6al5's Anyone?

[Edward B Richards]

More from Bigmouth;
I doubt a TV balun would have enough inductance to work well at the lower
HF frequencies, but if you want to try it I have several and will send
you one gratis if you send me your address. I would try making one on a
small ferrite core. I am not engineer enough to design it from scratch,
but I know some who might. Let me know if I can be of help. Regards.
Ed Richards


On Thu, 07 Jan 1999 07:55:31 PST "John Campbell" <r3campbell at hotmail.com>
writes:
>hello....
>
>    On the Collins question...I'm not a Collins man, but I presume
>that
>the 300 Ohm input is probably balanced. Why don't you try running down
>
>to Radio Shack and getting a 300/75 Ohm TV balun and trying it on the
>Collins. They are only about 3 to 5 bux. I don't know what the low
>frequency cutoff of these baluns is, but for the price it would be
>worth
>a try. Certainly easier than redesigning the receiver front end.
>Just a thought..........73...John (W8JNC)
>
>
>
>>Date:         Thu, 7 Jan 1999 06:23:42 -0800
>>Reply-To:     Edward B Richards <k6uuz at JUNO.COM>
>>From:         Edward B Richards <k6uuz at JUNO.COM>
>>Subject:      Re: 6al5's Anyone?
>>To:           HEATH at LISTSERV.TEMPE.GOV
>>
>>Dave;
>>Some thoughts:
>>1. In my 50 years of repairing radios I don't think I have found 3
>bad
>>6AL5 tubes. They are a dual diode and very long life. I suggest you
>pass
>>this one by and should you ever need one you can get it for less than
>
>the
>>$10 you mention,
>>2, On the Collins antenna impedance, if you use a 4:1 balun you will
>have
>>a 75 ohm input which, using 75 ohm coax, is a perfect match for a
>dipole
>>antenna (theoretically, in free space).
>>Regards and Happy Y2K-1.  Ed Richards
>>
>>
>>On Thu, 7 Jan 1999 07:26:26 -0600 "James D. Mayfield"
>><kb9bnr at REVEALED.NET> writes:
>>>I am not trying to get in to the tube business. I had a call
>yesterday
>>>from
>>>a guy I know and he offered me some 6al5's NOS mil spec tubes. I
>have
>>>to
>>>buy them in lots of 100. I would not mind having ten for myself but
>I
>>>don't
>>>need 100. If I could find 7 or 8 of you guys that would commit to
>>>buying 10
>>>each for $10.00 shipped to you, I will get these for us. Do I have
>any
>>>takers? I will buy more if the demand is there.
>>>
>>>By the way I got my first Collins, this week. It's a 75A1, and it's
>in
>>>very
>>>nice shape. The alignment was a bit out of wack, but a few minutes
>on
>>>the
>>>bench and it was working just fine.
>>>
>>>Also here is a good question for you Collins guys. The gent I bought
>>>it
>>>from told me that since it was designed for use with a 300 ohm
>>>antenna, it
>>>would be a little deaf it feed with 50 ohm coax. That is certainly
>the
>>>case. I found that if I feed the input signal directly to pin one of
>>>v1
>>>(6ak5) then the radio really comes to life! but this seems wrong to
>>>me. I
>>>was told and I agree that it should be feed thru a cap to pin one,
>but
>>>I
>>>have no idea what value. Looking at the handbook last night, I saw
>>>several
>>>circuits that used a 100 or up to 250 pf cap to the input. What do
>you
>>>think.....
>>>
>>>73 Dave
>>>
>>>*********************************************
>>>Dave Mayfield KB9BNR
>>>Personal Web Page
>>>http://home.revealed.net/qste/bnr/kb9bnr.html
>>>
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>
>
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