Dear Peter,
Thanks for answer.
Indeed, the SRS457 is equivalent to QB5/1750, but was made in the ex DDR
only,
and this is why it can't be found here.
I do not have any info about this tube to be built in the ex USSR.
I wanted to build amp with these tetrodes (I wanted to avoid the noisy
blowers,
so I don't want to use the existing GU74) and have not found any new or
NOS SRSs
or QBLs but only with very, very long time on them, or deffective ones.
Oppermann sold SRS 457 at about 80DM, someone gave me two of these, but
there
were signs of discharges inside them (of course, were not unused tubes
too).
It seems that the QBL5/1750 is hard to find these days...
Some Rohde & Schwartz transmitters are still working ok here, at full
power RTTY
in commercial instalations after about 30 years, using the original
tubes!
All the best,
Traian
DF3KV@aol.com wrote:
>
>
>
> yo9fzs asked:
>
> What russian tube is the QB5/1750 equivalent (or what russian tube did
>
>
>
>> you use instead of the QB5/1750)? It is the GU46?
>>
>
>
> Traian,
>
> The tube is the SRS457, it is exactly the same tube as the QB5/1750.
> It might be possible that it was first build in ex DDR.
>
> 73 de Peter, DF3KV
>
>
>>
>>
>
>
>
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