No. The PS75 has the same mains routing as the PS7. The PS7 is more appropriate for the TR7 because of the higher current output rating. While the PS75 can be used with the TR7 it was more targeted at the TR5 which has a somewhat lower power requirement.
73
-Jim
NU0C
On Tue, 28 Nov 2023 14:35:00 -0500
"Joseph K4JNG" <jgraif1@...> wrote:
So¡buying a PS7 to replace my PS75 was a mistake?
joseph n. graif
k4jng
-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Jim Shorney
Sent: Tuesday, November 28, 2023 2:32 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] TR7 low band TX oscillation
This is a thing. Unfortunately not one of Drake's best ideas. I have seen at least one case where the owner added a toggle switch to the front of the PS7 and eliminated the mains feed through the TR7. To make this complete you need to use a DC fan in place of the FA7.
A less drastic solution that I have considered is adding a low voltage circuit to the PS7 to sense the TR7 power switch and turn on mains power to that big transformer with a relay.
73
-Jim
NU0C
On Tue, 28 Nov 2023 13:55:05 +0100
"Dieter Horst" < <mailto:dieter.horst@...> dieter.horst@...> wrote:
Hi Patrick,
The culprit is the PS7 connector which brings mains voltage in your
radio including hum you won¡¯t get rid of. So it is not the PSU itself that brings the hum in your radio.
I use a little relay box to switch on my PS7. So leave your
electrolytics, just get the mains out of your radio and you¡®re done.
73 de Dieter DL5RDO
Von meinem iPhone gesendet
Am 28.11.2023 um 07:00 schrieb Patrick TK5EP < <mailto:pegloff@...> pegloff@...>:
?
Hi Jim,
After a lot of tests, PSU swaps, etc... I came to the conclusion that this TR7 is VERY VERY sensitive to any noise, AC spurs, hum that are present on the 13,5V supply voltage.
Even is powered with a external PSU but leaving the PS7 control connector connected, there is a hum on the signals.
All signals (RF, audio) are affected with these noises, sometimes it is very noticeable on the receiver audio.
The scope on the loudspeaker shows that on the 50 Hz main is wobbling the AF signals.
Even with a "clean" PS7 output, it is noticeable.
The first thing I'm thinking about is the VCO board. I will order all caps and change them.
Has anyone already treated this problem ?
Thanks and 73,
Patrick
Jim Shorney