[1000mp] Re: Maybe dumb questions ?

[Mike Schatzberg]

Hello Rob:

To try and tune your Mark V into your amp a SWR of 1.5:1, you might try two 
things.

Firstly, if your input cable to your amp is just a short jumper, try a cable 
of perhaps 15 to 20 feet of RG 8 type coax instead.

Secondly, force the tuner to adjust while in the CW mode, and sending a 
string of dits at perhaps 35 words per minute.  If the tuner memories are 
full, you will want to do a memory reset first.  This is a good idea 
particularly if you change the input cable.

I have found that the tuner will reduce the indicated SWR better with the 
above method, and reach 1:1 in my Mark V.

You may see the SWR decrease with just the addition of the longer cable, and 
no tuner will be necessary at all with the 1:1 match.

If your amp has a tuned adjustable input, after you add the cable, you can 
tune the amp input for minimum SWR as well.

73 and Happy Dxing,

Mike
WB2AJI
----- Original Message ----- 
From: "Rob Atkinson" <k5uj at sbcglobal.net>
To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net>
Sent: Friday, November 04, 2005 6:43 AM
Subject: Re: [1000mp] Re: Maybe dumb questions ?


> I've driven my amp with a ts870s using its internal tuner and never had a 
> problem.   in fact, when the rig sees a 1.5:1 vswr and folds back, the 
> tuner takes that down to 1.2:1 so the rig is happy, puts out full power 
> and drives the amp more.   with my mk V the built in tuner doesn't seem to 
> want to do anything with 1.5:1 so i don't use it and because it has a 200 
> w. pa, it can provide plenty of drive anyway.   the mk V tuner seems to be 
> intended to only handle higher ratios, maybe 2:1 on up.
>
> rob / k5uj
>
> On Thursday, November 3, 2005, at 10:18 AM, Scott Manthe wrote:
>
>> Because as you tune the amplifier, the values of impedence and reactence 
>> the internal tuner in your rig sees are changing, therefore changing the 
>> output of the rig. I call this "tuner wander," because the tuner wanders 
>> around trying to find a match and I don't think it's good.
>>
>> Now, if you tune-up fast and don't change values, it's probably much 
>> better than running the rig into a huge mismatch. But for me, I prefer to 
>> turn the tuner off. Since my LK-500ZC has a very good tuned input, it's 
>> not an issue.
>>
>> 73,
>> Scott, N9AA
>>
>> John Becker wrote:
>>
>>>> It's never a good idea to use an internal tuner with an amp.
>>>>
>>> Why is this necessarily a bad idea? The input of my homebrew 4-1000 amp 
>>> apparently isn't close enough to 50 ohms on 15 meters for the Mk. V 
>>> without the tuner, but I've been driving it successfully by using the 
>>> tuner.
>>>
>>> 73,
>>>
>>> John, K9MM
>>>
>>
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