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Reviews For: Racal RA6793

Category: Receivers: General Coverage

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Review Summary For : Racal RA6793
Reviews: 1MSRP: UNKNOWN
Description:
Premium general coverage HF receiver. Essentially a variant of the RA6790/GM (listed in Jane's Military Communications Systems as a surveillence / signal analysis receiver).
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0015
W9LBB Rating: 2002-09-13
A Racal with some Bells & Whistles Time Owned: 6 to 12 months.
Shortly after acquiring a Racal RA6790/GM (and very quickly becoming addicted to the excellence of Racal stuff), I had the opportunity to get hold of an RA6793, and after digging up all of the (limited) information I could find on the rig, I promptly jumped on it! I'm glad I did.

The RA6793 is very similar to the RA6790/GM in most ways (physically & electrically); the RA6793 is essentially a specialized version of it. MANY mechanical components and the majority of electrical subassemblies are interchangable between the two radios.

Performance of the two rigs is quite similar in most aspects. Rather than repeat all the stuff in the numerous reviews on this system of the RA6790/GM, I'd suggest that you to check out those reviews first, and then return to THIS one to find out about the differences and enhancements.

I will say this tho. My RA6790/GM consistently outperforms my RA6793 when it comes to sensitivity, and does so by a pretty fair margin. The difference seems to be that the RA6790/GM has the optional (and pretty scarce) RF preamplifier module, and the RA6793 doesn't. When the preamp is removed from the system, the two rigs are pretty much the same in sensitivity and noise figure.

Physically the receivers are pretty much identical. Both 3 rack units high, and appear to both use the same heavy chassis casting. Most of the sheet metal is identical.

The most obvious difference is the keypads. While the 6790/GM uses a pair of rather sturdy "membrane" keypads, the 6793 has a pair of real, honest to goodness mechanical keypads using Hall effect switches. They definitely feel a whole lot better and more positive than the membrane pads.

The LCD displays, at first glance, appear to be identical to those on the 6790/GM, but only the MODE display is. The FREQUENCY display is larger to show an extra line of information, relating to the reciever's memory options.

The rig has the capability to store in memory 100 frequencies with mode, AGC, and bandwidth settings, in ten banks of ten frequencies each.
They can be accessed in two different ways: (1) they can be read by rotating the main tuning dial, or (2) the banks can be scanned sequentially, at any of 10 user selectable rates.

Here there's a bit of a problem tho.

If a signal is present on a channel, the receiver keeps on scanning; there's no squelch in the 6793 to stop the scan (squelch circuits are pretty rare in AM receivers, and even harder to find in SSB rigs; there's no carrier for a squelch to work with!). Scanning must be stopped manually.

I can't vouch for it, but according to Jane's the RA6793A DOES have a squelch circuit, which I assume controls the scanning functions.

There seem to be options for this rig that aren't normally seen in the 6790/GM, and in some cases are apparently installed in place of the normal 6790/GM option boards and modules.

In mine I discovered that installed in the space reserved for the ISB board there is a panaramic adaptor output board, intended for watching activity on a wide stretch of spectrum on a scope. The output center frequency of this one is 21.4 MHz.

The RA6793 is every bit as impressive a receiver as the RA6790/GM is, and has a few special purpose tricks up it's sleeve besides. It's also a LOT more scarce and harder to find than the 6790/GM; when it IS available, there seems to be a rather steep premium on the price as compared to it's more common brother.

For advanced SWLs into playing specialized monitoring games (data modes especially), it's definitely a winner. I would, however, suggest that if possible you get for the A version.


Anybody know where I can lay my hands on another RF preamp module???


73's

Tom, W9LBB