[HomeBrew] 72 MHz amp

[R. Blackman]

Thanks to all who replied to my post. I will try your suggestions.
As to the particulars,
All caps are mono, resistors are carbon/ceramic (I think),
Test equipment consists of a homebrew dedicated 72 MHz oscillator, 2v p-p,
BK Precision  rf signal generator,
HP 1741A 100 MHz dual trace scope,
HP variable power supply 0-20v @ 30 amps
All component values checked with a AADE  L/C meter
and  a Waveteck DVDM volt /ohmmeter

Again, thanks  and I will report back.
/Richard VA3NDO
----- Original Message ----- 
From: "km1h" <km1h at jeremy.mv.com>
To: "R. Blackman" <richard.blackman at sympatico.ca>; "HOMEBREW" 
<homebrew at mailman.qth.net>
Sent: Sunday, November 28, 2004 3:22 PM
Subject: Re: [HomeBrew] 72 MHz amp


> First of all are you absolutely sure of the component values? Also at 
> those frequencies I use nothing but quality monolithic caps and carbon 
> film resistors. Mouser is my usual source.
>
> Have you taken any voltage, current and gain measurements and swept over a 
> wide range of frequencies?
>
> Id say that the choke is a bit on the small size, try something in the 5-7 
> uh range. Or better still feed the 12V thru a bifilar xfmr; 5-6 bifilar 
> turns on a FT23-43 would be about right..
>
> Also if you are trying for a clean output Id go 10 & 100 Ohms on the 
> emitter. The .01 is fine if its mono.
>
> What do you have available for test equipment?
>
> Carl
> KM1H
>
>
>
>
> ----- Original Message ----- 
> From: "R. Blackman" <richard.blackman at sympatico.ca>
> To: "HOMEBREW" <homebrew at mailman.qth.net>
> Sent: Sunday, November 28, 2004 10:56 AM
> Subject: [HomeBrew] 72 MHz amp
>
>
> ** Please do NOT cross-post messages in the TO: or CC: field of the e-mail 
> message. **
>
> Hi to the group.
>
> I am trying to build a low power amp for 72 MHz IF in a homebrew
> transceiver.
> The following circuit  works great  at 25 MHz but is dead at 72 MHz.
> Any advice would be appreciated.
>
>
>                  |--------------|-----2uH---------12vdc+
>                1000 ohm         |
>                  |              |
>                  |              |--------0.01uf --output
>                  |              |
>                  |  2N3866  b  /  c
> input---0.01uf----|------------[
>                  |             \--2.2 ohm----|-- 22 ohm---gnd
>                  |          e                |
>                  |                           |
>                 470 ohm                      |--0.01 uF---gnd
>                  |
>                  |
>                 gnd
>
> Thanks for any comments.
> Richard / VA3NDO
>
>
>
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