¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. DRAKE-RADIO
  2. Topics

TR7 drift

 

Hi,

New to the forum here.

I've had a C line for some time but recently have got a TR7.

From switch on, there is a gradual slow drift downwards in frequency of both transmit and receive.

During short QSO's this isn't noticeable, but longer QSO's I end up getting comments from the station I'm working.

Over the first hour or so the frequency goes down by approx. 1.6khz, after this it seems to stabilise.

Is this normal for the the TR7, or is it a sign of something not right?

It surprised me that the drift seems greater than my T4XC/R4C line-up

Any thoughts appreciated

73, Dave G0GKH
 

¿ªÔÆÌåÓý

I also recently acquired a loaded TR-7. It came with a German version of a VFO stabilizer, and it keeps the TR-7 within 10Hz from dead cold start. Elcon is making the Elcon 34 frequency stabilizer. I used one on an RV-4C and am very happy with the results.

Dale W4OP
 

It bears noting that the original specification for frequency stability for the TR7 is less than 1 kHz during the first hour and less than 150 Hz / hr thereafter.

I know that we have all become spoilt from using modern equipment that has much tighter tolerances but unless you're using these sets for modes that demand high precision, the original spec is reasonable.? Of course, everyone has their own desire for how they use the equipment.? My point is that if it drifts less than 1 kHz in the first hour, it is operating within spec and you likely have no bad components.

73,

Steve Wedge, W1ES/4

Time flies like an arrow.? Fruit flies like a banana.

Sent with secure email.

On Wednesday, February 7th, 2024 at 9:57 AM, Dale Parfitt <PARINC1@...> wrote:

I also recently acquired a loaded TR-7. It came with a German version of a VFO stabilizer, and it keeps the TR-7 within 10Hz from dead cold start. Elcon is making the Elcon 34 frequency stabilizer. I used one on an RV-4C and am very happy with the results.

Dale W4OP
 

They all have some small amount of drift. How much depends partly on how well the PTO has aged and the accuracy of the factory temperature compensation. I found that mine have been plenty stable enough to run digital modes like JT65, JT9, FT8, etc. I have wondered if it might help to replace the Zener in the PTO with a high stability precision regulator. That may be a project for "someday". Of course the 7-line radios will have a different warm-up curve than the radios that glow in the dark, but every radio has a warm-up time spec. I tend to just let my 7-line run 24/7.

One point of trivia that is not thought about much is temperature variation over T/R cycles. Do you have the optional fan on the back? I did some measurements some years ago and found that a properly installed fan pulling air out of the radio does actually help keep the temperature inside the radio near the frequency determining parts more stable across T/R cycles, especially if you are running hard. The heat from the PA deck has to go somewhere, and with no fan some of that heat makes its way into the rest of the radio.

73

-Jim
NU0C


On Wed, 07 Feb 2024 05:09:07 -0800
"Dave G0GKH via groups.io" <g0gkh@...> wrote:

Hi,

New to the forum here.

I've had a C line for some time but recently have got a TR7.

From switch on, there is a gradual slow drift downwards in frequency of both transmit and receive.

During short QSO's this isn't noticeable, but longer QSO's I end up getting comments from the station I'm working.

Over the first hour or so the frequency goes down by approx. 1.6khz, after this it seems to stabilise.

Is this normal for the the TR7, or is it a sign of something not right?

It surprised me that the drift seems greater than my T4XC/R4C line-up

Any thoughts appreciated

73, Dave G0GKH






--

73

-Jim
NU0C
 

Jim

Thank you for your comments.? Very helpful.? And than you to Dave for raising the topic.? I know now the cheap options with mine.

Nigel


On Wed, Feb 7, 2024 at 7:04?PM Jim Shorney <jimNU0C@...> wrote:

They all have some small amount of drift. How much depends partly on how well the PTO has aged and the accuracy of the factory temperature compensation. I found that mine have been plenty stable enough to run digital modes like JT65, JT9, FT8, etc. I have wondered if it might help to replace the Zener in the PTO with a high stability precision regulator. That may be a project for "someday". Of course the 7-line radios will have a different warm-up curve than the radios that glow in the dark, but every radio has a warm-up time spec. I tend to just let my 7-line run 24/7.

One point of trivia that is not thought about much is temperature variation over T/R cycles. Do you have the optional fan on the back? I did some measurements some years ago and found that a properly installed fan pulling air out of the radio does actually help keep the temperature inside the radio near the frequency determining parts more stable across T/R cycles, especially if you are running hard. The heat from the PA deck has to go somewhere, and with no fan some of that heat makes its way into the rest of the radio.

73

-Jim
NU0C


On Wed, 07 Feb 2024 05:09:07 -0800
"Dave G0GKH via " <g0gkh=[email protected]> wrote:

> Hi,
>
> New to the forum here.
>
> I've had a C line for some time but recently have got a TR7.
>
> From switch on, there is a gradual slow drift downwards in frequency of both transmit and receive.
>
> During short QSO's this isn't noticeable, but longer QSO's I end up getting comments from the station I'm working.
>
> Over the first hour or so the frequency goes down by approx. 1.6khz, after this it seems to stabilise.
>
> Is this normal for the the TR7, or is it a sign of something not right?
>
> It surprised me that the drift seems greater than my T4XC/R4C line-up
>
> Any thoughts appreciated
>
> 73, Dave G0GKH
>
>
>
>
>



--

73

-Jim
NU0C
 

Thanks for the all info Jim,

Yes, my TR7 has the fan fitted.

73, Dave

1 - 6 of 6