I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK
I've been using the SSB Electronic preamps for years now. Thye handle the ~50 Watts from my FT-847 just fine. 73, Jim
On 02/16/2011 09:59 PM, Ted wrote:
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
At 12:59 PM 2/16/2011, Ted wrote:
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Ted,
Not without relays to bypass the preamp when transmitting. Several outfits make preamps with RF detect and internal relays but be careful not to exceed their RF power ratings. ARR make a fine preamp and I have used them for years. The mgf-1302 is the standard device in them but have become scarce (hard to find). Not sure what ARR is using as a substitute, but you could stock up on a handful and do your own repairs.
I have been the beneficiary of a couple dozen H-J Fets (NE334S01) that drop into the ARR and have half the NF (typ. 0.24 dBNF). They are smaller devices so a bit harder to handle. I just installed one in an old P144VDG ARR preamp and had only to substitute the 100-ohm resistor with a 270-ohm to supply Vds=2.4v (mgf-1302 take Vds=4v).
I will be installing it on my 2m-eme array in a couple days and will see how it plays.
73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw*, 432-100w, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep [email protected] ====================================== *temp not in service
I use preamps from SSB and have been very happy with them. Another popular brand is Landwehr, as is ARR (with which you're having trouble).
My radio is an Icom IC-821 which provides power via the coax when in receive-mode. The radio automatically removes the preamp power before keying the transmitter which protects the preamp. Other Icom and Yaesu radios have this feature; the Kenwood TS-2000 may also support this.
Note that ARR also sells preamps with RF sensing with either a 25 watt or 160 watt rating.
Good luck.
73, Steve N9IP
Hello Ted,
You didn't mention whether you had an ARR pre amp with the RF sensing.
I have been using my ARR pre amp for 15+ years outside (with a cover). I open it every year or two and the inside still gleams. The exposed toggle switch is showing its age though. My recommendation is to get the pre amp with the RF sensing. My opinion is that there is no if you will inadvertantly transmit through it, just when.
73, Gould ----- Original Message ----- From: "Ted" [email protected] To: "'AMSAT BB'" [email protected] Sent: Wednesday, February 16, 2011 4:59 PM Subject: [amsat-bb] pre amp help..
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Hi Ted,
I have an ARR 160 watt RF sense unit and it works great. I also have a couple of SSB RF sense units and they work great too.
73, Tony AA2TX AMSAT VP Engineering
---
At 04:59 PM 2/16/2011, Ted wrote:
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK
As others, SSB Electronics model that is RF switched. I *have* transmitted 100+ watts into it, though not on purpose, and it works just fine. I got the RF switched model as a "just in case" bit of insurance, and am glad I did.
It's been reported here a few years ago that sometimes there's a little "burp" of RF that squirts out when a transceiver is powered up. Seems unlikely , but if so, maybe that did it?
If I recall, the discussion was about people frying their AO-40 S-band down converters by accidentally transmitting into them. An somewhat less certain recollection is that someone came up with a simple circuit that would clamp the RF to a more forgiving, if not totally safe level. As an alternative to an RF switched preamp model, perhaps a stroll through the archives might net a different solution.
Good luck,
Greg KO6TH
From: [email protected] To: [email protected] Date: Wed, 16 Feb 2011 13:59:41 -0800 Subject: [amsat-bb] pre amp help..
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I think DEMI made those "protectors". I never modified my K5GNA downconverter, so my FT-847 was tuned to 123MHz to use it, and it wouldn't transmit there. Jim
On 02/17/2011 05:56 AM, Greg D. wrote:
As others, SSB Electronics model that is RF switched. I *have* transmitted 100+ watts into it, though not on purpose, and it works just fine. I got the RF switched model as a "just in case" bit of insurance, and am glad I did.
It's been reported here a few years ago that sometimes there's a little "burp" of RF that squirts out when a transceiver is powered up. Seems unlikely , but if so, maybe that did it?
If I recall, the discussion was about people frying their AO-40 S-band down converters by accidentally transmitting into them. An somewhat less certain recollection is that someone came up with a simple circuit that would clamp the RF to a more forgiving, if not totally safe level. As an alternative to an RF switched preamp model, perhaps a stroll through the archives might net a different solution.
Good luck,
Greg KO6TH
From: [email protected] To: [email protected] Date: Wed, 16 Feb 2011 13:59:41 -0800 Subject: [amsat-bb] pre amp help..
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an alternative. Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
What Greg is describing is an RF sensed high-power attenuator. Downeast makes two products that can work to do this:
One is the AOS-144 ( $80.00) which switches RF thru a 50w attenuator to a factory adjusted level from 10 up to 100mw output for driving a transverter. The receive side is passed thru to a common SO-239 connector which is connected to the radio. To use it solely for a preamp a 50-ohm resistor can be tied across the BNC transmit output connector. This would be used in conjunction with TR relay for unswitched preamps like the P144VDG.
They also make the SSBT ( $65.00) safety switch bias-tee which might be more appropriate. It provides dc voltage to power the preamp over the coax line and senses RF for protection up to 50w. Again one would need TR relays for bypassing the preamp if you want to also use the antenna for transmitting.
But if you just want protection for a dedicated receive preamp either would work without need for a relay.
I know that 100w was mentioned, but these probably would withstand a momentary application of 100w such as the turn-on "burp" that some radios have. http://www.downeastmicrowave.com/cat-frame.htm
73, Ed - KL7UW
At 08:56 PM 2/16/2011, Greg D. wrote:
As others, SSB Electronics model that is RF switched. I *have* transmitted 100+ watts into it, though not on purpose, and it works just fine. I got the RF switched model as a "just in case" bit of insurance, and am glad I did.
It's been reported here a few years ago that sometimes there's a little "burp" of RF that squirts out when a transceiver is powered up. Seems unlikely , but if so, maybe that did it?
If I recall, the discussion was about people frying their AO-40 S-band down converters by accidentally transmitting into them. An somewhat less certain recollection is that someone came up with a simple circuit that would clamp the RF to a more forgiving, if not totally safe level. As an alternative to an RF switched preamp model, perhaps a stroll through the archives might net a different solution.
Good luck,
Greg KO6TH
From: [email protected] To: [email protected] Date: Wed, 16 Feb 2011 13:59:41 -0800 Subject: [amsat-bb] pre amp help..
I just sent my ARR pre amp back to ARR for repair for the 3rd time !
(pretty sure I did not tx through it )
What are people using for pre amps. I only see the Mirage as an
alternative.
Any other choices. I'm kind of disappointed in ARR products. Is there a pre amp that you can tx through preventing accidental frying?
Any thoughts appreciated
73, Ted, K7TRK _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
73, Ed - KL7UW, WD2XSH/45 ====================================== BP40IQ 500 KHz - 10-GHz www.kl7uw.com EME: 144-1.4kw*, 432-100w, 1296-testing*, 3400-winter? DUBUS Magazine USA Rep [email protected] ====================================== *temp not in service
participants (7)
-
Anthony Monteiro -
Edward R. Cole -
Gould Smith -
Greg D. -
Jim Jerzycke -
Stephen E. Belter -
Ted