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Panadaptors for the R390 page 3

That's quite true, and especially in the light of the understated manual. Typically they give

a laconic instruction "...remove the 2nd VFO..." which translates to half a day of cussing,

unsoldering and contortions. In addition, the "Hunts" brand of capacitors in the RA-17

make Black Beauties look like mil-spec space rated lab standards in comparison.

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Date: Mon, 13 Dec 1999 19:28:15 -0600

From: "Jon & Valerie Oldenburg" <[email protected]>

Subject: Re: [R-390] Panoramic adapter hookup question

I have this responce from the group a while back Jon KB9VFD: 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

beimportant. 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: Mon, 20 Mar 2000 10:38:06 +0000

From: "B.L.Williams" <[email protected]>

Subject: [R-390] panadapter problems

I found a Heathkit SB-620 a few weeks ago and bought it. Very nice looking with very

good work done on the chassis. I think it is wired for 455 kHz and have checked out the

manual pretty closely. There is at least one change on the scope from the manual in the

coil wiring but basically it has to be 455 kHz. The only problem was something rolling

around inside the scope when I unpacked it. Took out the chassis and found a Motorola

0.1 MFD/1000v cap rolling around. It sure looked dirty and grungy with the worst

soldering job I've ever seen on the leads. The parts in the scope looked new and shiny. I

checked all the caps and none are Motorola and none are wax sealed like this spare cap.

The cap really looks filthy. So, after going over the manual a lot of times searching for

where this cap would go I found nothing. The parts list does not have this cap listed.

And, all of the solders are very good, shiny, and done quite well as opposed to the crusty

blobs on the spare cap. I just couldn't find any point on the scope where the cap could

have been tacked on. After many hours of searching around the manual and board I

became confident that it was either a mod or a cap tossed in for a spare. I've done that

myself but I tape the parts down good with notes as to what they are for. Judging the

cruddy solder job I decided that maybe some careless person was being careless again. I

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