Low power out on 10M

[James T. "Jim" Rogers, W4ATK-2]

        Yeah, I know this subject has been kicked around for a while, but none the
less..... When I built the K2, I had no trouble getting the 10W out on 10M.

        1) I have rewound T2 and elevated it above the board 1/16 inch.

        2) Band Power at W6 Measured output.
             20 -33 DBM 2.0 WATTS
             10 -29.3 DBM 2.0 WATTS

        From the above measurements it seems that at this level the drive at W6 and
the power out of the Low Pass filter at the antenna connection are tracking
fairly well.

        3) Band Power at W6 Measured output.
             20     -26.3 DBM 10W
             10     -26.7 DBM 5W

        The drive is still up there, but whoa nellie! What happened to the output?
This is where 10M flattens out. You can ask for more power, but it just
isn't there. Back in the old days, I would start replacing empty state
devices<G>.

        I have checked the components around the 10/12M Low Pass Filter and all
seem correct.

        Anybody seen this and got a suggestion.....?

Jim, W4ATK

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[Darwin, Keith]

 
I'm clueless but can offer an observation for you to laugh at and
ignore.

On 10 meters, -29.3 DBM yields 2.0 watts while -26.7 yields 5 watts.
The change in drive level is about 3 dB which is twice the power so that
looks like what I'd expect.

On 20, the change is about 6 dB or 4x power and you show 2 watts going
to 10.  Again, it is in line with expectations.

- Keith KD1E -

-----Original Message-----
From: "Jim" Rogers, W4ATK
        2) Band Power at W6 Measured output.
             20 -33 DBM 2.0 WATTS
             10 -29.3 DBM 2.0 WATTS

        3) Band Power at W6 Measured output.
             20     -26.3 DBM 10W
             10     -26.7 DBM 5W

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[Don Wilhelm-3]

Jim,

There are 3 stages of RF amplification in the transmit chain between the W6
jumper and the LPF, you will have to refine the search a bit - right now,
all I can say with certainty is that the problem lies between W6 and the
LPF.

I would suggest checking all the components in the base circuit of Q7 and Q8
as well as those components associated with Q5 and Q6 - particularly the
capacitor values.

Make RF Voltage measurements at the base and collector of Q6 and the bases
of Q7/8 (and collector of Q7/8 if you are using a 'scope with a 10x probe)
with the requested power set for 10 watts and see where it falls off
(compare 10 meters to 20 meters as you had been doing).

Once you determine the point where the gain drops drastically on 10 meters,
you can zero in on the problem quickly.

73,
Don W3FPR


> -----Original Message-----

>
> Yeah, I know this subject has been kicked around for a
> while, but none the
> less..... When I built the K2, I had no trouble getting the 10W
> out on 10M.
>
> 1) I have rewound T2 and elevated it above the board 1/16 inch.
>
> 2) Band Power at W6 Measured output.
>     20 -33 DBM 2.0 WATTS
>     10 -29.3 DBM 2.0 WATTS
>
> From the above measurements it seems that at this level the
> drive at W6 and
> the power out of the Low Pass filter at the antenna connection
> are tracking
> fairly well.
>
> 3) Band Power at W6 Measured output.
>     20     -26.3 DBM 10W
>     10     -26.7 DBM 5W
>
> The drive is still up there, but whoa nellie! What happened
> to the output?
> This is where 10M flattens out. You can ask for more power, but it just
> isn't there. Back in the old days, I would start replacing empty state
> devices<G>.
>
> I have checked the components around the 10/12M Low Pass
> Filter and all
> seem correct.
>
> Anybody seen this and got a suggestion.....?
>
> Jim, W4ATK
>
>

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