[Heath] Fwd: Fwd: Final transistors for SB 104A

[Steven Feinsmith]

First of all, both SB-104, SB-104A, and SB-230 are not dying. The 2N6456 RF
transistors have indeed become more difficult to find nowadays. The greedy
eBay sellers pumped for around 100 dollars each. Of course, no one is
buying 400 dollars. There is a big issue about whether a matched quads may
be impossible. I did mention in my previous message that I should buy an
old rig that uses the 2N6456.

The same problem with SB-230 uses a 1KW tube that was no longer stock and
depleted from the vendor's inventory.
Some Ham users use Russian-made microwave tubes to take over with some
modifications.

The front panels use a Panaplex display. It is a gas discharge display that
was very popular and easy to read. There was a slight problem with the
Panaplex because it requires 180 volts to run the gas discharge. It tended
to give out some electrical noise. There are articles about converting
Panaplex to LED  for both SB-634, station, and SB-104A, transceiver.

Now, I am working on a new PCB for the SB-104A display to run with the LED
instead of Panaplex.

The problem is with the new ham radio transceivers that physically shrink a
lot, but it had many features, such as digital modes with USB ports. The
amplifier tends to use high-power transmitting tubes now as MOSFET. The
price tag, OUCH! I am poor as a retiree and earn a social security
retirement check every month.

>
> You mentioned voltage regulators. My SB-104A is running fine as a licensed
operation tested them. I checked everything with my DMM/VTVM to ensure
voltages are within specification. Can you explain the details about the
voltage regulators. I also found my HP-1144 power supply seems to have two
filter capacitors that may need replacement. The cost is crazy as I bought
a switching power supply that provides matched voltage and provides 30A
instead of 20A with overvoltage and overcurrent protection. The advantage
with the switching power supply was that it was very light compared with a
massive transformer's weight.

Just try to keep Heathkit alive ahead of time!
Steven

>
> -------- Forwarded Message --------
> Subject: Re: [Heath] Fwd: Final transistors for SB 104A
> Date: Wed, 22 Sep 2021 12:56:01 -0700
> From: Chris Iwata <chrisiwata at aol.com> <chrisiwata at aol.com>
> To: ka9dzr at aol.com
>
>
> If you luck out and find some,  bear in mind that you have to buy matched
> pairs.
>
> Theoretically, you have to buy matched quads.  But you can probably be OK
> with matched pairs
>
> Expect to pay a premium, those  stud mount RF transistors haven't been
> made for at least 20 years. A guess would be at least $50 each
>
> Your best bet is to buy a junked SB104
>
> The SB104 will become unrestorable due to unavailability of the Final
> transistors, the Nixie tubes, the Nixie driver IC, and the voltage
> regulator IC.
>
> Chris, KL7DM
>
>
>
> On 9/22/2021 10:18 AM, ka9dzr--- via Heath wrote:
>
>
> has anyone fine any replacement finals for the sb-104a yet  tnx ka9dzr
> Dennis
>
>
> ------------------------------
> From: heath at puck.nether.net
> To: heath at puck.nether.net
> Sent: 11/24/2014 4:56:23 PM Central Standard Time
> Subject: [Heath] Final transistors for SB 104A
>
> I have learned that the 2n6456 final RF transistors are no longer
> available and I NEED to replace the four (4) in a Heath SB 104A. Has anyone
> found a suitable replacement transistor for this application? I have
> thoroughly checked with RF Parts and they no longer stock those transistors.
>
> Does anyone have experience substituting the final transistors in the SB
> 104A? If so what did you use as a replacement  and do you know where they
> can be found? Thanks and 73, John, K5PGW
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