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Drake TR7 transmit limit on digital modes

 

The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I wanted to interface with its but decide to go back to the future and something like what was available when the sig was made. I found a little VT100 terminal emulator on eBay and added a vintage keyboard and a VGA monitor. Now I can use the tnc directly by typing in commands. So for I have managed to make contacts on PSK31 and RTTY including one to Honduras.

Before I continue to work these modes I need to the digital power limits for the rig. My manual mentions that there are none if you have the for that my rig has. I am skeptical about this. What should I power to limit my power to?

Tim Gordish
W1TM
TR7 #6925
 

Do you have the optional fan on the TR7? If so there is no limit for all practical purposes. I have been running my TR7s at full output on JT/FT modes for years and they don't even break a sweat.

If you don't have the fan, get one. :)

73

-Jim
NU0C

On Tue, 23 Apr 2024 16:10:39 -0500
"Tim W1TM via groups.io" <gordisht@...> wrote:

The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I wanted to interface with its but decide to go back to the future and something like what was available when the sig was made. I found a little VT100 terminal emulator on eBay and added a vintage keyboard and a VGA monitor. Now I can use the tnc directly by typing in commands. So for I have managed to make contacts on PSK31 and RTTY including one to Honduras.

Before I continue to work these modes I need to the digital power limits for the rig. My manual mentions that there are none if you have the for that my rig has. I am skeptical about this. What should I power to limit my power to?

Tim Gordish
W1TM
TR7 #6925
 

The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with a
PS7 you should also have a FA7 on the supply for digital modes.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tim
W1TM via groups.io
Sent: Tuesday, April 23, 2024 5:11 PM
To: [email protected]
Subject: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes

The Drake TR7 has beer great rig for me. I had an old Kantronics KAM XL I
wanted to interface with its but decide to go back to the future and
something like what was available when the sig was made. I found a little
VT100 terminal emulator on eBay and added a vintage keyboard and a VGA
monitor. Now I can use the tnc directly by typing in commands. So for I have
managed to make contacts on PSK31 and RTTY including one to Honduras.

Before I continue to work these modes I need to the digital power limits for
the rig. My manual mentions that there are none if you have the for that my
rig has. I am skeptical about this. What should I power to limit my power
to?

Tim Gordish
W1TM
TR7 #6925





---
This email has been checked for viruses by AVG.
 

I would say that you want both fans even if you don't run digital modes. The fan on the PS cools the main filter caps which will extend their life. The fan on the radio keeps the internal temperature more stable across T/R cycles which reduces drift, as well as extending component life in the PA.

Any off the shelf 20CFM fan of the proper form factor, oriented to pull air OUT, will work. You don't need a gen-yoo-wine FA7.

73

-Jim
NU0C

On Tue, 23 Apr 2024 18:20:37 -0400
"Omni via groups.io" <selcor@...> wrote:

The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with a
PS7 you should also have a FA7 on the supply for digital modes.
 

I have two TR7's with their companion PS7 supplies and concur that having
fans on both the power supply and the TR7 is the best way to go. Use of the
FA7 greatly improves the frequency stability of the TR7 and prolongs the
life of the PA transistors. However, I disagree with any fan that fits is
OK. The FA7 is a Rotron Sprite SU2C1 (19 CFM) fan that was private labeled
for Drake. Power transistors are sensitive to temperature changes and
engineers design circuits to run in within a specific temperature band for
optimal performance. Too cool, while not as bad as too hot, is still not a
desired result. The heatsink in the TR7 is a patented design that relies on
the amount of air movement delivered by the FA7 to keep things within the
desired temperature band. Except on rare occasions, I let my TR7's come up
to ambient temperature before I get on the air with them.

FYI, while the FA7 tends to be a bit pricy when you can find a good one, the
Rotron SUC21 is readily available brand new for less than half the cost.
All you have to do to a stock Rotron fan is put a two prong AC plug on it.
You can easily adapt a polarized plug to fit the receptacle on the TR7 and
PS7. The only thing you might want to add to is a finger guard, which is
also not too hard to find.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jim
Shorney
Sent: Tuesday, April 23, 2024 6:32 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes


I would say that you want both fans even if you don't run digital modes. The
fan on the PS cools the main filter caps which will extend their life. The
fan on the radio keeps the internal temperature more stable across T/R
cycles which reduces drift, as well as extending component life in the PA.

Any off the shelf 20CFM fan of the proper form factor, oriented to pull air
OUT, will work. You don't need a gen-yoo-wine FA7.

73

-Jim
NU0C

On Tue, 23 Apr 2024 18:20:37 -0400
"Omni via groups.io" <selcor@...> wrote:

The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If
you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which
place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with
a
PS7 you should also have a FA7 on the supply for digital modes.





---
This email has been checked for viruses by AVG.
 

I have a box full of a 32 CFM version. These are great for a DL1000 but way too loud for anything else. The FA7 is a 20CFM fan (or 19, depending on who you ask) as you say, easy to find. IMO it does not need to be a Rotron specifically. What I am not keen on is fan controllers. They mess with the temperature stabilization idea for the rest of the radio. What definitely DOES NOT work very well at all is the bad advice out there to reverse the direction of the fan so it forces air into the radio. I have proven experimentally that this impairs cooling.

73

-Jim
NU0C

On Tue, 23 Apr 2024 20:04:05 -0400
"Omni via groups.io" <selcor@...> wrote:

I have two TR7's with their companion PS7 supplies and concur that having
fans on both the power supply and the TR7 is the best way to go. Use of the
FA7 greatly improves the frequency stability of the TR7 and prolongs the
life of the PA transistors. However, I disagree with any fan that fits is
OK. The FA7 is a Rotron Sprite SU2C1 (19 CFM) fan that was private labeled
for Drake. Power transistors are sensitive to temperature changes and
engineers design circuits to run in within a specific temperature band for
optimal performance. Too cool, while not as bad as too hot, is still not a
desired result. The heatsink in the TR7 is a patented design that relies on
the amount of air movement delivered by the FA7 to keep things within the
desired temperature band. Except on rare occasions, I let my TR7's come up
to ambient temperature before I get on the air with them.

FYI, while the FA7 tends to be a bit pricy when you can find a good one, the
Rotron SUC21 is readily available brand new for less than half the cost.
All you have to do to a stock Rotron fan is put a two prong AC plug on it.
You can easily adapt a polarized plug to fit the receptacle on the TR7 and
PS7. The only thing you might want to add to is a finger guard, which is
also not too hard to find.
 

I have original fan installed and a Astron power supply. Seems like i will be able to run full power! I love how quiet the FA7 is.

Tim Gordish

On Apr 23, 2024, at 19:04, Omni via groups.io <selcor@...> wrote:

?I have two TR7's with their companion PS7 supplies and concur that having
fans on both the power supply and the TR7 is the best way to go. Use of the
FA7 greatly improves the frequency stability of the TR7 and prolongs the
life of the PA transistors. However, I disagree with any fan that fits is
OK. The FA7 is a Rotron Sprite SU2C1 (19 CFM) fan that was private labeled
for Drake. Power transistors are sensitive to temperature changes and
engineers design circuits to run in within a specific temperature band for
optimal performance. Too cool, while not as bad as too hot, is still not a
desired result. The heatsink in the TR7 is a patented design that relies on
the amount of air movement delivered by the FA7 to keep things within the
desired temperature band. Except on rare occasions, I let my TR7's come up
to ambient temperature before I get on the air with them.

FYI, while the FA7 tends to be a bit pricy when you can find a good one, the
Rotron SUC21 is readily available brand new for less than half the cost.
All you have to do to a stock Rotron fan is put a two prong AC plug on it.
You can easily adapt a polarized plug to fit the receptacle on the TR7 and
PS7. The only thing you might want to add to is a finger guard, which is
also not too hard to find.


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Jim
Shorney
Sent: Tuesday, April 23, 2024 6:32 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes


I would say that you want both fans even if you don't run digital modes. The
fan on the PS cools the main filter caps which will extend their life. The
fan on the radio keeps the internal temperature more stable across T/R
cycles which reduces drift, as well as extending component life in the PA.

Any off the shelf 20CFM fan of the proper form factor, oriented to pull air
OUT, will work. You don't need a gen-yoo-wine FA7.

73

-Jim
NU0C

On Tue, 23 Apr 2024 18:20:37 -0400
"Omni via groups.io" <selcor@...> wrote:

The PA in the TR7 is very conservatively rated and has plenty of headroom.
The radio is rated for 100% duty cycle in SSB and CW without a fan. If
you
have a genuine FA7 you can run 100% duty cycle in SSTV and RTTY, which
place
similar demands on the PA as digital modes. if you have any concerns you
can always run the radio at reduced power such as 100 Watts. Nobody will
notice any difference on the receive end compared to the full output of a
TR7, which is typically 140-150 Watts. If you are running the radio with
a
PS7 you should also have a FA7 on the supply for digital modes.





---
This email has been checked for viruses by AVG.
Lyndon VE7TFX
 

FYI, while the FA7 tends to be a bit pricy when you can find a good one, th=
e
Rotron SUC21 is readily available brand new for less than half the cost.
Can anyone provide a link to one of these sellers? The web searches
I did led to an endless maze of very dodgy looking websites.

I also see the Rotron website doesn't recognize that part number, so
I'm not sure about "new" ones being available. I haven't dug into
their catalog yet to see if there's an obvious replacement.

--lyndon
 

I use 80mm 12 volt DC fans, which are common case cooling fans used in
PC's, on my TR7 and PS7.? The ones I use are rated at 24 cfm and 22 Db
noise level.

I have a NMB 3115FS-12T-B30, 120 Volt AC fan on my DL-1000.? It produces
a lot more noise.


73

Stan
KM4HQE

On 4/23/24 21:27, Lyndon VE7TFX wrote:
FYI, while the FA7 tends to be a bit pricy when you can find a good one, th=
e
Rotron SUC21 is readily available brand new for less than half the cost.
Can anyone provide a link to one of these sellers? The web searches
I did led to an endless maze of very dodgy looking websites.

I also see the Rotron website doesn't recognize that part number, so
I'm not sure about "new" ones being available. I haven't dug into
their catalog yet to see if there's an obvious replacement.

--lyndon
 

A.K.A. Rotron SU2C1 part number 028270.



Available on eBay new $28.00 each plus shipping.

Mouser has some equivalent NMB fans that are ball bearing for a few dollars less. The Rotron is sleeve bearing but to be fair they seem to last a long time. Generally speaking ball bearing is better suited to vertical mounting.

Or you could use PC fans run off 12V. Some of the boutique fans targeted at gamers are very quiet. Insist on ball bearings. Avoid Sunon fans at all costs.

73

-Jim
NU0C




On Tue, 23 Apr 2024 19:27:47 -0700
"Lyndon VE7TFX via groups.io" <lyndon@...> wrote:

FYI, while the FA7 tends to be a bit pricy when you can find a good one, th=
e
Rotron SUC21 is readily available brand new for less than half the cost.
Can anyone provide a link to one of these sellers? The web searches
I did led to an endless maze of very dodgy looking websites.

I also see the Rotron website doesn't recognize that part number, so
I'm not sure about "new" ones being available. I haven't dug into
their catalog yet to see if there's an obvious replacement.

--lyndon






--

73

-Jim
NU0C
 

Here you go.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Lyndon VE7TFX
Sent: Tuesday, April 23, 2024 10:28 PM
To: [email protected]
Subject: Re: [DRAKE-RADIO] Drake TR7 transmit limit on digital modes

FYI, while the FA7 tends to be a bit pricy when you can find a good one,
th=
e
Rotron SUC21 is readily available brand new for less than half the cost.
Can anyone provide a link to one of these sellers? The web searches
I did led to an endless maze of very dodgy looking websites.

I also see the Rotron website doesn't recognize that part number, so
I'm not sure about "new" ones being available. I haven't dug into
their catalog yet to see if there's an obvious replacement.

--lyndon






---
This email has been checked for viruses by AVG.

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