[Elecraft] Low power out on 10M

[Don Wilhelm]

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
>
>