[ARC5] Why "Noodling" About Sweep Tubes

[Dennis Monticelli]

Jim,

Thanks for the details.  So you didn't have to recess the tube socket or
use an electrostatic shield to partition the input/output pins under the
chassis?

Dennis AE6C


On Wed, Oct 23, 2013 at 10:13 PM, Jim Wiley <jwiley at gci.net> wrote:

>  Just the usual things.  Parasitic suppressors on the plates (a 47-ohm
> 2-watt carbon resistor wrapped with about 7 turns of #20 wire), a 100-ohm
> 1-watt series resistor for each control grid, good grounding of the
> screens, good isolation between the grid and plate circuits, good bypassing
> of the plate and screen HV feeds, and of course careful neutralization. I
> seem to remember that it was a push-pull final, but I could be wrong about
> that part - it was, after all, 50 years ago.  The VHF version (6 and 2
> meters) was definitely PP. I think I also remember running the screens at
> somewhat reduced voltage for HF service.  I was working for RCA at a
> mountain-top site in Western Alaska, and we had lots of spare parts.  We
> had dozens of 5763s and 5894s, but no 6AG7s, 807s or 6146s.  Need I say
> more?
>
> - Jim, KL7CC
>
>
>
>
>
> On 10/23/2013 8:43 PM, Dennis Monticelli wrote:
>
> Jim,
>
>  Thanks for the info on the 5894.  I have one of those but have been
> reticent to use it fearing that the high gain at VHF might make it tough to
> tame at HF.  Did you take any special precautions when you built that
> multi-band HF rig?
>
>  Dennis AE6C
>
>
> On Wed, Oct 23, 2013 at 7:55 PM, Jim Wiley <jwiley at gci.net> wrote:
>
>> The much better version of the venerable 829A, that fits the same socket
>> and runs from the same voltages, is the 5894A (also known as the QQV06-40A
>> and AX9003A).
>>
>> Also inexpensive, because not many people know what they are,
>> particularly when labeled using the European numbering system. Puts out
>> more power than the 829B, mostly because it was designed from the ground up
>> as a VHF dual power tetrode,  so it is a bit more efficient.
>>
>>  I built a HF rig using one and got around 150 watts output, 160 thru 10
>> meters.  Used another in a Johnson-Viking 6N2 and got an easy 110 watts AM,
>> 140 watts CW output. The 5894A works at full power up thru 180 MHz and at
>> reduced ratings thru 450 MHz.
>>
>>
>> - Jim, KL7CC
>>
>>
>>
>> On 10/23/2013 6:21 PM, Kenneth G. Gordon wrote:
>>
>>> On 23 Oct 2013 at 18:36, Dennis Monticelli wrote:
>>>
>>>> I just remembered another tube. The 829B was very expensive in the WW2
>>>> era but it's practically free at the hamfests now. You find them mil grade
>>>> NIB. I don't think I paid more than $2 for mine. You can parallel the two
>>>> tetrode sections or use them push-pull. I think they're good for 40W plate
>>>> per section. 12V heaters and a 7 pin socket (Septar?) that is worth more
>>>> than the tube.
>>>>
>>> The 829B is one of my favorite tubes. The pulse version is the 3E29. I
>>> buy them as often as I see them for under $5 each. They will output
>>> something like 100 watts at 2 meters. They are, essentially, a pair of 807s
>>> in one envelope with far shorter interconnecting leads, and reduced plate
>>> dissipation rating since you can't really have 70 watts PD in that small an
>>> envelope. They make a magnificent push-pull oscillator in addition to being
>>> an excellent push-pull amp. Ken W7EKB
>>>
>>
>>
>
>