Thanks Don for your prompt reply.
I built it a few years ago and I think it worked then. I just got back
into UHF and thought to check it out. So, I am not sure if it worked
before.
I have peaked the RX cap and LNA bias.
I measured the gain across the ATF to be 10.5dB. Does that indicate
that the PHEMT needs to be replaced?
Raj, N2RD
------ Original Message ------
From: "Don Wilhelm" <donw...@embarqmail.com>
To: "Rajiv Dewan" <rdew...@rochester.rr.com>; Elecraft@mailman.qth.net
Sent: 5/12/2019 2:03:48 PM
Subject: Re: [Elecraft] XV432 deaf
Raj,
Has this XV432 worked before and recently developed weak receive? If so, try
peaking the RX input capacitor, and if that does not correct it, replace the
PHEMT (ATF34143).
If you recently acquired it, check the configuration jumpers for the 28 MHz IF
- do you have a single coax and it is configured for separate TX and RX IF (or
vice-versa)?
73,
Don W3FPR
On 5/12/2019 1:44 PM, Rajiv Dewan wrote:
Dear all,
I have a XV432 that seems deaf compared to my ICOM IC-7000. When I tune to
a local beacon on 432.300 MHz, I can copy it clearly on the IC but nothing is
heard on the XV432/K3 with KXV3B. I checked transverter set up by feeding it a
signal from a signal gen. It has a conversion gain of about 16 to 17dB. The
specs say 20dB. This does seem to be too bad.
I checked the front end RF circuit out by feeding in a -80dBm signal from
HP8657B signal generator set to 432.300MHz. The ATF34143 seems to have a net
gain of 11dB. The next MMIC MAV11 seems to have a gain of 10.5dB. Are these
within spec?
If I can fix it without altering the circuit, that would be ideal.
Else, I am considering two mods:
Replace the MAV11 (10 to 12db gain in specs) with MAR8 (27dB gain) with
appropriate change in the bias resistor (120 1W to 270 ohms 1/4W)Insert a W6PQL
LNA (uses PGA103+) between K10 and the ATF on board.
Thoughts/ideas are very welcome,
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