[Central-Electronics] Carrier supression on CE100V

[Fallon, Joseph]

Hi George,

The 1N5711 has a higher value of Cj (2.0 vs. 0.8pF) and much lower leakage current (0.2 vs. 100 uA @Vr =50) when compared to the 1N270. It looks like the Vf is higher for the 1N5711 (Vf = 1 V @ If of 15mA vs. 200mA)  Not sure if the higher Cj would significantly impact the operation of the balanced modulator.

I am looking at the 8Mhz output of the modulator when measuring the carrier suppression.

Joe WA1IWQ

From: George Maier [mailto:george at maiergroup.com]
Sent: Tuesday, January 29, 2013 1:06 PM
To: Fallon, Joseph
Cc: central-electronics at mailman.qth.net
Subject: Re: [Central-Electronics] Carrier supression on CE100V

Well Joe, it sounds like you should be seeing over 40 dB, and closer to the original spec of 50.  On the other hand,  I've never used Schottky diodes in a CE
Exciter, and don't know what to expect.  Perhaps someone else on the reflector has.
Having said that, I don't normally use 1N34A's either, preferring 1N270's instead. They're really close to 1N34's as a modulator, but a lot more robust in the current handling department.
You might try measuring the carrier balance right at the modulator to eliminate non-linearities in the rest of the chain making it look worse.

73, George- W1LSB
Sent from my Verizon Wireless 4G LTE DROID


"Fallon, Joseph" <joe.fallon at philips.com<mailto:joe.fallon at philips.com>> wrote:

Hi George,

I used 1n5711 Schottky  diodes that I matched the Vf to less the 1%.  The caps were replaced with 10uF, 50V electrolytics with 20% tolerance.

73’s

Joe WA1IWQ

From: George Maier [mailto:george at maiergroup.com]
Sent: Tuesday, January 29, 2013 9:51 AM
To: Fallon, Joseph
Cc: central-electronics at mailman.qth.net<mailto:central-electronics at mailman.qth.net>
Subject: Re: [Central-Electronics] Carrier supression on CE100V

Hi Joe:
Did you match the diodes and caps?
73, George- W1LSB

Sent from my Verizon Wireless 4G LTE DROID


"Fallon, Joseph" <joe.fallon at philips.com<mailto:joe.fallon at philips.com<mailto:joe.fallon at philips.com%3cmailto:joe.fallon at philips.com>>> wrote:

Hi Folks,

    Anyone know the typical spec for the carrier suppression of the CE100V?  Replaced the Mod diodes and Caps, tweaked  the 8MHz osc and I'm seeing about 35db which still seems to be on the low side?

    Tnxs,

    Joe WA1IWQ


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