Re: whistles in receive

Jack, W8TEE
 

One can get carried away, however...

Inline image
Jack, W8TEE


From: Leland Lannoye <wa9aoe@...>
To: BITX20@groups.io
Sent: Monday, February 5, 2018 10:49 AM
Subject: Re: [BITX20] whistles in receive

There have been numerous articles in QST over the years on rebuilding these old rigs.  I found an article which I saved somewhere on building transistor substitutes for the tubes.  you could build them on small perf boards and set up a set of wires that corresponded to the pin out on the tubes.  At one time, someone was making modules to replace all the low power and receiving tubes on the Collins S line.  That was at least 40 years ago.  I don't do well on a lot of these tiny connections anymore due to age and aging eyes, but my history skills are still largely intact.
Lee, WA9AOE
PS: Still awaiting shipment on my Bitx.
On 2/5/2018 10:40 AM, Ashhar Farhan wrote:
The warm smells of an HRO steaming up... is there any hotroding one can do to these rigs?
- f

On 5 Feb 2018 12:02 am, "Leland Lannoye" <wa9aoe@...> wrote:
I am sitting here reading some of this information and studying the new technology.  When I was young (at leas 50 years ago), solid state technologies were either in their infancy or still a dream.  Our rigs were two pieces of equipment, a receiver and a transmitter with a variety of accessories.

Most of our receivers for those of us who were not well heeld in the financial area were of the single conversion genre with an if frequency of 455 kHz.  With little preselection capability, this relegated the ham bands 20 mtrs and above useless with hetrodyne images from frequencies 910 kHz either above or below the desired reception point. There, in that day, were three remedies to fix this. The first two were:

    1.)  add a really selective high gain preselector to tune the offending images out

    2.)  raise the if to something on the order of 1600 kHz which left bandpass selectivity at a substantial disadvantage.

The third option, and the most expensive in its day was double (or, even triple) conversion.  If  you were able to pay the 1958 price of over $300, you were in and there were few difficulties thereafter until the receiver aged and developed some bad shield grounds or worse.  The second or third conversion local oscillator would provide a cornu copia of birdies of one type or another. These included signals that were always there, I know the newer designs with balanced mixers and the like have few of these problems, but, it is worth considering.

An aging ham from way back.


Lee, WA9AOE


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