On Mar 15, 2025, at 8:12?AM, K9HZ <bill@...> wrote:

?Sounds like the inpuu connection to the PA is high impedance (like something is not connected on the boads in front of the PA).. ?you migjt take the BpF put of the circuit temporarily. ?Just jumper across it on the LPF board pr remove ?the LPF too just temporarily. ?

Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

email:??bill@...

?

On Mar 15, 2025, at 3:10?AM, D Solt via groups.io <davesolt@...> wrote:

?Thanks Jerry and Bill. I’ll get back to this on Monday. 3 dB pad on input of PA reduces oscillation, 6 dB pad stops the oscillation?

dave

On Mar 15, 2025, at 1:34?AM, K9HZ via groups.io <bill@...> wrote:

?Remove the bpf and see what happens. ?

Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

email:??bill@...

?

On Mar 14, 2025, at 6:29?PM, D Solt via groups.io <davesolt@...> wrote:

?Yes, I agree. The amp is solid. Previously , I swept the amps and got solid performance. And, when I disconnect the drive to the amp the oscillation stops. It is being caused by something in the T41 interacting with the amp

dave

On Mar 14, 2025, at 7:05?PM, K9HZ via groups.io <bill@...> wrote:

?Something is wrong. ?The amp will NOT oscillate by itself. ??

Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

?

Owner - Operator

Big Signal Ranch – K9ZC

Staunton, Illinois

?

Owner – Operator

Villa Grand Piton - J68HZ

Soufriere, St. Lucia W.I.

Rent it: www.VillaGrandPiton.com

email:??bill@...

?

On Mar 14, 2025, at 2:13?PM, D Solt via groups.io <davesolt@...> wrote:

?Yes it is on a DL

On Mar 14, 2025, at 4:58?PM, jerry-KF6VB via groups.io <jerry@...> wrote:

?Do you have it on a dummy load?

- jerry

On 2025-03-14 13:54, D Solt via groups.io wrote:

It is the K9HZ 20W amp

On Fri, Mar 14, 2025 at 4:53?PM jerry-KF6VB via groups.io [1]
<jerry@...> wrote:

Is it a K9HZ final? Or the one with the IRF510s?

- Jerry, KF6VB

On 2025-03-14 13:52, D Solt via groups.io [1] wrote:

I got the second T41 v12 with SW ver66.4 with amplifier operating
today. Both are acting the same, oscillations around 40MHz at
several
watts when PTT is engaged. With the oscillation, I was still able
to
do the TX IQ null. I am stumped. I don't have a very accurate way
to
measure power yet; using a 50MHz TBS1052B tek scope and an HP363
kit.
dave, n3ds

Links:
------
[1] /g/AmateurRadioBuilders/message/6170
[2] /mt/111686473/243852
[3] /g/AmateurRadioBuilders/post
[4] /g/AmateurRadioBuilders/editsub/243852
[5]

/g/AmateurRadioBuilders/leave/11522011/243852/920863695/xyzzy



Links:
------
[1]
[2] /g/AmateurRadioBuilders/message/6172
[3] /mt/111686473/243852
[4] /g/AmateurRadioBuilders/post
[5] /g/AmateurRadioBuilders/editsub/243852
[6]
/g/AmateurRadioBuilders/leave/11522011/243852/920863695/xyzzy