You should be able to change the front end switching diodes to PIN diodes. A
1N5767 should do the trick. Make sure that they are biased up to at least
15mA.

Pete

"Mark Zenier" wrote in message
...
In article . com,
wrote:
Recently I picked up an R-1000 in nice condition, and did a search in
this newsgroup, the feeling seems to be that this is basically a decent
receiver with good audio but prone to overloading with a large antenna.

I have a couple of commercial shortwave antennas which I could use when
I get time to put them up, both being about 50' in length, though one
can be shortened if need be. I like to listen to the major
broadcasters but also enjoy touring the 60 meter band for Africans as
well. Can anyone suggest an antenna length that would be best for this
receiver?

There's a ton of diodes in the front end (it uses diode switched
bandpass filters), so if you put too much antenna on it, it's
prone to amazing amounts of intermod from nearby medium wave stations.
I found that 200 feet was too much, as I'm 5 miles from Seattle's
medium wave farm on Vashon Island. About 60 feet seems ok.

Also, you can try running it into the 50 ohm coax plug instead of the
500 ohm push terminal, (and remember to flip the back panel switch ;-) )
, without the matching transformer it's less prone to overload.

I found that, when I bought a FR-200 portable to play with, that
the R-1000 will reradiate this intermod when it's turned off and the
diodes in the front end are unpowered.

Would the attenuator lose too much signal, or make it an
ideal situation? Testing with a short wire wiped out all but the
strongest signals, and even they weren't enjoyable then.

The 20 dB step on the attenuator makes it useless. There's a mod
on the mods.dk site for changing a bunch of resistors to make it 10
dB per step.

Also, the 12 kHz filter in this radio sounds great on clear mediumwave
stations, are there any shortwave stations that have clear signals and
good audio which I can use this wide filter with (I've been away from

No, not really. That's why there's the plug/cable setup where you
can select for two different selections of wide and narrow for the
front buttons. Plugging the three wire harness (at the mddle of the
top board) into one socket sets it to 2.1/SSB/6narrow/12wide, the other
2.1ssb/2.1narrow/6wide. (I cheat. I came up with a circuit mod using a
CMOS analog switch IC that let's me get all three bandwidths for any
mode by pushing in 1,2 or 3 buttons at the same time.)

There is also an audio bandwidth spoiler circuit that narrows the
bandwidth when the AM-nar button is pressed (or widens it when the
AM-Wide is in) regardless of the other configuration. This, I think,
could be defeated by popping the connector terminal on one of the top
board plugs, but I've never bothered to try that. (Likewise, there's
an RF gain spoiler circuit that lowers the sensitivity below 2 MHz.)

Both the operation and repair manuals are on the mods.dk web site.

the hobby for a while)? Is the excellent audio reputation of the
R-1000 from the stock wide filter alone, or is the entire audio circuit
what makes it so good? If its just the stock filter, wouldn't any
receiver benefit greatly from something wider than the standard 6 kHz
filter in the wide slot?

I'd go with the filter bandwidth. I'm not impressed with the built in
amp and speaker. Not in the same league as an R-5000. You do get pretty
good stuff out of the front panel "record" jack, but it's not the
ultimate AM receiver.

Mark Zenier Washington State resident