Topband: Anyone have a boat load of J-310s?

[Charlie Cunningham]

Gee, that's really interesting, Andy!  I also built a much simpler
oscilloscope when I was a teenager and new ham! Yours was a really elaborate
and impressive 'scope project! Congrats!

Glad to hear from someone who has experience with the KAZ and flag antennas.
My KAZ was for 160 and terminated in 1000 ohms - mostly because that's what
I had on hand. It was a very good RX antenna for 80, 40 and 30m as well.

Your preamp sounds very interesting!  It must be fairly elaborate, if it
uses 8 of the J309 FETS! I'd be interested in the circuit!

Best regards,
Charlie, K4OTV

-----Original Message-----
From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Andy Ikin
Sent: Sunday, August 25, 2013 6:32 PM
To: Charlie Cunningham
Cc: Topband Reflector
Subject: Re: Topband: Anyone have a boat load of J-310s?

Charlie,

When I was poor man 40 years ago, I always wanted  Tektronix 545B Scope, 
which I couldn't afford. So I built a "Chinese Copy" with discarded parts 
from the Calibration department of the computer company I worked for. The 
scope use many 6DJ8s. I did get it working after about a year; not bad for 
some one with no formal electronics training!!!! Tektronix were very helpful

in supplying some critical parts. Looking back I must have been mad, but it 
was one hell of away to learn how these things work.!!!!

Bye the way I manufacture a special Head Amplifier for the KAZ and other 
Flags. This has 1100 Ohm input matching/isolation transformer, about 20dB 
gain and a less than 1dB NF and uses 8 x J309s plus a string of 1N4148 
limiting diodes. Wellbrook FLG100LN. There are about 70 units in service 
mainly in the US with MW Dxers.


73

Andrew G8LUG

----- Original Message ----- 
From: "Charlie Cunningham" <charlie-cunningham at nc.rr.com>
To: "'Andy Ikin'" <andrew.ikin at btopenworld.com>
Cc: "'Topband Reflector'" <topband at contesting.com>
Sent: Sunday, August 25, 2013 10:29 PM
Subject: Re: Topband: Anyone have a boat load of J-310s?


> Yes, we could swing the grids of those tubes quite a ways before
> encountering enough non-linearity to produce a significant amount of
> intermod, Andy!  The old original AMECO tunable vacuum -tube preamp, that 
> I
> borrowed from Bill, K4CIA, worked really well with my KAZ terminated RX 
> loop
> for the low bands. It was  connected to the receive antenna port on my
> FT-1000MP, so I wasn't blowing FETs!
>
> My electronic design career began before the end of the vacuum-tube era, 
> and
> I used the 6DJ8 commercially in some VHF monitor receivers, as a cascode 
> RF
> stage in the front-end.
>
> 73,
> Charlie, K4OTV
>
>
> -----Original Message-----
> From: Andy Ikin [mailto:andrew.ikin at btopenworld.com]
> Sent: Sunday, August 25, 2013 5:16 PM
> To: Charlie Cunningham
> Cc: Topband Reflector
> Subject: Re: Topband: Anyone have a boat load of J-310s?
>
> Thirty years ago I used 6DJ8 (E88CC) to solve a third order IMD problem 
> with
> tuned loop that was using J310s.
>
> The IMD was caused by Radio Free Europe on 13m.
>
> 73
>
> Andrew
> ----- Original Message -----
> From: "Charlie Cunningham" <charlie-cunningham at nc.rr.com>
> To: "'Andy Ikin'" <andrew.ikin at btopenworld.com>; "'Topband Reflector'"
> <topband at contesting.com>
> Sent: Sunday, August 25, 2013 9:14 PM
> Subject: Re: Topband: Anyone have a boat load of J-310s?
>
>
>> Of course,  a 12AT7, or better, a 6DJ8, would be excellent preamps as
>> well,
>> and aren't so sensitive to transients etc.  :-)  (Showing my age, I
>> guess!)
>>
>> -----Original Message-----
>> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Andy
>> Ikin
>> Sent: Sunday, August 25, 2013 3:58 PM
>> To: Topband Reflector
>> Subject: Re: Topband: Anyone have a boat load of J-310s?
>>
>> As far as am aware On-Semi still make the TO-92  J310. Fairchild ceased
>> production about 2 years back. I did a last time buy from Mouser for
>> several
>>
>> thousand J310 and the much more linear J309.
>>
>> 73
>>
>> Andrew Ikin G8LUG
>>
>>
>> _________________
>> Topband Reflector
>>
>> _________________
>> Topband Reflector
>>
>
>
> _________________
> Topband Reflector
> 


_________________
Topband Reflector