: 22w carrier
50w PEP

Anything more the that, the positive peaks started to flat top.

I realize the Diamond Watt meter isn't a true, accurate PEP measuring Watt meter, but I thought it was interesting I couldn't get anymore out of it....

Doesn't that seem a bit low, or is it my curse of wanting to run clean and setting radios up with an O'scope and not being a meter Swing junky...

Either way, the Anytone sounds really good on FM, I was using a Stryker SR-655 with a full range external stereo speaker...

I was just curious what you all think of my findings....

 

[Shadetree Mechanic]

I used to set my modulation and mic gain by listening to a monitor radio with no antenna and headphones. Then I got a scope, and I was able to see what I was doing. What I found is that there is a little leeway as the modulation is turned up, it will start to look bad on the scope but will still sound good. I would be interested to see if you would get the same results. I always set it up using my voice talking normally. The monitor radio will help you find the correct distance to hold the mic too. I always do a quick check on the monitor when I power up, along with an SWR and power check.
Chris

 

[Bow]

Thanks Shadetree,

I can understand that, but I like to see what its doing, and if I see Flat lines or Flat Tops, I'll back it down.

BTW, that Anytone will pass Audio Freqs down to 100Hz. It loses a good bit of Modulation on AM that low, but FM passes it like a champ...

 

[Shadetree Mechanic]

Thanks Shadetree,

I can understand that, but I like to see what its doing, and if I see Flat lines or Flat Tops, I'll back it down.

BTW, that Anytone will pass Audio Freqs down to 100Hz. It loses a good bit of Modulation on AM that low, but FM passes it like a champ...

I agree, I don't like box cars either. I haven't tried FM mode on my smart, I am going to check that out.

 

[Bow]

Let me know what you think of the FM...

By the way, the audio gets better on these radios when you bore that little mic hole out to about 1/4"

 

[Robb]

Bow:
Nothing wrong with a SX-100 meter at all.
Like most meters, within 10% IIRC.
What size dummy load/watts?
Do you have a RF sampler?
No? Build one - it's simple and needed.

 

[Bow]

I actually use an old MFJ-267 "1500 Watt" dummy load, the one with the Cross needle meter.

I drilled and mounted a BNC on the back and ran a "rf smapler" pickup wire down the length of the resister. then run that straight to the O'Scope

 

[Bow]

So this is basically what I did:

Removed the Antenna/Dummy Load Switch
Hard wired the input lead to the load. Thayt gives me a 1.0-1.1 SWR.

I used the old Output SO-239 and soldered a 12g wire to the center pin, then paralleled the wire to the load resistor, under the heat shield, the entire length of the resistor.
Then use a PL-239 to BNC adapter on the old Output to the O'scope



However, looking at the rear circuit boated, there is a torriod already there for the SWR function of the meter in the front. I might be able to tap that coil connection points on the board to feed the scope.

It would be nice to come IP with something a little more "calibrated" to feed the O'scope to use it more for accurate measurements instead if just a visual reference

Unfortunately, the meters on the front are pretty worthless, I can get them to zero out anymore, nor can I find a reference to calibrate this MFJ-267 circuit....

 

[Bow]

So using my current "Parallel Pickup Wire" setup, I get O'scope readings like this with the Anytone and KL-203

Carrier:

Modulated:



Great for a visual reference, but not good for making true measurements.... because with the proper O'Scope feed and a littkle math, you can figure out the true output Watts...

 

[Bow]

On a side note...

Using the adjustment screws on the front of the meter, I was able to "0" both needles on the meter

Using the variable cap on the circuit board in the back, I was able to match the SWR that my Diamond SX-600 was showing.

And by tweaking R120 on the front board, I was able to match the power reading shown on the SX-600.

So when modulating as shown in the previous post, both meters displayed:
20 W Carrier
50 W Modulated
With the SX-600 in PEP mode, it still showed 50w, but the MFJ-267 settled out around 100w PEP...

Is it accurate?

Definite Maybe...

But I gots some SWING!

Yeah buddy!

Now to figure out what the other 3 pots on the front board do...

Oh, and I added a small cooling fan, because I had one

 

[Bow]

On an interesting note.... I have found some calibration procedures for the MFJ-267 on a Japanese Ham Site : https://www.qsl.net/jg7amd/equip/eqacc.html

MFJ-267 - Dummy Load

1. Remove cover from mfj-267.（カバーは外さなくてOKです、）
2. Set switch on back of mfj-267 to antenna position.
3. Set high/low power switch to Low (out).
4. Set output to 100 Watts on bird meter.
5. Adjust R120(F-LOW) so that mfj-267 reads 100 Watts.
6. Set high/low power switch to High (in).
7. Set output to 500 Watts on bird meter.
8. Adjust R110(F-HIGH) so that meter on the mfj-267 reads 50 Watts. When in the high power position, all readings on the meter scales are multiplied by 10 so this is actually 500 Watts.
9. Unkey transmitter.
10. Reverse the coax connections on the 267, by connecting the line from the wattmeter to the antenna connection, and the line from the dummy load to the input connection.
11. Set the high/low power switch to High (in).
12. Set output power to 200 Watts on the bird meter.
13. Adjust R103(R-HIGH) so that the reflected meter on the 267 reads 20 Watts. When in the high power position, all readings on the meter scales are multiplied by 10, so this is actually 200 Watts.
14. Unkey transmitter.
15. Set high/low power switch to Low (out).
16. Set output power to 20 Watts.
17. Adjust R119(R-LOW) so that the reflected meter on the 267 reads 20 Watts.
18. Unkey transmitter.
19. Return all gear to normal operating conditions.

Then I found this pdf at mods.dk

So I might try to calibrate it tonight...

I really am fighting the urge to drop the coin for an LP-100A...

 

[Dmans]

Bow,
Re: RF Sampler.

I built one of these (see attachment). I think I have about $5.00 in the whole thing with quite a few items scrounged from my junk box. I did buy a 1 foot piece of RG-402 (cost-$7.00) and used about 1.5 inches of it.

It looks kind of crude but works very well on the Spectrum analyzer and scope. It does provide a measured 50db coupling factor. Pictures to follow.

73
David

 

[Dmans]

Pictures of the crude looking 50db sampler.

The last picture is of the leftover RG-402. This is serious HARD line. The outer jacket is the braid and is a copper tube.

73
David

 

[Dmans]

I meant to include this pic. The generator was sweeping 20-30Mhz. The solid line is from the sampler output.


73
David

 

[Bow]

Thanks,

but what does the circuit look like?