<div dir="ltr"><div class="gmail_quote"><div>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.<br></div><div><br></div><div>The same problem with SB-230 uses a 1KW tube that was no longer stock and depleted from the vendor's inventory.<br>Some Ham users use Russian-made microwave tubes to take over with some modifications.<br></div><div> </div><div>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.<br></div><div><br></div><div>Now, I am working on a new PCB for the SB-104A display to run with the LED instead of Panaplex.<br></div><div><br></div><div>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.<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div><br></div></div></blockquote><div>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.</div><div><br></div><div>Just try to keep Heathkit alive ahead of time!</div><div>Steven</div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div><br>
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<th valign="BASELINE" nowrap align="RIGHT">Subject:
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<td>Re: [Heath] Fwd: Final transistors for SB 104A</td>
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<th valign="BASELINE" nowrap align="RIGHT">Date: </th>
<td>Wed, 22 Sep 2021 12:56:01 -0700</td>
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<th valign="BASELINE" nowrap align="RIGHT">From: </th>
<td>Chris Iwata <a href="mailto:chrisiwata@aol.com" target="_blank"><chrisiwata@aol.com></a></td>
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<th valign="BASELINE" nowrap align="RIGHT">To: </th>
<td><a href="mailto:ka9dzr@aol.com" target="_blank">ka9dzr@aol.com</a></td>
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<br>
<br>
<p><br>
</p>
<p>If you luck out and find some, bear in mind that you have to
buy matched pairs.</p>
<p>Theoretically, you have to buy matched quads. But you can
probably be OK with matched pairs</p>
<p>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<br>
</p>
<p>Your best bet is to buy a junked SB104</p>
<p>The SB104 will become unrestorable due to unavailability of the
Final transistors, the Nixie tubes, the Nixie driver IC, and the
voltage regulator IC. <br>
</p>
<p>Chris, KL7DM</p>
<p><br>
</p>
<p><br>
</p>
<div>On 9/22/2021 10:18 AM, ka9dzr--- via
Heath wrote:<br>
</div>
<blockquote type="cite">
<div>
<div style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:rgb(0,0,0)">
<div><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:rgb(0,0,0)"> </span></div>
<div><span style="font-family:arial,helvetica,sans-serif;font-size:10pt;color:rgb(0,0,0)">has anyone fine any
replacement finals for the sb-104a yet tnx ka9dzr
Dennis</span></div>
<div> </div>
</div>
<div>
<blockquote style="padding-left:5px;margin-left:5px;border-left:2px solid blue">
<hr><span style="background-color:transparent;color:rgb(0,0,0);font-family:Arial;font-size:small"><span style="background-color:transparent;color:rgb(0,0,0);font-family:Arial;font-size:small">From: <a href="mailto:heath@puck.nether.net" target="_blank">heath@puck.nether.net</a><br>
To: <a href="mailto:heath@puck.nether.net" target="_blank">heath@puck.nether.net</a><br>
Sent: 11/24/2014 4:56:23 PM Central Standard Time<br>
Subject: [Heath] Final transistors for SB 104A<br>
<br>
</span></span>
<div dir="ltr">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.</div>
<div dir="ltr"> </div>
<div dir="ltr">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</div>
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