The first challenge is to figure out the transistor they used , HP had their own foundry and not all parts they made were sold as products on the open market.
Given the frequency range of the yig it was likely to be a HBT rather than a GaAs Fet but HP semiconductor became Avago and then broadcom and to my knowledge they don¡¯t sell die level parts!
The next challenge then is to remove the old transistor and mount a new one, usually devices are mounted using eutectic solder preforms , the stage is heated until the solder melts and the part is then ¡°scrubbed ¡° in as gold from the back metalization
diffuses into the solder the melting point increases and the solder solidifies , in order to remove the part you would have to heat up the solder past the new melting point without imposing thermal stress on the other parts used or dislocating them !
To mount a new part you need a die attach as well as preforms, you could of course use conductive epoxy but the heat transfer generally is not as good as with eutectic die attach so you might run into issues with reliability!
As far as wirebonders concerns there are plenty on ebay , expect to pay between $5000 and $16000 for a refurbished one , for this type of work you need a wedge/wire bonder , if you plan on rebuilding modules plan on getting a deep access bonder or a convertible
machine that can be used for different processes .
The biggest challenge with bonding is to figure out the right settings though, usually in a production environment the supplier of the semiconductor devices used provides bond samples which in essence are parts that are not working ok those samples are
then bonded in a dummy circuit and a pull tester is used to check the strength of the bond?
Also make sure you have someone with a steady hand and young eyes to threat the bonder ? and also invest in a vibration isolation table or platform to set your bonder on?
toggle quoted message
Show quoted text
On Mar 22, 2022, at 02:28, Peter Hansen via groups.io <oz1lpr@...> wrote:
?
I have succeded to integrate a YO84 YIG faily simple and you can use +/-15 for 30V for heater it is ok and shunting the Sense resistors in the Maincoil driver means it can span the 3-7Ghz. I have made changes to the Loop so it is yield low Phase noise. Output
from the YIG it self is good also. Mechanical implementation is done by using the original mechanic shell and make a hole for the YIG. It can be jammed in there when I mount the YIG in the unit. A PCB "still prototype" is mounted with a 10pin pinheader so
the orignal cable can be used. BUT BUT now the challenge. The original YIG does not get hot due to the sensitve coils meaning less drift. If the Loop is opened by placing the jumper in the TEST position I observe a drift of the YIG of around 5Mhz from cold
to warm. The Avantek YIG drift around 30-40Mhz. The Loop is build to compensate for 10Mhz drift. This means you can either have a unlock condition ERR301 during warm up or you will get it during use.
Playing around in the Loop is not a things for the average guy to do. The Frequency Lock? circuit is quite hard to work with. Changes to the loop will also challenge your phasenoise performance. I am sure this is why HP deviated from the standard sensitivity
on the maincoil to keep drift down. The avantek YIG gets hot the HP ones do not.
More fruitfull would be to find a replacement for the Bonded Transistor and get someone with a Wirebonder to service them.
I do currently not have a wirebonder but as I am repairing alot of advanced HP equipment I am considering it. But where to source components for tryouts.
best regards Peter OZ1LPR
Hi Peter, Et al,
Sorry for the delayed response to all the positive comments. I have been away camping, soaking up what is left of the good weather in autumn, trying my new HF radio set up.
No doubt, there will be many challenges ahead, but I am determined to find a solution. I am waiting on a mail from Micro Lambda to see if they have ever made a replacement, the chap is going to ask the question for me, they have been so helpful to date. There
are other Micro Lambda models to suit Tek and R&S, so they have made replacement models for branded SA and Sign Gens. No harm asking.?
Peter, I think the original HP data sheet is right, this does represent a challenge at? or around 40MHz/mA, the hardware and software is tightly integrated, thus a YIG with similar spec or the development of an interface driver is needed. I haven't thought
that far ahead yet.
Like yourself, and I am sure others on the forum have purchased a YIG in the past to adapt, I purchased a Avantek Y084-1215 about 10 years ago, I recently tried to adapt via a crude interface driver, but this did not work out to well. Although the Avantek YIG
works extremely well for it's vintage, it's main coil spec is way out at ~22.4 MHZ/mA. In addition, getting the juice to run the heater from an internal supply is a challenge.
I am prepared to lay out the cash up to a point to develop a solution.
I hope I do not have to eat my words in time.
Stay tuned.
Regards
Gerald
VK3GM
?
