From: "VE3AX" 
Subject: Re: [drakelist] AM Filter Advice for TR-7


"VE3AX"  made an utterence to the drakelist gang
----------------------------------------------------------------------
Jim:

Garey has given you very good advice.

While you are in there, I'd check the PIN diodes as well.  There are two on
the front HPF board that look like two lead transistors.  You can check them
with an ohmmeter.  The three on the rear HPF board are high power PIN diodes
and are a little more difficult to get at to check but you can get a good
idea if there is a problem with them by checking the two DC pins near the
top of the board.  One gives essentially zero volts on rx and the other is
+12VDC on rx; on tx they switch.  You should not see any more than 0.3 volts
or so on the "low" reading.  If you get, say, +12 on tx and +4 on rx there
is a problem.  Of course the other "symptom" of bad PIN diodes is low power
output on 15 and 10 meters.

My 1st TR7 had weak AM broadcast spurs all across the bands right up through
28 Mhz with one bad PIN diode.

I have two TR-7's with the 390 ohm resistor in the AM filter position and it
works just fine.
I don't see a lot of difference between those two and the two with the AM
filters.

73

Peter
VE3AX


----- Original Message -----
From: "Jim DiMauro" 
To: "Drakelist" 
Sent: Saturday, January 01, 2005 11:17 PM
Subject: RE: [drakelist] AM Filter Advice for TR-7


>
> "Jim DiMauro"  made an utterence to
the drakelist gang
> ----------------------------------------------------------------------
> Many thanx to all who responded.  I'm going to start by checking the
shields
> tomorrow morning.  I'll let the group know what I find.  Also, thanx for
the
> input on filter sources.  If I'm going to spend nearly $100 for a filter,
> it's going to be a new one.  Since there's no clear winner out there among
> filter suppliers, I'll liok at Inrad and Sherwood, who both offer filters
> for the TR-7.  But first, the shields & grounds...
>
> 73,
> Jim
> WA2MER
>
> -----Original Message-----
> From: owner-drakelist{at}www.zerobeat.net
> [mailto:owner-drakelist{at}www.zerobeat.net]On Behalf Of Jim Shorney
> Sent: Saturday, January 01, 2005 5:55 PM
> To: Drakelist; jfd{at}warwick.net
> Subject: Re: [drakelist] AM Filter Advice for TR-7
>
>
>
> "Jim Shorney"  made an
utterence to the drakelist
> gang
> ----------------------------------------------------------------------
> On Sat, 01 Jan 2005 16:16:54 -0500, Garey Barrell wrote:
>
> >Something else is going on if you are hearing a signal that is 45 kHz
away!
> >
> >Unless you are living next to CHU and listening to a QRP signal from
> >Tibet, something else is wrong!  You don't have the calibrator switched
> >on do you?  Or the RV-7/75 external PTO?  Is the card cage shield in
> >place with ALL screws?   DO you live under the CHU tower?  :-)
>
> Maybe bad filter capacitors on the DC-DC converter board? I could QSO
> on three different frequencies at once when my TR7 had this disease.
> Potentially handy, but it didn't do much for RX performance in a
> crowded band. Check to see if you can recieve a strong signal about 23
> KHz above and/or below the true frequency.
>
>
>
> --
> Jim Shorney      -->.<--Put complaints in this box
> jshorney (at) inebraska.com
> nu0c (at) amsat.org
> Ham Radio NU0C
> Lincoln, NE, USA
> EN10ps
> http://incolor.inetnebr.com/jshorney/
>
> ----------------------------------------------------------------------
> On Behalf of "Jim Shorney" 
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