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Re: How to connect DC to ARR preamp or dc injector?



Hi, Jeff,

<<MAYBE YOU COULD HELP ME, I HAVE UHV/VHF/FM TV PREAMP. RADIO SHACK MODEL 15 1113B. I WANT TO HOOK IT UP TO MY UHF KLM ANT AND SEE IT HELPS BRING IN AO-51 DATA/TLM. IT HAS A INPUT AND OUTPUT. ANT. END GOES IN THE INPUT? OUTPUT GOES TO THE RIG? YES I KNOW I CANT XMIT WHILE ITS HOOKEDUP.>>

That's about the same question I was asking the group.  Yes, I'd assume that the downlink signal gets fed into the preamp INPUT and the boosted signal goes to your receiver's antenna input from the preamp OUTPUT.  You want to connect +DC to the preamp at a jack or some other bit of hardware that might be labeled something like Vdc in or the like, and the (-) lead from your battery or DC power supply to a jack or the like on the preamp labeled maybe like "Gnd" (ground.)  That's the way the preamp I now have is labeled, there is no single coaxial jack for the power connection, the (+) and (-) inputs are on opposite sides of the preamp case.

I was just looking for advice on specifically how others connect the (+) and (-) leads from their respective power supplies to their preamps, or in my case, their bias-tees.  Directly soldering the lead ends to the feed-through and ground lug, or via some type of removable/unpluggable affair?  What about a fuse?  Does ARR put one in their preamps or bias-tees, or do I need to fuse the DC line from my battery/PS on my own?

I have this bare nubbin-like bit of thick wire coming out, to which I'm supposed to attached +Vdc; how do I form a good electrical AND mechanical connection to it?  The lug on the gnd side looks pretty academic, so I don't anticipate problems.  Why didn't ARR just build these things with a coax DC input jack?  Does a design like that not lend itself well to the inclusion of a DC feedthrough cap?

BTW, in response to at least one reply to my initially-posted query, the preamp in question is a P432VDG, good for 420 - 450, has a .5Nf, advertised as offering 17dB gain, +12 dBm 1dB comp and a 1db BW of 40MHz.

Anyhow, I'm perplexed.  Jeff, I hope what I've offered helps.  You may also need some RF adapters to mate your preamp, which sounds like it's designed to operate with F type connectors and RG-59 75ohm TV cable, to the BNC or N type connector hardware you'd expect to see on UHF amateur gear.  In the end, it may not work at all because of a host of factors common to UHF circuits about which I'm only now learning myself.  Gud Luck to you, too.  When you determine any success, you should post to the bb, too, and put out your findings.

Very 73,
Ray KA8SYX
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