Re: Questions from a newbie...

Ashhar Farhan <farhan@...>
 

roy,

w7zoi recently wrote a very nice letter to me about our two groups (the H&P and bitx20). he has been an inspiration to me through his writings as well as in a personal capacity.

the feedback values dont have to be changed at all. almost any HF transistor will work just as well.

crystals should not be a very difficult challenge. you can check out the commonly available crystals for computers. from your posting, i gather that you are contemplating a 21MHz transceiver. Crystals of 8MHz, 12Mhz are common. you can try for them at tthe computer spares stores.

it is vital that the crystals have to be matched within 50-100Hz. otherwise, you will have greater losses and ringing. but what the heck! go ahead and make the filter. we will all learn from it. at worst, one of us will mail the crystals to you.

- farhan

On Wed, 19 Oct 2005, Roy E. Ruivivar wrote:

Hello to All,

First, I would like to say that I am so honored to be accepted to
this Group of truly famous and techically elite Amateurs such as
W7ZOI, Mr. Hans Summers, Farhan, Arv, Prof. Rob, Rahul, just to name
a few.

I am a new member of this Group from the Phillipines. After a week of
reading through the Message Archives, I learned more from this group
than all of the years of browsing through the Internet.

I am still preparing to start on my version of the BITX15 and would
be using some of the information already posted in the past. I have a
few questions:

1. I plan to use either the 2SC2570 (fT=5 Ghz) or 2SC2347 (fT=800
Mhz). The 2N's and BC's are difficult to find here. Do I have to re-
compute the values of the Feedback/Bias resistors of the Bi-
directional Amps?

2.Crytals are very expensive in the Philippines. I have accumulated a
number of 10.240 Mhz Crytals from old equipment I salvaged but I only
have 3 that are 700 Hz from each other. I also have Three 16 Mhz
Crytals also 800 Hz from each other. CAn 2 or 3 pole Ladder Filter
suffice. How about Ceramic Filters? These 10.7 Mhz CF's are really
cheap here. They can be "pulled" easily.

Sorry for the long message.

Thank you very much.

ROY









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