[baileyler]

MATCHED PAIR FIRST GENERATION GENALEX KT-88 VACUUM TUBES – MK4 (10/1956) AND NA4 (1/1957)

PLEASE READ THIS AD CAREFULLY AND IN ITS ENTIRETY! 

There are two scarce first generation KT-88 variations and, for that reason, I am asking [SOLD] for the pair.

Shipping and Paypal fee are extra (see below for terms and conditions).

Additional terms and conditions are provided below.  Trade may also be possible, but my needs are very limited (see below).

I have another early pair of second generation Genalex KT-88 (1958, top flashing) for sale in a different ad, and will discount for purchase of both pairs.

MK/NA DATE CODES

These two tubes appear to be scarce first generation production.  One has a date code of “MK4”, which I believe is October 1956.  The other has a date code “NA”, which I believe is January 1957.  My understanding is that the KT-88 was introduced in 1956, so these are from the FIRST YEAR OF PRODUCTION.

The “Genalex” sticker on tube #1 (MK4) is very clean, but worn on tube #2 (NA4).  There is a discoloration of the flashing on the top of both tubes.

EARLY KT88 TUBE SPECS

These early tubes are NOT what most people know as Genalex KT-88s.  These have a smaller bottle structure as compared to the later versions. 
A photo showing the size comparison is below (the other pair is for sale in a different listing).

From the data sheets I can find, the first generation KT-88 have slightly different specs than the later versions, for example, a maximum rated plate voltage of 600V (as opposed to 800V for later versions), and a maximum anode dissipation of only 35 watts (as opposed to 42 watts for later versions). 

I cannot say if these are even suitable for use in KT-88 amps designed around current production tubes.  I would check your amplifier specs to ensure that you are not pushing the design maximums of these tubes.

TEST RESULTS

I tested these tubes on an Amplitrex AT-1000 connected to a regulated power supply.  The tubes were tested in fixed bias mode.  The spec for “transconductance” (Gm) and “emission” (current draw) on the AT-1000 is 11.5 mA/V and 140.0 mA. 

The results are as follows:

Tube #1   9.3 mA/V and 114 mA
Tube #2   9.2 mA/V and 110 mA

I also did a life test on a B&K 707, and both tubes passed.

It would be difficult to find a set of these tubes that are any more closely matched than this pair (at least according to the Amplitrex).

I have never used these tubes, so I have no idea about sound.  As a general rule, I am not a good one to ask as most tubes sound about the same to my ears.  Either I like tube or I don’t, but I don’t always know why (and I can change on a daily basis).

I do not know the history of these tubes (I have owned them for a couple of years) so, for the purposes of this listing, these tubes should be considered USED.

I can provide additional information or pictures on request.

GENERAL TERMS AND CONDITIONS – PLEASE READ CAREFULLY

PLEASE NOTE THAT THESE TUBES ARE BEING SOLD “AS IS, WHERE IS”.   

ALL SALES ARE FINAL.

I ONLY describe what I know about the tube, and what I have tested for.  Although my tube testers tend to be reliable, YOUR TUBE TESTER MAY GIVE A DIFFERENT RESULT THAN MINE, so please take that into account. In the event of a tube tester conflict, MY TUBE TESTER CONTROLS.

If the information is not there, DO NOT ASSUME, and do not rely on any of YOUR assumptions. If you need more information than provided in the listing, ASK IN ADVANCE. If I happen to have the information, I will provide it. If I can get the information in a reasonable way, I will get it. If I do not call a tube NOS, consider that tube USED. I do the best I can with very limited time and capabilities. I am an honest seller, but I am NOT a tube professional, and I am NOT in the tube business.

AS SUCH, PLEASE NOTE THAT I CANNOT GUARANTEE (OR EVEN REMOTELY PREDICT) HOW THESE TUBES WILL SOUND OR PERFORM IN YOUR EQUIPMENT. THE TEST RESULTS ARE ONLY PROVIDED AS AN INDICATION OF TUBE PERFORMANCE IN A VERY LIMITED (AND NON-IDEAL) ENVIRONMENT. EXCEPT AS EXPRESSLY INDICATED IN THIS LISTING, I DISCLAIM ANY AND ALL REPRESENTATIONS, WARRANTIES AND LIABILITY WITH RESPECT TO THESE TUBES, OR RESPONSIBILITY FOR YOUR USE OF THEM.

The buyer is responsible for all shipping charges (including but not limited to any customs fees, duties, import taxes and related charges).

Shipping will be via USPS Priority Mail (domestic and international) unless an upgraded service is requested. 

I WILL NOT FALSIFY INFORMATION ON A CUSTOMS FORM.

For all shipping, the terms are EXW US Post Office (INCOTERMS 2010).  In accordance with these terms, I will deliver the lot into the possession of the US Post Office, and once in the possession of the US Post Office ALL RISK OF LOSS PASSES TO THE BUYER.

WHAT THIS MEANS IS THAT I EXPRESSLY DISCLAIM ANY AND ALL RESPONSIBILITY FOR DELIVERY (INCLUDING BUT NOT LIMITED TO DAMAGE OR LOSS) BY ANY POSTAL SYSTEM, AND BY PURCHASING THIS LOT YOU EXPRESSLY WAIVE THE RIGHT TO FILE A CLAIM (INCLUDING BUT NOT LIMITED TO BUYER PROTECTION CLAIMS WITH EBAY AND PAYPAL) FOR ANY SHIPPING RELATED ISSUE.

If, however, you have purchased insurance for the item, I will assist to the best of my ability in the processing of any legitimate insurance claim you desire to file.

Cash is always welcome for a local transaction. Payment can also be via money order/cashier’s check/personal check preferred but, except for US Postal Money Orders, all must clear my bank first.

I also accept Paypal for convenience, but add 3% to use Paypal in the USA or 4% outside the USA. IF YOU PAY VIA PAYPAL, HOWEVER, A CONDITION OF YOUR PAYMENT IS THAT YOU EXPRESSLY WAIVE THE RIGHT TO FILE A PAYPAL CLAIM OR CHARGE BACK (but do retain the right to sue me in court should you so desire).

Trade is also possible, but my needs are very limited and it would need to be a pretty good deal.  I might be interested in certain vacuum tubes (KT90, vintage 805, interesting 6CG7, vintage 5AR4/GZ34, or possibly others) and other things at the right value).  If need be, I have other tubes and equipment that I can bring into any trade talks. 

In any event, it does not hurt to ask.

Please check my feedback on Ebay (ID=baileyler), and buy with confidence.