[Collins] PRC-47

[WF2U]

I don't have a PRC-47 to sell, but I have one I use once in a while.

The PRC-47 is USB only. There are 2 ways of modifying it for LSB: a.
swapping the mechanical filter to the opposite sideband filter of the same
type - they're available.
b. you can squeeze the other filter in as well and provide switching with
submini relays - downside is that the sideband selector switch has to be on
the front pane, most people don't want to drill a hole in the front panel
and deface it. The dial light switch in this case can be wired for sideband
selection.

One big problem is the 24VDC input to 115 VAC 400 Hz inverter (unless you
have a 115 VAC 400 Hz power source in which case you don't need to power it
up from the 24 VDC option). The chopper transistors are germanium and almost
invariably when you turn on the radio which had been stored for years, - but
also just randomly, even it was recently used - they go POOF. The germanium
transistors by nature change their characteristics over time unlike silicon
devices and it's a matter of time when they become bad. New germanium
replacements (NTE) are available but expensive. Most PRC-47 users change the
chopper transistors to cheap, much heavier duty silicon devices in the same
case, like the Rat Shack 3035 type and its complementary NPN version.
Silicon devices will need a modification in the biasing circuit in the
inverter, but they'll last a long time.

The rating of 100 W PEP output in the high power position for very short
time only. In fact it's not advisable to run it in high power at all. The
final tube is not really cooled in any way. There is an RTTY kit which
mounts on the front panel over the access hatch to the final, and it has a
small blower. The blower is a good way to keep the rig healthy.

73, Meir WF2U / NNN0AAF
Landrum, SC

> -----Original Message-----
> From: collins-bounces at mailman.qth.net
> [mailto:collins-bounces at mailman.qth.net]On Behalf Of BSugarberg
> Sent: Tuesday, May 02, 2006 10:57 PM
> To: collins at mailman.qth.net
> Subject: [Collins] PRC-47
>
>
> Hello,
>
> Does anyone have a PRC-47 they would like to sell?
>
> What are the pros and the cons of the PRC-47?
>
> Are there any good articles on the PRC-47?
>
> Are there any good mods for the PRC-47?
>
> Is there a PRC-47 users group?
>
> Thank you,
>
> Bruce WA8TNC
>
>
>
>
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