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jury rigged vhf receiver
I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF
radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie |
jury rigged vhf receiver
JIMMIE wrote:
I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie For best performance these mixers require a constant impedance at all three ports (usually 50 ohms). The preamp will provide this for the RF input and the output of your HP signal generator should have a 50 ohm selectable output. You may need to add an attenuator between the generator and the mixer if the HP does not provide a 50 ohm termination using a variable output. You will need to set the oscillator injection level to the mixers required 7dbm drive level for best conversion "gain". The output should go through a bandpass filter covering the IF frequency you are down converting to and provide a 50 ohm impedance. A duplexer network here is a good idea (provides a 50 ohm termination at the IF frequency and a low impedance (short) to ground to out of IF signals). |
jury rigged vhf receiver
On Jan 23, 6:43*pm, Kenneth Scharf wrote:
JIMMIE wrote: I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie For best performance these mixers require a constant impedance at all three ports (usually 50 ohms). *The preamp will provide this for the RF input and the output of your HP signal generator should have a 50 ohm selectable output. *You may need to add an attenuator between the generator and the mixer if the HP does not provide a 50 ohm termination using a variable output. *You will need to set the oscillator injection level to the mixers required 7dbm drive level for best conversion "gain". *The output should go through a bandpass filter covering the IF * frequency you are down converting to and provide a 50 ohm impedance. A duplexer network here is a good idea (provides a 50 ohm termination at the IF frequency and a low impedance (short) to ground to out of IF signals). Any reccomendation on the best mixer to use? Jimmie |
jury rigged vhf receiver
JIMMIE wrote:
On Jan 23, 6:43 pm, Kenneth Scharf wrote: JIMMIE wrote: I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie For best performance these mixers require a constant impedance at all three ports (usually 50 ohms). The preamp will provide this for the RF input and the output of your HP signal generator should have a 50 ohm selectable output. You may need to add an attenuator between the generator and the mixer if the HP does not provide a 50 ohm termination using a variable output. You will need to set the oscillator injection level to the mixers required 7dbm drive level for best conversion "gain". The output should go through a bandpass filter covering the IF frequency you are down converting to and provide a 50 ohm impedance. A duplexer network here is a good idea (provides a 50 ohm termination at the IF frequency and a low impedance (short) to ground to out of IF signals). Any reccomendation on the best mixer to use? Jimmie Here's one good to about 600 MHz. Been used a gazillion times in just about all VHF/UHF transverters at one time or another. If casual listening is all you need, hook it up just like you said...VHF/UHF antenna to the RF port, HP signal generator to LO port (set to +7 dBm output for this mixer and frequency appropriate for your IF frequency such as 116 MHz for 144 MHz to be 28 MHz out of the mixer) and connect the mixer IF pin to your HF radio antenna port. Probably a good idea to use capacitor coupling at each mixer port, something like 1000pF should work. http://www.minicircuits.com/pdfs/TUF-1+.pdf Scott N0EDV |
jury rigged vhf receiver
JIMMIE wrote:
I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Just as an experiment, I once used the mixer & LO in one of my FM rigs. Just tapped the output of the mixer just before the IF filter, ran it through a DC-blocking capacitor out to the antenna input of a general-coverage HF receiver. Tuned the HF rig to 10.7MHz - sure enough, there were the 2m SSB (and CW) signals. Worked pretty well. It was pretty cumbersome to tune though. Luckily, almost everyone around here is within 5KHz of 144.200... Didn't take long to get the urge to transmit, at which point I wimped out & bought a multimode rig... -- Doug Smith W9WI Pleasant View, TN EM66 |
jury rigged vhf receiver
sorry-spammers wrote:
Luckily, almost everyone around here is within 5KHz of 144.200... "Lucky" depends on how many locals there are ;) If you have 10 or 20 local weak signal VHFers, it could get a bit messy ;) Scott, N0EDV EN45fa |
jury rigged vhf receiver
Scott wrote:
JIMMIE wrote: On Jan 23, 6:43 pm, Kenneth Scharf wrote: JIMMIE wrote: I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie For best performance these mixers require a constant impedance at all three ports (usually 50 ohms). The preamp will provide this for the RF input and the output of your HP signal generator should have a 50 ohm selectable output. You may need to add an attenuator between the generator and the mixer if the HP does not provide a 50 ohm termination using a variable output. You will need to set the oscillator injection level to the mixers required 7dbm drive level for best conversion "gain". The output should go through a bandpass filter covering the IF frequency you are down converting to and provide a 50 ohm impedance. A duplexer network here is a good idea (provides a 50 ohm termination at the IF frequency and a low impedance (short) to ground to out of IF signals). Any reccomendation on the best mixer to use? Jimmie Here's one good to about 600 MHz. Been used a gazillion times in just about all VHF/UHF transverters at one time or another. If casual listening is all you need, hook it up just like you said...VHF/UHF antenna to the RF port, HP signal generator to LO port (set to +7 dBm output for this mixer and frequency appropriate for your IF frequency such as 116 MHz for 144 MHz to be 28 MHz out of the mixer) and connect the mixer IF pin to your HF radio antenna port. Probably a good idea to use capacitor coupling at each mixer port, something like 1000pF should work. http://www.minicircuits.com/pdfs/TUF-1+.pdf Scott N0EDV For what it's worth, that's the same mixer used in the Elecraft K2 receiver section. |
jury rigged vhf receiver
On Jan 24, 10:51*am, Kenneth Scharf wrote:
Scott wrote: JIMMIE wrote: On Jan 23, 6:43 pm, Kenneth Scharf wrote: JIMMIE wrote: I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie For best performance these mixers require a constant impedance at all three ports (usually 50 ohms). *The preamp will provide this for the RF input and the output of your HP signal generator should have a 50 ohm selectable output. *You may need to add an attenuator between the generator and the mixer if the HP does not provide a 50 ohm termination using a variable output. *You will need to set the oscillator injection level to the mixers required 7dbm drive level for best conversion "gain". *The output should go through a bandpass filter covering the IF * frequency you are down converting to and provide a 50 ohm impedance. A duplexer network here is a good idea (provides a 50 ohm termination at the IF frequency and a low impedance (short) to ground to out of IF signals). Any reccomendation on the best mixer to use? Jimmie Here's one good to about 600 MHz. *Been used a gazillion times in just about all VHF/UHF transverters at one time or another. *If casual listening is all you need, hook it up just like you said...VHF/UHF antenna to the RF port, HP signal generator to LO port (set to +7 dBm output for this mixer and frequency appropriate for your IF frequency such as 116 MHz for 144 MHz to be 28 MHz out of the mixer) and connect the mixer IF pin to your HF radio antenna port. *Probably a good idea to use capacitor coupling at each mixer port, something like 1000pF should work. http://www.minicircuits.com/pdfs/TUF-1+.pdf Scott N0EDV For what it's worth, that's the same mixer used in the Elecraft K2 receiver section.- Hide quoted text - - Show quoted text - Thanks all , I found some little boxes in my scrap pile withe 3 SMA connectors on each one. Plan is to get a couple or 3 of the mixers and mount them in the boxes. Having a mixer in a box may be fun to play with. Jimmie |
jury rigged vhf receiver
On Jan 24, 10:03*am, sorry-spammers ""w9wi\"@(sorry-spammers)"
wrote: JIMMIE wrote: I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Just as an experiment, I once used the mixer & LO in one of my FM rigs. *Just tapped the output of the mixer just before the IF filter, ran it through a DC-blocking capacitor out to the antenna input of a general-coverage HF receiver. *Tuned the HF rig to 10.7MHz - sure enough, there were the 2m SSB (and CW) signals. *Worked pretty well. It was pretty cumbersome to tune though. *Luckily, almost everyone around here is within 5KHz of 144.200... Didn't take long to get the urge to transmit, at which point I wimped out & bought a multimode rig... -- Doug Smith W9WI Pleasant View, TN *EM66 Thats a thought, I might do that with an old mobile unit I have in the junk box. I think it will rx but the tx is dead. See if I can pick the signal off right after the first mixer. Jimmiej |
jury rigged vhf receiver
On Sat, 23 Jan 2010 14:52:14 -0800, JIMMIE wrote:
I was wanting to listen to VHF/UHF SSB. All of my present UHF/VHF radios are FM. I was thinking of rigging up a simple downconverter using a mini circuit mixer and my HP signal generator as the local oscilator that I can connect in front of my HF rig. I have an antenna mounted pre- amp that I think should suffice for my front end. Any foreseeable problems short of keying my transmitter while it is connected. Jimmie Performance won't be optimal, and you'll get some LO leakage. You may want to consider trapping the LO back toward the antenna, or using a preamp just to block the radiation. Or just lash the dang thing together and see how it works. -- www.wescottdesign.com |
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