Panadaptors for the R390 page 2
intended for airborne use with the Hallicrafters built ARR-7, a repackaged and modified
version of the SX-28 Super Skyrider, which includes UHF series connectors on the front
panel for panadaptor connection. Tom, W9LBB
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Date: Mon, 16 Mar 1998 08:04:20 -0500 (EST)
Subject: Re: [R-390] Panadaptors and the R-390
The navy version was RBU-1 for various receivers.... It was designed for the
RBA/RBB/RBC series with 400 KHz intermediate frequency. Uses inverse filtering to
equalize the pan display for the receiver filtering. And the RBA/B/C on broad are pretty
darn broad....
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Date: Thu, 26 Aug 1999 10:28:21 +1000
Subject: Re: [R-390] Panadapters
You can't see a full 1 MHz at 455 KHz so if you're using a 455 KHz panadaptor you'll
only get 30-50 Khz or so. Just wrap a little bit of wire around the plate pin of the 3rd 6C4
mixer (the one that feeds the IF strip, I don't have the tube designation handy). Put a 0.01
600V blocking cap and 47K resistor in series with it and feed it out through coax to your
panadaptor. I use a Singer SA-8B and it works very well. Panadaptors have their own
specs regarding capacitance at the input - it's usually part of a tuning network so the length
of coax may be important. From the point of view of the R-390A you want to isolate it
and keep the effect of cable capacitance as low as possible, hence the resistor.
If you want to look at a full 1 MHz you'll have to get the 2-3 MHz signal before the 3rd
mixer (ie: before the PTO signal is mixed with it) and use either a special panadaptor (I
don't know if such a beast exists for the R-390A - the RA-66 panadaptor for the Racal
RA-17 works that way but it's more complicated than the receiver itself!) or a spectrum
analyzer.
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Date: Thu, 26 Aug 1999 11:27:58 +1000
Subject: Re: [R-390] Racal receivers
>As much as I love my R390A, I'm very impressed with the ease and beauty >of
bandscanning with the Racal receiver. ...........
Just so - the R-390A is ideal if you know where you want to be and want to stay there.
It's more sensitive than the RA-17 and less noisy - the RA-17 uses the world's noisiest
mixer tube (6BE6) for the 3rd mixer and E180F pentodes for the first two which are not
much quieter. The RA-17 is a great bandcruiser though, and looks nice. It's matching
panadaptor is an anchorite's dream.
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