Adding a Pre-amp to a standard tranciever
I am considering my next station upgrade to be mast mounted preamp(s). I prefer the NON R.F. switching type due to their general better performance/cost and leaving me the ability to run QRO is need be in the future. My only experience is using a preamp with a transverter where there are seperate RX and TX lines. Now I do fully understand that you cannot TX threw these devices. My radio DOES have the ability to send DC voltage threw the coax while recieving ( IC 820H ). Even tho the radio can do this, I just dont understand how it works or if I would still need to use a sequencer. And even at all that... how an ARR preamp ( example ) can pass any sort of RF. The only way I can see how it would work is if some sort of switch is inplace @ the antennas as well, the DC from the radio or sequencer switches the preamp IN place when RX'ing and OUT of place when TX'ing. Now if this is indeed the case.. and im going to assume it is.. where would I begin to look for a Coaxial Relay that can pass 1kw @ 432 / 144 mhz? Now I know your thinking HU? 1KW!!! This is not my intended power level for the sats.. dont worry.. its for ( in the future ) possibly trying some single or dual yagi EME.
-Steve Raas N2JDQ FN20vg
At 11:35 PM 2/3/2007 +0000, sraas@optonline.net wrote:
I am considering my next station upgrade to be mast mounted preamp(s). I
prefer the NON R.F. switching type due to their general better performance/cost and leaving me the ability to run QRO is need be in the future.
My only experience is using a preamp with a transverter where there are
seperate RX and TX lines. Now I do fully understand that you cannot TX threw these devices. My radio DOES have the ability to send DC voltage threw the coax while recieving ( IC 820H ). Even tho the radio can do this, I just dont understand how it works or if I would still need to use a sequencer. And even at all that... how an ARR preamp ( example ) can pass any sort of RF. The only way I can see how it would work is if some sort of switch is inplace @ the antennas as well, the DC from the radio or sequencer switches the preamp IN place when RX'ing and OUT of place when TX'ing.
Now if this is indeed the case.. and im going to assume it is.. where
would I begin to look for a Coaxial Relay that can pass 1kw @ 432 / 144 mhz? Now I know your thinking HU? 1KW!!! This is not my intended power level for the sats.. dont worry.. its for ( in the future ) possibly trying some single or dual yagi EME.
-Steve Raas N2JDQ FN20vg
Steve,
I'm not sure if the above is directed to answer what I wrote you. I made no comments about transmitting on the coax line leading to the preamp (NOT something you want to do). MY comments had to do with sending DC voltage up the coax to power the preamp.
Since your IC-820H has the capability for sending dc power up to the preamp, you only need a way to separate out the voltage at the preamp. This is typically done with a coupling capacitor in line with the center conductor and an RF choke taking dc off the center conductor to the power input lead.(internally). Commercially they are called Bias-T's. This does not require a sequener. If you plan to transmit on the same cable, then one should think about getting a sequencer, coax T/R relay, and separating your Tx and Rx lines.
ARR makes an automatic switching preamp that allows one to transmit on the same line. They detect RF power and do the switching internally. They also power the preamp thru the coax line. BUT NOT ALL ARR preamps have this ability. You can go to the advanced receiver website and determine if you have that model.
Hope this clears up everything.
Ed
73's, Ed - KL7UW ========================================= http://www.qsl.net/al7eb - BP40iq 144-EME: FT-847, mgf-1801, 4xM2-xpol-20, 185w (QRV) 432-EME: Not QRV USA Rep. for Dubus Magazine: dubususa@hotmail.com =========================================
My ARR preamp uses RF sensing circuitry and a relay to switch itself out of the line when transmitting. It's good to 160 watts. I know that this isn't what you want but it seems to me that there is still a way to employ a sequencer with it for other applications. I got literature with it that stated as much, although I can't place my hands on it now. One thing I will mention is that if you wish to power an ARR preamp through the coax, you have specify this to them when you order it. They then install the necessary parts at the amp end. Otherwise it's designed to be powered seperately through a military spec. connector which they supply. Don't know if this helps but since I have your example brand of pre-amp I thought I'd chime in. 73, Michael, W4HIJ
At 11:35 PM 2/3/2007 +0000, sraas@optonline.net wrote:
I am considering my next station upgrade to be mast mounted preamp(s). I
prefer the NON R.F. switching type due to their general better performance/cost and leaving me the ability to run QRO is need be in the future.
My only experience is using a preamp with a transverter where there are
seperate RX and TX lines. Now I do fully understand that you cannot TX threw these devices. My radio DOES have the ability to send DC voltage threw the coax while recieving ( IC 820H ). Even tho the radio can do this, I just dont understand how it works or if I would still need to use a sequencer. And even at all that... how an ARR preamp ( example ) can pass any sort of RF. The only way I can see how it would work is if some sort of switch is inplace @ the antennas as well, the DC from the radio or sequencer switches the preamp IN place when RX'ing and OUT of place when TX'ing.
Now if this is indeed the case.. and im going to assume it is.. where
would I begin to look for a Coaxial Relay that can pass 1kw @ 432 / 144 mhz? Now I know your thinking HU? 1KW!!! This is not my intended power level for the sats.. dont worry.. its for ( in the future ) possibly trying some single or dual yagi EME.
-Steve Raas N2JDQ FN20vg
Several issues with mast mounted preamps include protection from the elements , dew forming on the parts and having a electro mechanical device at the antenna that can fail. With the gain of the preamp use of a higher loss cable for receive is possible reducing the number of relay contacts used. RF switching back to eceive is limited to the delay time needed when SSB TX mode is used. Solid state switching does not like to handle 100's of watts. Preamps will not handle more that mW! All of these problems are manageable, but a run of Andrews 7/8 low loss hard line really starts to look like an atractive option.
This is what makes design of a station a challenge: What must I give up to get what I want? Trade offs are just part of life, we make our choices and the laws of physics tell us the consequences!
Art, KC6UQH
----- Original Message ----- From: "Michael Tondee" mat_62@netcommander.com Cc: AMSAT-BB@amsat.org Sent: Saturday, February 03, 2007 5:57 PM Subject: [amsat-bb] Re: Adding a Pre-amp to a standard tranciever
My ARR preamp uses RF sensing circuitry and a relay to switch itself out of the line when transmitting. It's good to 160 watts. I know that this isn't what you want but it seems to me that there is still a way to employ a sequencer with it for other applications. I got literature with it that stated as much, although I can't place my hands on it now. One thing I will mention is that if you wish to power an ARR preamp through the coax, you have specify this to them when you order it. They then install the necessary parts at the amp end. Otherwise it's designed to be powered seperately through a military spec. connector which they supply. Don't know if this helps but since I have your example brand of pre-amp I thought I'd chime in. 73, Michael, W4HIJ
At 11:35 PM 2/3/2007 +0000, sraas@optonline.net wrote:
I am considering my next station upgrade to be mast mounted preamp(s). I
prefer the NON R.F. switching type due to their general better performance/cost and leaving me the ability to run QRO is need be in the future.
My only experience is using a preamp with a transverter where there are
seperate RX and TX lines. Now I do fully understand that you cannot TX threw these devices. My radio DOES have the ability to send DC voltage threw the coax while recieving ( IC 820H ). Even tho the radio can do this, I just dont understand how it works or if I would still need to use a sequencer. And even at all that... how an ARR preamp ( example ) can pass any sort of RF. The only way I can see how it would work is if some sort of switch is inplace @ the antennas as well, the DC from the radio or sequencer switches the preamp IN place when RX'ing and OUT of place when TX'ing.
Now if this is indeed the case.. and im going to assume it is.. where
would I begin to look for a Coaxial Relay that can pass 1kw @ 432 / 144 mhz? Now I know your thinking HU? 1KW!!! This is not my intended power level for the sats.. dont worry.. its for ( in the future ) possibly trying some single or dual yagi EME.
-Steve Raas N2JDQ FN20vg
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participants (4)
-
Edward R. Cole -
kc6uqh -
Michael Tondee -
sraasï¼ optonline.net