[R-390] R-390A Antenna matching, 26Z5W, 3TF7, 0A2 replacements available? Recommendations?

[Larry H]

Hi Scott,  You can contact them directly at: sigmapert 'at' gmx 'dot' de and
I believe they still produce some of those items.

However, unless your 120 vac power fluctuates, a 3tf7 is not necessary.  I
suggest using a 12bh7 or 12by7, instead.  There's been discussions about
this you can look up (search the archives with the HHI email reflector
search tool).

And, as for the antenna balun, if you are not experiencing common mode
interference, the balun signal loss is something to consider on weak signal
reception.  The 125 ohm balanced antenna connection on these receivers is
designed to work with impedances of 50 to 200 ohms without much of a
mismatch. The loss is extremely small, so using a balun to overcome the
imbalance would introduce more loss than without a balun.  The least
insertion loss available today in this type of balun would be about .5 db
on the low frequency side, and up to 2.5 db on the high side.  The maximum
loss without a balun due to a mismatch on an R390A is about .3 db.
 Impedance matching in this range on a receiver is not very important.

Regards, Larry

On Sun, Aug 11, 2019 at 11:21 AM James Anderson <ScottA0227 at outlook.com>
wrote:

> Do you know if Sigmaperts replacement as follows are still available?
>
>
>   1.  BNC 50 ohm unbalanced to Twinax 125 ohm balanced antenna adapter for
> the R-390A
>   2.  26Z5W replacement
>   3.  3TF7 replacement
>   4.  0A2 replacement
>
> I am looking to update my R-390A and from a couple of recommendation you
> made of them I would like to buy them.
> If not available do you have suggestions for substitutes?
>
> Thanks for your help,
>
> J. Scott Anderson
> 503-789-3438
>
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